Role of Secondary Metabolites to Attenuate Stress Damages in Plants

*Masuma Zahan Akhi, Md. Manjurul Haque and Md. Sanaullah Biswas*

## **Abstract**

Plants are constantly facing various threats posed by the biotic and abiotic stressors. To survive in these challenged environment, plants evolve a variety of defense mechanism. Among the various phytochemicals, secondary metabolites (SMs) accumulate higher amount under stressful conditions and initiate signaling functions to up-regulation of defense responsive genes. SMs ensures the survival, persistence and competitiveness of the plant against the threat generated under stressful conditions. Therefore, the signaling functions of SMs to protect the plant from biotic and abiotic stressors are getting importance in the recent times. In this chapter the contribution of SMs to protect the plant from specific environmental stresses has been discussed.

**Keywords:** reactive oxygen species, environmental stress, biotic and abiotic stress, plant tolerance and adaptation, programmed cell death

### **1. Introduction**

A hundred years ago it is reported that primary metabolites (carbohydrates, proteins, amino acids, vitamins, acetone, ethanol, etc.), are involved in various life functions in plants such as cell division, growth and development, photosynthesis, respiration, and reproduction [1]. However, Kossel was the first to define the secondary metabolites (SMs) as opposed to the primary ones and then concept of SMs has been introduced in plant biology [2]. The term metabolite is usually confined to tiny molecules and products of metabolism. Plants produce unlimited and manifold assortment of organic compounds, the great majority of which do not take part in growth and development immediately. These substances commonly referred to as SMs, often are differentially distributed among limited taxonomic groups within the plant kingdom [3]. In the last decade SMs, low molecular compounds occurring in all living organisms while mostly distributed in plants, became a subject of dramatically increasing interest relevant to their outstanding practical implication for medicinal, nutritive and cosmetic purposes, as well as to their undebatable importance in plant stress physiology [4].

Recent advances of SMs research on plant stress physiology suggesting its involvement to the mitigating detrimental effects of various stressors [5, 6]. In addition to the protective functions of SMs, they also act as defending molecules of primary metabolites such as proteins and nucleic acids from stress-induced damages [7, 8]. Therefore, physiological modifications such as secondary metabolism

adjustment, ion and water balance, minimization of oxidative damage etc. occurred in plant body which can provide the phenotypic response of stress tolerance directly or indirectly. The stress response could also be a growth inhibition or cell death [9–11], which will depend upon how many and which kind of genes are up- or down-regulated [12]. However, most of the cases secondary metabolism adjustment play an important role in defense mechanism either increasing or decreasing their production in plant body. In this chapter the role and involvement of SMs in regulation of various biotic and abiotic stresses in plants has been discussed.

## **2. Plant responses to stress factors**

Plants throughout their life cycle are subjected to various forms of biotic and abiotic stresses, as a sessile organism plants lack the ability to escape from that danger areas. Plants express responses to stress conditions in three ways. Some plants avoid the stress altogether (e.g. ephemeral, short-lived, desert plants), some show susceptibility to stress which may ultimately lead to plant death and some show resistant capacity [13]. To defend themselves against diverse stresses, plants have evolved complicated and highly regulated systems. To cope with these challenging environment plants evolve some efficient mechanism such as adjustment in photosynthetic rates, stomatal conductance, transpiration, cell wall architecture, remodeling of membrane structure, alterations in cell cycle and division rates with overall effect on general growth to fine-tune physiology and metabolism of bioactive compounds [14]. Initiation of stress and defense responses are mediated by signaling processes and pathways which trigger the primary metabolism that provides biosynthetic intermediates for secondary metabolism in plant body. These include the stress responsive system and the inducible defense system which depends on inducible activation of massive defense-related genes, suit of molecular and cellular process as well as inducible production of diverse defense-related SMs [15]. Plant accumulate a large number of SMs from primary metabolites in cells, and the production of that metabolites are regarded as an adaptive capacity in coping with stressful constraints during challenging environment [16–18].

## **3. Mechanism of stress adaptation in plant**

Generally, a stress signal transduction pathway comprises the following key steps: (i) signal perception; (ii) signal transduction; and (iii) stress response. The first step in the activation of signaling cascade for any given stress is the recognition of stress signals via receptors located on the membrane of plant cell. Recently a few research works indicated that various plasma membrane proteins like COLD1 (Chilling Tolerance Divergence-1) [19], CNGCs (cyclic nucleotide nucleotidegated channel), GLR (glutamate-receptor like) channel, histidine kinases, calcium channel are the main sensors for stress signaling. After recognition, the receptors transmit the signal into downstream through phytohormones and second messengers such as Ca2+ and ROS [20]. The second messengers, like ROS, trigger the activation of another set of ROS-modulated protein kinases (PKs) and protein phosphatases (PPs), including MAPK (mitogen-activated protein kinase) cascades, CDPKs (calcium-dependent protein kinases), CBLs (calcineurin-B-like proteins), CIPK (CBL-interacting protein kinase), and many other PKs as well as PPs such as some PP2Cs (protein phosphatase 2Cs). Subsequently, these PKs and PPs deliver the information downstream and trigger a series of phosphorylation or dephosphorylation of transcription factors (TFs), that finally culminates either directly in the

**549**

under stress stimuli.

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants*

expression of functional genes involved in cellular protection, or indirectly in the expression of regulatory genes participating in signaling cascades and transcrip-

peroxidase) and non-enzymatic antioxidants (such as ascorbic acid, reduced glutathione, α-tocopherol, carotenoids, flavonoids), primary metabolites including sugars, amino acids contribute to cellular homeostasis to adapt under stressful conditions [21]. Recently, the research advances supporting that products of secondary metabolism are important to alleviate toxic effects of stresses [5] through expression of stress responsive genes. Therefore, in presence of stress signals accumulated various species of SMs are critically important for adaptation

**4. Generation and diversity of secondary metabolites in plants**

In addition of the enzymatic (such as superoxide dismutase, catalase, ascorbate

Plant SMs are classified into four major categories. These four categories include (i) terpenes (such as carotenoids, sterols, cardiac glycosides and plant volatiles), (ii) phenolics (such as lignans, phenolic acid, tannins, coumarins, lignins, stilbenes and flavonoids), (iii) nitrogen containing compounds (such as cyanogenic glycosides, alkaloids, and glucosinolates) and (iv) sulfur containing compounds (such as glutathione, phytoalexins, thionins, defensins and lectins) [22, 23]. But on the basis of biosynthesis pathways plant SMs are usually classified into three chemically distinct groups [24]. The diverse chemical structures of the SMs determine their functions to the medicine and stress adaptation. Three major categories are (i) terpenes derived from mevalonic acid pathway [25] and methyl erythritol phosphate pathway [26], (ii) phenolics derived from malonic acid pathway or a few case shikimic acid pathway [27], (iii) N (Nitrogen) and S (Sulfur) containing compounds via tricarboxylic acid cycle or sometimes via shikimic acid pathway. Among the pathways of SMs accumulation, shikimic acid, mevalonic acid, phenylpropanoic acid and methyl erythritol phosphate pathways are highly regulated

Plants produce various types of SMs, many of which have been subsequently exploited by humans for their beneficial roles in a diverse array of biological functions [28]. Terpenes are one of the diverse species of SMs contribute to the various biological process in plants. Terpenoids are terpenes with an oxygen moiety and additional structural rearrangements. Therefore, these two terms of terpenes and terpenoids are used interchangeably. Terpenoids have their roles in plant defense against biotic and abiotic stresses or they are treated as signal molecules to attract the insects for pollination. The first step of terpenoid biosynthesis is generation of C5 unit like as isopentenyl diphosphate (IPP) or dimethylallyl diphosphate (DMAPP). On the basis of C5 units, we can classify the terpenoids as C5 (hemiterpenes), C10 (monoterpenes), C15 (sesquiterpenes), C20 (diterpenes), C25 (sesterpenes), C30 (triterpenes), C40 (tetraterpenes), C40 (polyterpenes) [29–31].

The rate of terpene emission in *Pinus sylvestris subsp. nevadensis* is increased due to attack of the caterpillar of Pine Processionary Moth (PPM). PPM is the main

*DOI: http://dx.doi.org/10.5772/intechopen.95495*

tional regulation of gene expression.

and tolerance to the altering environment.

**5. Terpenes for stress responses in plant**

**5.1 Terpenes for biotic stress responses**

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants DOI: http://dx.doi.org/10.5772/intechopen.95495*

*Antioxidants - Benefits, Sources, Mechanisms of Action*

**2. Plant responses to stress factors**

during challenging environment [16–18].

**3. Mechanism of stress adaptation in plant**

adjustment, ion and water balance, minimization of oxidative damage etc. occurred in plant body which can provide the phenotypic response of stress tolerance directly or indirectly. The stress response could also be a growth inhibition or cell death [9–11], which will depend upon how many and which kind of genes are up- or down-regulated [12]. However, most of the cases secondary metabolism adjustment play an important role in defense mechanism either increasing or decreasing their production in plant body. In this chapter the role and involvement of SMs in regula-

Plants throughout their life cycle are subjected to various forms of biotic and abiotic stresses, as a sessile organism plants lack the ability to escape from that danger areas. Plants express responses to stress conditions in three ways. Some plants avoid the stress altogether (e.g. ephemeral, short-lived, desert plants), some show susceptibility to stress which may ultimately lead to plant death and some show resistant capacity [13]. To defend themselves against diverse stresses, plants have evolved complicated and highly regulated systems. To cope with these challenging environment plants evolve some efficient mechanism such as adjustment in photosynthetic rates, stomatal conductance, transpiration, cell wall architecture, remodeling of membrane structure, alterations in cell cycle and division rates with overall effect on general growth to fine-tune physiology and metabolism of bioactive compounds [14]. Initiation of stress and defense responses are mediated by signaling processes and pathways which trigger the primary metabolism that provides biosynthetic intermediates for secondary metabolism in plant body. These include the stress responsive system and the inducible defense system which depends on inducible activation of massive defense-related genes, suit of molecular and cellular process as well as inducible production of diverse defense-related SMs [15]. Plant accumulate a large number of SMs from primary metabolites in cells, and the production of that metabolites are regarded as an adaptive capacity in coping with stressful constraints

Generally, a stress signal transduction pathway comprises the following key steps: (i) signal perception; (ii) signal transduction; and (iii) stress response. The first step in the activation of signaling cascade for any given stress is the recognition of stress signals via receptors located on the membrane of plant cell. Recently a few research works indicated that various plasma membrane proteins like COLD1 (Chilling Tolerance Divergence-1) [19], CNGCs (cyclic nucleotide nucleotidegated channel), GLR (glutamate-receptor like) channel, histidine kinases, calcium channel are the main sensors for stress signaling. After recognition, the receptors transmit the signal into downstream through phytohormones and second messengers such as Ca2+ and ROS [20]. The second messengers, like ROS, trigger the activation of another set of ROS-modulated protein kinases (PKs) and protein phosphatases (PPs), including MAPK (mitogen-activated protein kinase) cascades, CDPKs (calcium-dependent protein kinases), CBLs (calcineurin-B-like proteins), CIPK (CBL-interacting protein kinase), and many other PKs as well as PPs such as some PP2Cs (protein phosphatase 2Cs). Subsequently, these PKs and PPs deliver the information downstream and trigger a series of phosphorylation or dephosphorylation of transcription factors (TFs), that finally culminates either directly in the

tion of various biotic and abiotic stresses in plants has been discussed.

**548**

expression of functional genes involved in cellular protection, or indirectly in the expression of regulatory genes participating in signaling cascades and transcriptional regulation of gene expression.

In addition of the enzymatic (such as superoxide dismutase, catalase, ascorbate peroxidase) and non-enzymatic antioxidants (such as ascorbic acid, reduced glutathione, α-tocopherol, carotenoids, flavonoids), primary metabolites including sugars, amino acids contribute to cellular homeostasis to adapt under stressful conditions [21]. Recently, the research advances supporting that products of secondary metabolism are important to alleviate toxic effects of stresses [5] through expression of stress responsive genes. Therefore, in presence of stress signals accumulated various species of SMs are critically important for adaptation and tolerance to the altering environment.

## **4. Generation and diversity of secondary metabolites in plants**

Plant SMs are classified into four major categories. These four categories include (i) terpenes (such as carotenoids, sterols, cardiac glycosides and plant volatiles), (ii) phenolics (such as lignans, phenolic acid, tannins, coumarins, lignins, stilbenes and flavonoids), (iii) nitrogen containing compounds (such as cyanogenic glycosides, alkaloids, and glucosinolates) and (iv) sulfur containing compounds (such as glutathione, phytoalexins, thionins, defensins and lectins) [22, 23]. But on the basis of biosynthesis pathways plant SMs are usually classified into three chemically distinct groups [24]. The diverse chemical structures of the SMs determine their functions to the medicine and stress adaptation. Three major categories are (i) terpenes derived from mevalonic acid pathway [25] and methyl erythritol phosphate pathway [26], (ii) phenolics derived from malonic acid pathway or a few case shikimic acid pathway [27], (iii) N (Nitrogen) and S (Sulfur) containing compounds via tricarboxylic acid cycle or sometimes via shikimic acid pathway. Among the pathways of SMs accumulation, shikimic acid, mevalonic acid, phenylpropanoic acid and methyl erythritol phosphate pathways are highly regulated under stress stimuli.

## **5. Terpenes for stress responses in plant**

Plants produce various types of SMs, many of which have been subsequently exploited by humans for their beneficial roles in a diverse array of biological functions [28]. Terpenes are one of the diverse species of SMs contribute to the various biological process in plants. Terpenoids are terpenes with an oxygen moiety and additional structural rearrangements. Therefore, these two terms of terpenes and terpenoids are used interchangeably. Terpenoids have their roles in plant defense against biotic and abiotic stresses or they are treated as signal molecules to attract the insects for pollination. The first step of terpenoid biosynthesis is generation of C5 unit like as isopentenyl diphosphate (IPP) or dimethylallyl diphosphate (DMAPP). On the basis of C5 units, we can classify the terpenoids as C5 (hemiterpenes), C10 (monoterpenes), C15 (sesquiterpenes), C20 (diterpenes), C25 (sesterpenes), C30 (triterpenes), C40 (tetraterpenes), C40 (polyterpenes) [29–31].

#### **5.1 Terpenes for biotic stress responses**

The rate of terpene emission in *Pinus sylvestris subsp. nevadensis* is increased due to attack of the caterpillar of Pine Processionary Moth (PPM). PPM is the main

defoliator of pine tree in the mediterranean region. The emission rates of terpenes are higher in attacked branches of trees than non-attacked trees. That indicates, terpenes are toxic volatile compounds accumulate in plant to provide sufficient defense mechanism [32]. Terpenoids can serve as repellents and reduce larval feeding and oviposition by herbivores [33, 34]. Isoprene is volatile organic compound and belongs to the terpenoids group. *Manduca sexta* caterpillars were released to the transgenic tobacco plants containing isoprene synthase gene and the wild type of which does not emit isoprene. This study showed that isoprene-emitting transgenic tobacco plants deters *Manduca sexta* from feeding [35].

In attack of root feeding herbivore, plant produce various types of metabolites such as sesquiterpene lactone taraxinic acid β-D glucopyranosyl ester (TA-G) [36]. The main function of these compounds is to protect the plant against below ground herbivore attack. Dandelion (*Taraxacum officinale*) is known to release secondary metabolite-rich latex from wounded roots which help to protect this plant from its native root feeding enemy, larvae of the common cockchafer beetle (*Melolontha melolontha*). A study showed that TA-G-deficient lines lost more main and side root mass than control lines after 10 d of feeding by *M. melolontha* relative to undamaged control plants [37].

#### **5.2 Terpenes for abiotic stress responses**

Under abiotic stress conditions volatile terpenes alleviate the effects of oxidative stress either through direct reactions with oxidant intercellularly, and alteration of ROS signaling. The amphipathic nature of isoprene enhances hydrophobic interactions between membrane proteins and lipids [38] which prevents membrane disintegration and protein disintegration. In response to oxidative stimuli, membrane bound SMs such as such as tocopherol and carotenoids (zeaxanthin, neoxanthin, and lutein) acts as antioxidants and may directly scavenge ROS in response to photoinhibition [39–43]. Singlet oxygen generated under oxidative stress considered is one of the strong oxidants also removed by the isoprenoids [44]. Oleuropein, a member of terpene family SMs, found higher amount of accumulation in leaves and roots of olive tree in response to salinity stress. The increase accumulation of oleuropein under salinity stress protect the olive tree from the oxidative stress [45]. The reason behind this relationship is that oleuropein acts as a glucose-reservoir for osmoregulation or high energy-consuming processes required for plant adaptation to salinity. Furthermore, oleuropein may act as an additional constituent of the antioxidant defense system of olive trees. Although most studies showed plant tolerant mechanism largely depends on the functions of non-volatiles antioxidant compounds. However, various volatiles organic compounds of the terpenes family have been connected in the protection to abiotic stresses, in particular photooxidative stress, heat stress and ozone stress. In response to ozone and heat stress, plant emitting isoprene alleviate ROS accumulation and protected plant from oxidative damages. Grapevines are not isoprene emitting plants but other volatiles isoprenoids such as monoterpenes emitter grapevine clone showed tolerance to heat stress [46].

Among the terpenes, isoprene (C5) and monoterpene hydrocarbons ameliorate abiotic stress in a number of plant species via membrane stabilization and direct antioxidant effects. Besides antioxidants properties of isoprene and monoterpene hydrocarbons they also rapid react with ozone to reduce its toxicity. A transgenic tobacco (*Nicotiana attenuata*) overexpressing a maize terpene synthase gene (ZmTPS10) might protected plants from intermitted heat stress by the accumulation of sesquiterpene hydrocarbons (C15) (E)-ß-farnesene and (E)-α-bergamotene [47–49]. Rice seedlings exposed to UV-B radiation and hydrogen peroxide accumulated higher amount of dozens of monoterpenes such as limonene, sabinene and myrcene to adapt in the altering environment [50].

**551**

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants*

Zealexins and kauralexins are two acidic terpenoid phytoalexins mediate biotic

Phenolics are one of the most ubiquitous groups of SMs which are synthesize in plants and possess biological properties like antifeedant [53], antioxidant, antiapoptosis, anti-aging, anticarcinogenic, anti-inflammation, and cell proliferation activity. Phenolics consist of an aromatic ring with one or more hydroxyl groups. Coumarin, furano-coumarins, lignin, flavonoids, isoflavonoids and tanins are the available forms of phenolics. Phenolics are often produced and accumulated in the sub-epidermal layers of plant tissues exposed to stress and pathogen attack [54]. The concentration of a particular phenolic compound within a plant tissue is dependent on season and may also vary at different stages of growth and development [55]. Several internal and external factors, including trauma, wounding, drought and pathogen attack, affect the synthesis and accumulation of phenolics [56, 57].

Phenolics are ubiquitous SMs in plants serves as a protective agent, inhibitors, natural animal toxicants and pesticides against invading herbivores, nematodes, phytophagous insects, and fungal and bacterial pathogens [58, 59]. Among the phenolic compounds coumarins are simple phenolic widespread in vascular plants and appear to function in different capacities in various plant defense mechanisms against insect herbivores and fungi. Several studies in many different plant species have shown that coumarins can accumulate in response to infection by a diversity of pathogens, including viruses, bacteria, fungi and oomycetes. The extent and timing of coumarin accumulation in plant parts have been associated with the level of disease resistance [60, 61]. The phenolic compounds ferulic acid and protocatecuic acid are accumulated increasingly in rice by the fungal attack to reduce mycotoxin. The accumulation of these two phenolics are positively correlated with *p*-coumaric

acid and 4-hydroxybenzoic acid to protect plant from mycotoxin [62].

The accumulation of phenolics in plant tissues is considered as an adaptive response of plants to adverse environmental conditions. In response to various external stimuli plant cell increases accumulation of phenolic substances. Therefore, the degree of interactions between plants and their changing environments has been a major driving force behind the emergence of specific natural products. For example, cold stress increases phenolic production into the cell wall in winter rye (*Secale cereale*) either as suberin or lignin. Lignification and suberin

damages caused by insect and pathogen in aboveground part of maize plants. Recently it is showed that terpenoid phytoalexins also protect root damages under abiotic stress factors such as drought and salinity stress. Wild type maize plant accumulated terpenoid phytoalexins are positively correlated with the biomass accumulation of the plants. On the other side, mutant maize deficient with kauralexin synthesis are sensitive to water deficit condition [51]. Carnosic acid (CA), a diterpene protect Labiatae species from water stress-induced oxidative damages in combination with that of other low-molecular weight antioxidants (α-tocopherol and ascorbate) in chloroplasts [52]. These findings suggest that terpenes protect plants from biotic and abiotic stress damages due to their antioxidant properties or

*DOI: http://dx.doi.org/10.5772/intechopen.95495*

direct quenching of oxidants.

**6. Phenolics for stress responses in plant**

**6.1 Phenolics for biotic stress responses**

**6.2 Phenolics for abiotic stress responses**

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants DOI: http://dx.doi.org/10.5772/intechopen.95495*

*Antioxidants - Benefits, Sources, Mechanisms of Action*

tobacco plants deters *Manduca sexta* from feeding [35].

**5.2 Terpenes for abiotic stress responses**

myrcene to adapt in the altering environment [50].

defoliator of pine tree in the mediterranean region. The emission rates of terpenes are higher in attacked branches of trees than non-attacked trees. That indicates, terpenes are toxic volatile compounds accumulate in plant to provide sufficient defense mechanism [32]. Terpenoids can serve as repellents and reduce larval feeding and oviposition by herbivores [33, 34]. Isoprene is volatile organic compound and belongs to the terpenoids group. *Manduca sexta* caterpillars were released to the transgenic tobacco plants containing isoprene synthase gene and the wild type of which does not emit isoprene. This study showed that isoprene-emitting transgenic

In attack of root feeding herbivore, plant produce various types of metabolites such

Under abiotic stress conditions volatile terpenes alleviate the effects of oxidative stress either through direct reactions with oxidant intercellularly, and alteration of ROS signaling. The amphipathic nature of isoprene enhances hydrophobic interactions between membrane proteins and lipids [38] which prevents membrane disintegration and protein disintegration. In response to oxidative stimuli, membrane bound SMs such as such as tocopherol and carotenoids (zeaxanthin, neoxanthin, and lutein) acts as antioxidants and may directly scavenge ROS in response to photoinhibition [39–43]. Singlet oxygen generated under oxidative stress considered is one of the strong oxidants also removed by the isoprenoids [44]. Oleuropein, a member of terpene family SMs, found higher amount of accumulation in leaves and roots of olive tree in response to salinity stress. The increase accumulation of oleuropein under salinity stress protect the olive tree from the oxidative stress [45]. The reason behind this relationship is that oleuropein acts as a glucose-reservoir for osmoregulation or high energy-consuming processes required for plant adaptation to salinity. Furthermore, oleuropein may act as an additional constituent of the antioxidant defense system of olive trees. Although most studies showed plant tolerant mechanism largely depends on the functions of non-volatiles antioxidant compounds. However, various volatiles organic compounds of the terpenes family have been connected in the protection to abiotic stresses, in particular photooxidative stress, heat stress and ozone stress. In response to ozone and heat stress, plant emitting isoprene alleviate ROS accumulation and protected plant from oxidative damages. Grapevines are not isoprene emitting plants but other volatiles isoprenoids such as monoterpenes emitter grapevine clone showed tolerance to heat stress [46]. Among the terpenes, isoprene (C5) and monoterpene hydrocarbons ameliorate abiotic stress in a number of plant species via membrane stabilization and direct antioxidant effects. Besides antioxidants properties of isoprene and monoterpene hydrocarbons they also rapid react with ozone to reduce its toxicity. A transgenic tobacco (*Nicotiana attenuata*) overexpressing a maize terpene synthase gene (ZmTPS10) might protected plants from intermitted heat stress by the accumulation of sesquiterpene hydrocarbons (C15) (E)-ß-farnesene and (E)-α-bergamotene [47–49]. Rice seedlings exposed to UV-B radiation and hydrogen peroxide accumulated higher amount of dozens of monoterpenes such as limonene, sabinene and

as sesquiterpene lactone taraxinic acid β-D glucopyranosyl ester (TA-G) [36]. The main function of these compounds is to protect the plant against below ground herbivore attack. Dandelion (*Taraxacum officinale*) is known to release secondary metabolite-rich latex from wounded roots which help to protect this plant from its native root feeding enemy, larvae of the common cockchafer beetle (*Melolontha melolontha*). A study showed that TA-G-deficient lines lost more main and side root mass than control lines after 10 d of feeding by *M. melolontha* relative to undamaged control plants [37].

**550**

Zealexins and kauralexins are two acidic terpenoid phytoalexins mediate biotic damages caused by insect and pathogen in aboveground part of maize plants. Recently it is showed that terpenoid phytoalexins also protect root damages under abiotic stress factors such as drought and salinity stress. Wild type maize plant accumulated terpenoid phytoalexins are positively correlated with the biomass accumulation of the plants. On the other side, mutant maize deficient with kauralexin synthesis are sensitive to water deficit condition [51]. Carnosic acid (CA), a diterpene protect Labiatae species from water stress-induced oxidative damages in combination with that of other low-molecular weight antioxidants (α-tocopherol and ascorbate) in chloroplasts [52]. These findings suggest that terpenes protect plants from biotic and abiotic stress damages due to their antioxidant properties or direct quenching of oxidants.

## **6. Phenolics for stress responses in plant**

Phenolics are one of the most ubiquitous groups of SMs which are synthesize in plants and possess biological properties like antifeedant [53], antioxidant, antiapoptosis, anti-aging, anticarcinogenic, anti-inflammation, and cell proliferation activity. Phenolics consist of an aromatic ring with one or more hydroxyl groups. Coumarin, furano-coumarins, lignin, flavonoids, isoflavonoids and tanins are the available forms of phenolics. Phenolics are often produced and accumulated in the sub-epidermal layers of plant tissues exposed to stress and pathogen attack [54]. The concentration of a particular phenolic compound within a plant tissue is dependent on season and may also vary at different stages of growth and development [55]. Several internal and external factors, including trauma, wounding, drought and pathogen attack, affect the synthesis and accumulation of phenolics [56, 57].

#### **6.1 Phenolics for biotic stress responses**

Phenolics are ubiquitous SMs in plants serves as a protective agent, inhibitors, natural animal toxicants and pesticides against invading herbivores, nematodes, phytophagous insects, and fungal and bacterial pathogens [58, 59]. Among the phenolic compounds coumarins are simple phenolic widespread in vascular plants and appear to function in different capacities in various plant defense mechanisms against insect herbivores and fungi. Several studies in many different plant species have shown that coumarins can accumulate in response to infection by a diversity of pathogens, including viruses, bacteria, fungi and oomycetes. The extent and timing of coumarin accumulation in plant parts have been associated with the level of disease resistance [60, 61]. The phenolic compounds ferulic acid and protocatecuic acid are accumulated increasingly in rice by the fungal attack to reduce mycotoxin. The accumulation of these two phenolics are positively correlated with *p*-coumaric acid and 4-hydroxybenzoic acid to protect plant from mycotoxin [62].

#### **6.2 Phenolics for abiotic stress responses**

The accumulation of phenolics in plant tissues is considered as an adaptive response of plants to adverse environmental conditions. In response to various external stimuli plant cell increases accumulation of phenolic substances. Therefore, the degree of interactions between plants and their changing environments has been a major driving force behind the emergence of specific natural products. For example, cold stress increases phenolic production into the cell wall in winter rye (*Secale cereale*) either as suberin or lignin. Lignification and suberin

deposition increase resistance to cold stress. These cell wall thickenings protect the plant from freezing stress. An increase in cell wall thickening could reduce cell collapse during freezing-induced dehydration and mechanical stress, thus providing freezing resistance to the plant [63]. Inhibition of root growth was recorded due to the accumulation of soluble phenolics and higher lignification in cucumber. Soluble phenolic compounds increased with time at chilling temperature but after rewarming these were decreased slightly. The decreased level in both organs (hypocotyl and root) after rewarming may suggest their important role in protection of both soybean organs against chilling injury. These compounds may participate in auxin metabolism, change membrane permeability, influence respiration and oxidative phosphorylation or protein synthesis [64].


#### **Table 1.**

*Nature of responses of phenolic compounds to abiotic stress in some plant species.*

**553**

bacterial membranes [77].

**Table 1**.

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants*

Exposure of ambient solar UV-B radiation to plants in open fields adversely affects macromolecules through the generation of ROS. At the same time, plants synthesize phenolic compounds, which act as a screen inside the epidermal cell layer to defend themselves from this damaging radiation and by adjusting the antioxidant systems at both the cell and whole organism level. A comparative accumulation of phenolics were measured after UV irradiation in buckwheat genotypes (*Fagopyrum esculentum and F. tataricum*) and found a specific increase of quercetin concentration in *F. esculentum* [65]. Drought is the major abiotic stress that affects plant growth and development and causes losses in agricultural production. As has been reported by several studies, phenolics content increased in plants under water scarcity to improve drought tolerance in *Arabidopsis thaliana* [66]. Tolerant and sensitive rice cultivars to salinity showed variable amount of phenolic compounds. A large increase of total phenolics and the content of protocatechuic acid was found in tolerant varieties, whereas in contrast, a markedly reduce was found in the susceptible cultivar [67]. In addition, the content of flavonoids and chlorogenic acid are positively correlated to the growth-lighting condition in Australian *Centella* 

Certain flavonoids exhibit the ability to provide heavy metal stress protection by transition metals chelation (e.g., Fe, Cu, Ni, Zn), which generates hydroxyl radical via Fenton's reaction revealed that the chelation of these metals in the soil may be an effective form of defense against the effects of high metals concentration toxicity. The biosynthesis of phenolic compounds that are precursors of lignin intensifies under stress conditions [69]. Research on corn plants (*Zea mays* L.) confirmed this phenomenon when grown on soil contaminated with aluminum ions and root exudates were found with high levels of catechin and quercetin. Phenolic compounds also contribute to reduce heavy metal toxicity in plants. Cadmium metalstressed *Brassica juncea* plants accumulated higher amount of rutin polyphenol than untreated plants to prevent oxidative damages [70]. Phenolic compounds were related to the antioxidant activity, and they play a major role in stabilizing lipid peroxidation. Actually during stress condition plants become potentially active and by releasing phenolic substance, modulating the activities of antioxidants, enzyme activities, and radicals scavenging activities demonstrated their active participation in oxidative stress management [71]. Some other evidences of nature of responses of phenolic compounds to abiotic stress in some plant species are summarized in

**7. N and S containing SMs for stress responses in plant**

them are biosynthesized from common amino acids.

**7.1 N and S containing SMs for biotic stress responses**

A large family of N and S containing SMs found in approximately 20% of the species of vascular plants, most frequently in the herbaceous dicot and relatively a few in monocots and gymnosperms. They include alkaloids, cyanogenic glucosides, non-protein amino acids phytoalexins, thionine, defensins and allinin. Most of

Alkaloids are nitrogenous organic SMs that have been shown to have antimicrobial activity (such as quinolones, metronidazole, or others) through inhibiting enzyme activity or other mechanisms. Squalamine, a polyamine alkaloid, acts through a detergent-like mechanism of action against gram-negative bacteria, leading to the disruption of their outer membranes, and it depolarizes gram-positive

*DOI: http://dx.doi.org/10.5772/intechopen.95495*

*asiatica* (L.) *Urb* [68].

#### *Role of Secondary Metabolites to Attenuate Stress Damages in Plants DOI: http://dx.doi.org/10.5772/intechopen.95495*

*Antioxidants - Benefits, Sources, Mechanisms of Action*

phosphorylation or protein synthesis [64].

**Nature of response**

Increase accumulation and tolerance level

Increase accumulation and tolerance level

Increased accumulation and tolerance level

tolerance level

accumulation

Decreased accumulation and tolerance level

Increased accumulation, become drought resistant

deposition provide protection from damaging light

accumulation and become resistant against heavy metal

deposition and become freezing resistant

*Nature of responses of phenolic compounds to abiotic stress in some plant species.*

Increase accumulation and tolerance level

**Metabolic name of** 

Coniferyl alcohol, ferulic acid and p-coumaric

Chlorogenic acid, apigenin and luteolin

Chlorogenic acid, rutin, hyperoside, isoquercetine, quercitrine and quercetine

Flavonols and hydroxycinnamic acids

Flavonoids, isoflavonoids

Protocatecuic acid Increased

Chlorogenic acid Increased

Quercetin Increased level of

Catechin and quercetin Increased

Lignin or suberin Increased

Caffeic acid, p-coumaric acid and ferulic acid

**phenol**

deposition increase resistance to cold stress. These cell wall thickenings protect the plant from freezing stress. An increase in cell wall thickening could reduce cell collapse during freezing-induced dehydration and mechanical stress, thus providing freezing resistance to the plant [63]. Inhibition of root growth was recorded due to the accumulation of soluble phenolics and higher lignification in cucumber. Soluble phenolic compounds increased with time at chilling temperature but after rewarming these were decreased slightly. The decreased level in both organs (hypocotyl and root) after rewarming may suggest their important role in protection of both soybean organs against chilling injury. These compounds may participate in auxin metabolism, change membrane permeability, influence respiration and oxidative

> Nutrient deficiency

Salinity *S. macrosiphon*

Heat stress, salinity stress

Drought *Arabidopsis thaliana*

Cold stress/free

zing

Drought stress *Capsicum* 

Salinity *Hypericum* 

**Abiotic stress Plant species Reference**

Reviewed in various plant species

*annuum L.*

*pruinatum*

Valifard et al. [67]

*Solanum lycopersicon cv. Boludo*

Full sunlight *V. myrtillus* Alqahtani

Nakabayashi et al. [66]

Drought *Vitis vinifera* L. Kro'l

UV *F. esculentum* Regvar

Heavy metal *Zea mays L* Michalak

Ahagnar et al. [72]

Rodríguez-Calzada et al. [73]

Caliskan et al. [74]

Martinez et al. [75]

et al. [68]

et al. [76]

*et al*. [65]

[69]

Yaish [63]

*Secale cereal* Griffith and

**552**

**Table 1.**

Exposure of ambient solar UV-B radiation to plants in open fields adversely affects macromolecules through the generation of ROS. At the same time, plants synthesize phenolic compounds, which act as a screen inside the epidermal cell layer to defend themselves from this damaging radiation and by adjusting the antioxidant systems at both the cell and whole organism level. A comparative accumulation of phenolics were measured after UV irradiation in buckwheat genotypes (*Fagopyrum esculentum and F. tataricum*) and found a specific increase of quercetin concentration in *F. esculentum* [65]. Drought is the major abiotic stress that affects plant growth and development and causes losses in agricultural production. As has been reported by several studies, phenolics content increased in plants under water scarcity to improve drought tolerance in *Arabidopsis thaliana* [66]. Tolerant and sensitive rice cultivars to salinity showed variable amount of phenolic compounds. A large increase of total phenolics and the content of protocatechuic acid was found in tolerant varieties, whereas in contrast, a markedly reduce was found in the susceptible cultivar [67]. In addition, the content of flavonoids and chlorogenic acid are positively correlated to the growth-lighting condition in Australian *Centella asiatica* (L.) *Urb* [68].

Certain flavonoids exhibit the ability to provide heavy metal stress protection by transition metals chelation (e.g., Fe, Cu, Ni, Zn), which generates hydroxyl radical via Fenton's reaction revealed that the chelation of these metals in the soil may be an effective form of defense against the effects of high metals concentration toxicity. The biosynthesis of phenolic compounds that are precursors of lignin intensifies under stress conditions [69]. Research on corn plants (*Zea mays* L.) confirmed this phenomenon when grown on soil contaminated with aluminum ions and root exudates were found with high levels of catechin and quercetin. Phenolic compounds also contribute to reduce heavy metal toxicity in plants. Cadmium metalstressed *Brassica juncea* plants accumulated higher amount of rutin polyphenol than untreated plants to prevent oxidative damages [70]. Phenolic compounds were related to the antioxidant activity, and they play a major role in stabilizing lipid peroxidation. Actually during stress condition plants become potentially active and by releasing phenolic substance, modulating the activities of antioxidants, enzyme activities, and radicals scavenging activities demonstrated their active participation in oxidative stress management [71]. Some other evidences of nature of responses of phenolic compounds to abiotic stress in some plant species are summarized in **Table 1**.

## **7. N and S containing SMs for stress responses in plant**

A large family of N and S containing SMs found in approximately 20% of the species of vascular plants, most frequently in the herbaceous dicot and relatively a few in monocots and gymnosperms. They include alkaloids, cyanogenic glucosides, non-protein amino acids phytoalexins, thionine, defensins and allinin. Most of them are biosynthesized from common amino acids.

#### **7.1 N and S containing SMs for biotic stress responses**

Alkaloids are nitrogenous organic SMs that have been shown to have antimicrobial activity (such as quinolones, metronidazole, or others) through inhibiting enzyme activity or other mechanisms. Squalamine, a polyamine alkaloid, acts through a detergent-like mechanism of action against gram-negative bacteria, leading to the disruption of their outer membranes, and it depolarizes gram-positive bacterial membranes [77].

Phytoalexins are S containing SMs, in response to fungal and bacterial pathogen, other forms of stress such as mechanical damages accumulate in the infection sites. The accumulation of phytoalexins limit the spreading of pathogen by inducing cell death known as hypersensitive response (HR) in a diverse group of plants. Defensins, thionins and lectins S-rich SMs accumulate in pathogen attack and external injury. These compounds also showed broad range of inhibition of microbial pathogen such as fungi and bacteria [78]. Glucosinolates are sulfur-rich SMs, widely synthesized in all vegetable and oilseed species of the order Brassicales (*Brassica oleracea*). The enzyme myrosinase (thioglucosidase) are stored in special myrosinase cells. When the tissue damage is commenced due to insect feeding, this enzyme comes into contact with glucosinolates and hydrolyses indole glucosinolates to produce nitriles and unstable isothiocyanates and aliphatic glucosinolates to produce volatile and pungent isothiocyanates. These products have toxic properties that inhibits growth (antibiosis) and act as feeding deterrents (antixenosis) against a range of insects; from leaf chewing lepidopteran larvae to phloem-feeding aphids [79]. Glucosinolate accumulation by the attack of diamondback moth insect on cabbage protect the plant by creating toxicity [80].

### **7.2 N and S containing SMs for abiotic stress responses**

Alkaloids are N containing SMs also trigger adaption mechanism of plants. The concentration of four kind of alkaloids such as vindoline, catharanthine, vinblastine and vincristine significantly increased with the increasing saline concentration but the total dry weight to some extent were decreased. The reduction in plant growth may be an adaptive response to salt stress which allows the conservation of energy, thereby launching the appropriate defense response and also reducing the risk of heritable damage [81]. To adapt in the water scarcity stress *Senecio jacobaea*, *Senecio aquaticus*, and their hybrids increased the accumulation of pyrrolizidine alkaloids (PAs) [82]. The influence of drought stress changes the contents of alkaloids such as narkotine, morphine, codeine in *Papaver somniferum.* The comparison to the control group demonstrated that alkaloids narkotine and morphine trigger tolerance mechanism of plants [83]. The contents of alkaloids such as vindoline, catharanthine and vinblastine were significantly increased in the seedling leaves of *Catharanthus roseus* under short exposure of heat stress. Therefore, accumulation of alkaloids species under stressful conditions are critically important to adapt in the altering environments.

## **8. Conclusion**

Plant tolerance to stresses is jointly controlled by the plants' anatomy, physiology, biochemistry, genetics, development and evolution. In addition to the primary metabolites, in response to various stresses either biotic and abiotic plants start to synthesize SMs in their cell. As a result, some physiological modification such as metabolic adjustment, ion and water balance, regulation of stomatal conductance, activation of different types of antioxidant and enzyme occurs which help the plant to increase tolerance level. Plant tolerance and adaptation mechanism to stressful conditions are mainly adjusted by the modifying primary metabolism pathway. According to the aforementioned data, SMs functions on stress adaptation are established in the recent year. Therefore, manipulating the generation and action of SMs and the activity of genes responsible for the accumulation of SMs are critically important to enhance the tolerance level and adaptability of plants under stressful conditions.

**555**

**Author details**

Masuma Zahan Akhi1

University, Gazipur, Bangladesh

Agricultural University, Gazipur, Bangladesh

provided the original work is properly cited.

\*Address all correspondence to: sanaullah@bsmrau.edu.bd

, Md. Manjurul Haque2

1 Department of Horticulture, Bangabandhu Sheikh Mujibur Rahman Agricultural

2 Department of Environmental Science, Bangabandhu Sheikh Mujibur Rahman

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

and Md. Sanaullah Biswas1

\*

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants*

*DOI: http://dx.doi.org/10.5772/intechopen.95495*

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants DOI: http://dx.doi.org/10.5772/intechopen.95495*

*Antioxidants - Benefits, Sources, Mechanisms of Action*

cabbage protect the plant by creating toxicity [80].

**7.2 N and S containing SMs for abiotic stress responses**

Phytoalexins are S containing SMs, in response to fungal and bacterial pathogen, other forms of stress such as mechanical damages accumulate in the infection sites. The accumulation of phytoalexins limit the spreading of pathogen by inducing cell death known as hypersensitive response (HR) in a diverse group of plants. Defensins, thionins and lectins S-rich SMs accumulate in pathogen attack and external injury. These compounds also showed broad range of inhibition of microbial pathogen such as fungi and bacteria [78]. Glucosinolates are sulfur-rich SMs, widely synthesized in all vegetable and oilseed species of the order Brassicales (*Brassica oleracea*). The enzyme myrosinase (thioglucosidase) are stored in special myrosinase cells. When the tissue damage is commenced due to insect feeding, this enzyme comes into contact with glucosinolates and hydrolyses indole glucosinolates to produce nitriles and unstable isothiocyanates and aliphatic glucosinolates to produce volatile and pungent isothiocyanates. These products have toxic properties that inhibits growth (antibiosis) and act as feeding deterrents (antixenosis) against a range of insects; from leaf chewing lepidopteran larvae to phloem-feeding aphids [79]. Glucosinolate accumulation by the attack of diamondback moth insect on

Alkaloids are N containing SMs also trigger adaption mechanism of plants. The concentration of four kind of alkaloids such as vindoline, catharanthine, vinblastine and vincristine significantly increased with the increasing saline concentration but the total dry weight to some extent were decreased. The reduction in plant growth may be an adaptive response to salt stress which allows the conservation of energy, thereby launching the appropriate defense response and also reducing the risk of heritable damage [81]. To adapt in the water scarcity stress *Senecio jacobaea*, *Senecio aquaticus*, and their hybrids increased the accumulation of pyrrolizidine alkaloids (PAs) [82]. The influence of drought stress changes the contents of alkaloids such as narkotine, morphine, codeine in *Papaver somniferum.* The comparison to the control group demonstrated that alkaloids narkotine and morphine trigger tolerance mechanism of plants [83]. The contents of alkaloids such as vindoline, catharanthine and vinblastine were significantly increased in the seedling leaves of *Catharanthus roseus* under short exposure of heat stress. Therefore, accumulation of alkaloids species under stressful conditions are critically important to adapt in the

Plant tolerance to stresses is jointly controlled by the plants' anatomy, physiology, biochemistry, genetics, development and evolution. In addition to the primary metabolites, in response to various stresses either biotic and abiotic plants start to synthesize SMs in their cell. As a result, some physiological modification such as metabolic adjustment, ion and water balance, regulation of stomatal conductance, activation of different types of antioxidant and enzyme occurs which help the plant to increase tolerance level. Plant tolerance and adaptation mechanism to stressful conditions are mainly adjusted by the modifying primary metabolism pathway. According to the aforementioned data, SMs functions on stress adaptation are established in the recent year. Therefore, manipulating the generation and action of SMs and the activity of genes responsible for the accumulation of SMs are critically important to enhance the toler-

ance level and adaptability of plants under stressful conditions.

**554**

altering environments.

**8. Conclusion**

## **Author details**

Masuma Zahan Akhi1 , Md. Manjurul Haque2 and Md. Sanaullah Biswas1 \*

1 Department of Horticulture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh

2 Department of Environmental Science, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh

\*Address all correspondence to: sanaullah@bsmrau.edu.bd

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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[19] Ma Y, Dai X, Xu Y, Luo W, Zheng X, Zeng D, Pan Y, Lin X, Liu H, Zhang D, Xiao J. COLD1 confers chilling tolerance in Rice. Cell. 2015;160:1209-1221. DOI: 10.1016/j.cell.2015.01.046.

[20] Mahajan S, Pandey GK, Tuteja N. Calcium-and salt-stress signaling in plants: shedding light on SOS pathway. Archives of Biochemistry and Biophysics. 2008;471:146-158. DOI: 10.1016/j.abb.2008.01.010

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**556**

*Antioxidants - Benefits, Sources, Mechanisms of Action*

in plant innate immunity: conserved function of divergent chemicals. New Phytologist. 2015;206:948-964. DOI:

[9] Mano J, Biswas MS, Sugimoto K. Reactive carbonyl species: a missing link in ROS signaling. Plants. 2019; 8:391.

[10] Biswas MS, Mano J. Lipid peroxidederived short-chain carbonyls mediate hydrogen peroxide-induced and salt-induced programmed cell death in plants. Plant Physiology. 2015;168: 885-898. DOI: 10.1104/pp.115.256834

[11] Biswas MS, Mano, J. Reactive carbonyl species activate caspase-3 like protease to initiate programmed cell death in plants. Plant and Cell Physiology. 2016;57:1432-1442. DOI:

[12] Kurutas EB, Ozturk P. The

stress in patients with pityriasis versicolor: a preliminary study.

10.1007/s11103-008-9416-3

[14] Atkinson NJ, Urwin PE. The interaction of plant biotic and abiotic stresses: from genes to the field. Journal of Experimental Botany. 2012;63:3523-

3543. DOI: 10.1093/jxb/ers100

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[16] Akula R, Ravishankar GA. Influence of abiotic stress signals on secondary metabolites in plants. Plant Signaling

evaluation of local oxidative/nitrosative

Mycoses. 2016;59:720-725. DOI: 10.1111/

[13] Shimizu-Sato S, Tanaka M, Mori H. Auxin–cytokinin interactions in the control of shoot branching. Plant Molecular Biology. 2009;69:429. DOI:

10.1093/pcp/pcw053

myc.12522

DOI: 10.3390/plants8100391

10.1111/nph.13325

[1] Bourgaud F, Gravot A, Milesi S, Gontier E. Production of plant secondary metabolites: A historical

perspective. Plant Science. 2001;161:839-851. DOI: 10.1016/

[2] Kossel A, Ueber Schleim und schleimbildende Stoffe1. DMW-

Deutsche Medizinische Wochenschrift.

[3] Jain C, Khatana S, Vijayvergia R. Bioactivity of secondary metabolites of various plants: a review. International Journal of Pharmaceutical Science and Research. 2019;10:494-504. DOI: 10.13040/IJPSR.0975-8232.10.494-04

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[6] Austen N, Lake JA, Phoenix G, Cameron DD. The regulation of plant secondary metabolism in response to abiotic stress: interactions between heat shock and elevated CO2. Frontiers in Plant Science. 2019;10:1463. DOI:

[7] Ahmad S, Nadeem S, Muhammad N. Boundary layer flow over a curved surface imbedded in porous medium. Communications in Theoretical Physics. 2019;71:344. DOI: 10.1088/0253-6102/71/3/344

[8] Piasecka A, Jedrzejczak-Rey N, Bednarek P. Secondary metabolites

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[39] Goh CH, Ko SM, Koh S, Kim YJ, Bae HJ. Photosynthesis and environments: photoinhibition and repair mechanisms in plants. Journal of Plant Biology. 2012;55:93-101. DOI: 10.1007/s12374-011-9195-2

[40] Havaux M, Eymery F, Porfirova S, Rey P, Dörmann P. Vitamin E protects against photoinhibition and photooxidative stress in Arabidopsis thaliana. The Plant Cell. 2005;17:3451- 3469. DOI: 10.1105/tpc.105.037036

[41] Havaux M, Niyogi KK. The violaxanthin cycle protects plants from photooxidative damage by more than one mechanism. Proceedings of the National Academy of Sciences. 1999;96:8762-8767. DOI: 10.1073/ pnas.96.15.8762

[42] Dall'Osto L, Fiore A, Cazzaniga S, Giuliano G, Bassi R. Different roles of α-and β-branch xanthophylls in photosystem assembly and photoprotection. Journal of Biological Chemistry. 2007;282:35056-35068. DOI: 10.1074/jbc.M704729200

[43] Peng L, Ma J, Chi W, Guo J, Zhu S, Lu Q, Lu C, Zhang L. LOW PSII ACCUMULATION1 is involved in efficient assembly of photosystem II in Arabidopsis thaliana. The Plant Cell. 2006;18:955-969. DOI: 10.1105/ tpc.105.037689

[44] Velikova V, Edreva A, Loreto F. Endogenous isoprene protects Phragmites australis leaves against singlet oxygen. Physiologia

**559**

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants*

[51] Vaughan MM, Christensen S, Schmelz EA, Huffaker A, Mcauslane HJ, Alborn HT, Romero M, Allen LH, Teal PE. Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance. Plant, Cell & Environment. 2015;38:2195-2207. DOI:

[52] Munné-Bosch S, Alegre L. Droughtinduced changes in the redox state of α-tocopherol, ascorbate, and the diterpene carnosic acid in chloroplasts of Labiatae species differing in carnosic

acid contents. Plant Physiology. 2003;131:1816-1825. DOI: 10.1104/

[53] Dar AS, Rather BA, Wani AR, Ganie MA. Resistance against Insect pests by plant phenolics and their derivative compounds. Chemical Science Review and Letters.

[54] Clé C, Hill LM, Niggeweg R, Martin CR, Guisez Y, Prinsen E, Jansen MA. Modulation of chlorogenic

acid biosynthesis in Solanum lycopersicum; consequences for phenolic accumulation and UV-tolerance. Phytochemistry. 2008;69:2149-2156. DOI: 10.1016/j.

phytochem.2008.04.024

Kashmir; 2012

[55] Dar SA. Screening of brinjal genotypes/verities against brinjal shoot and fruit borer. [thesis] Division of Entomology. SKUAST-K, Srinager,

[56] Naikoo MI, Dar MI, Raghib F, Jaleel H, Ahmad B, Raina A, Khan FA, Naushin F. Role and regulation of plants phenolics in abiotic stress tolerance: an overview. In Plant signaling molecules. 2019;157-168. Woodhead Publishing. DOI: 10.1016/

B978-0-12-816451-8.00009-5

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10.1111/pce.12482

pp.102.019265

2017;6:1073-1081

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Plantarum. 2004;122:219-225. DOI: 10.1111/j.0031-9317.2004.00392.x

[45] Petridis A, Therios I, Samouris G, Tananaki C. Salinity-induced changes in phenolic compounds in leaves and roots of four olive cultivars (*Olea europaea* L.) and their relationship to antioxidant activity. Environmental and Experimental Botany. 2012;79:37-43. DOI: 10.1016/j.envexpbot.2012.01.007

[46] Bertamini M, Grando MS, Zocca P, Pedrotti M, Lorenzi S, Cappellin L. Linking monoterpenes and abiotic stress resistance in grapevines. BIO Web of Conferences. 2019;13:01003. DOI: 10.1051/bioconf/20191301003

[47] Palmer-Young EC, Veit D, Gershenzon J, Schuman MC. The Sesquiterpenes (E)-ß-Farnesene and (E)-α-Bergamotene quench ozone but fail to protect the wild tobacco Nicotiana attenuata from ozone, UVB, and Drought Stresses. PLOS One. 2015;10:0127296. DOI: 10.1371/journal.

[48] Loreto F, Mannozzi M, Maris C, Nascetti P, Ferranti F, Pasqualini S. Ozone quenching properties of isoprene and its antioxidant role in leaves. Plant Physiology. 2001;126:993-1000. DOI:

[49] Shu Y, Atkinson R. Rate constants for the gas-phase reactions of O3 with a series of terpenes and OH radical formation from the O3 reactions with sesquiterpenes at 296±2 K. International

Journal of Chemical Kinetics. 1994;26:1193-1205. DOI: 10.1002/

[50] Lee GW, Lee S, Chung MS, Jeong YS, Chung BY. Rice terpene synthase 20 (OsTPS20) plays an important role in producing terpene volatiles in response to abiotic stresses. Protoplasma. 2015;252:997-1007. DOI:

10.1007/s00709-014-0735-8

pone.0127296

10.1104/pp.126.3.993

kin.550261207

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants DOI: http://dx.doi.org/10.5772/intechopen.95495*

Plantarum. 2004;122:219-225. DOI: 10.1111/j.0031-9317.2004.00392.x

*Antioxidants - Benefits, Sources, Mechanisms of Action*

Hammerbacher A, Triebwasser-Freese D. A latex metabolite benefits plant fitness under root herbivore attack. PLOS Biology. 2016;14:1002332. DOI: 10.1371/

journal.pbio.1002332

[38] Sharkey TD, Yeh S. Isoprene emission from plants. Annual Review of Plant Biology. 2001;52:407-436. DOI: 10.1146/annurev.arplant.52.1.407

[39] Goh CH, Ko SM, Koh S,

10.1007/s12374-011-9195-2

[40] Havaux M, Eymery F,

[41] Havaux M, Niyogi KK. The violaxanthin cycle protects plants from photooxidative damage by more than one mechanism. Proceedings of the National Academy of Sciences. 1999;96:8762-8767. DOI: 10.1073/

[42] Dall'Osto L, Fiore A, Cazzaniga S, Giuliano G, Bassi R. Different roles of α-and β-branch xanthophylls in photosystem assembly and

photoprotection. Journal of Biological Chemistry. 2007;282:35056-35068. DOI:

Zhu S, Lu Q, Lu C, Zhang L. LOW PSII ACCUMULATION1 is involved in efficient assembly of photosystem II in Arabidopsis thaliana. The Plant Cell. 2006;18:955-969. DOI: 10.1105/

Loreto F. Endogenous isoprene protects Phragmites australis leaves against singlet oxygen. Physiologia

10.1074/jbc.M704729200

[44] Velikova V, Edreva A,

[43] Peng L, Ma J, Chi W, Guo J,

pnas.96.15.8762

tpc.105.037689

Kim YJ, Bae HJ. Photosynthesis and environments: photoinhibition and repair mechanisms in plants. Journal of Plant Biology. 2012;55:93-101. DOI:

Porfirova S, Rey P, Dörmann P. Vitamin E protects against photoinhibition and photooxidative stress in Arabidopsis thaliana. The Plant Cell. 2005;17:3451- 3469. DOI: 10.1105/tpc.105.037036

diterpenes. Annual Plant Reviews Online. 2018;15:258-303. DOI: 10.1002/9781119312994.apr0427

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Brillatz T, Swyers M, Köllner TG, Vogel H,

emissions influence herbivore feeding decisions. Plant, Cell & Environment. 2008;31:1410-1415. DOI: 10.1111/j.1365-3040.2008.01849.x

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[46] Bertamini M, Grando MS, Zocca P, Pedrotti M, Lorenzi S, Cappellin L. Linking monoterpenes and abiotic stress resistance in grapevines. BIO Web of Conferences. 2019;13:01003. DOI: 10.1051/bioconf/20191301003

[47] Palmer-Young EC, Veit D, Gershenzon J, Schuman MC. The Sesquiterpenes (E)-ß-Farnesene and (E)-α-Bergamotene quench ozone but fail to protect the wild tobacco Nicotiana attenuata from ozone, UVB, and Drought Stresses. PLOS One. 2015;10:0127296. DOI: 10.1371/journal. pone.0127296

[48] Loreto F, Mannozzi M, Maris C, Nascetti P, Ferranti F, Pasqualini S. Ozone quenching properties of isoprene and its antioxidant role in leaves. Plant Physiology. 2001;126:993-1000. DOI: 10.1104/pp.126.3.993

[49] Shu Y, Atkinson R. Rate constants for the gas-phase reactions of O3 with a series of terpenes and OH radical formation from the O3 reactions with sesquiterpenes at 296±2 K. International Journal of Chemical Kinetics. 1994;26:1193-1205. DOI: 10.1002/ kin.550261207

[50] Lee GW, Lee S, Chung MS, Jeong YS, Chung BY. Rice terpene synthase 20 (OsTPS20) plays an important role in producing terpene volatiles in response to abiotic stresses. Protoplasma. 2015;252:997-1007. DOI: 10.1007/s00709-014-0735-8

[51] Vaughan MM, Christensen S, Schmelz EA, Huffaker A, Mcauslane HJ, Alborn HT, Romero M, Allen LH, Teal PE. Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance. Plant, Cell & Environment. 2015;38:2195-2207. DOI: 10.1111/pce.12482

[52] Munné-Bosch S, Alegre L. Droughtinduced changes in the redox state of α-tocopherol, ascorbate, and the diterpene carnosic acid in chloroplasts of Labiatae species differing in carnosic acid contents. Plant Physiology. 2003;131:1816-1825. DOI: 10.1104/ pp.102.019265

[53] Dar AS, Rather BA, Wani AR, Ganie MA. Resistance against Insect pests by plant phenolics and their derivative compounds. Chemical Science Review and Letters. 2017;6:1073-1081

[54] Clé C, Hill LM, Niggeweg R, Martin CR, Guisez Y, Prinsen E, Jansen MA. Modulation of chlorogenic acid biosynthesis in Solanum lycopersicum; consequences for phenolic accumulation and UV-tolerance. Phytochemistry. 2008;69:2149-2156. DOI: 10.1016/j. phytochem.2008.04.024

[55] Dar SA. Screening of brinjal genotypes/verities against brinjal shoot and fruit borer. [thesis] Division of Entomology. SKUAST-K, Srinager, Kashmir; 2012

[56] Naikoo MI, Dar MI, Raghib F, Jaleel H, Ahmad B, Raina A, Khan FA, Naushin F. Role and regulation of plants phenolics in abiotic stress tolerance: an overview. In Plant signaling molecules. 2019;157-168. Woodhead Publishing. DOI: 10.1016/ B978-0-12-816451-8.00009-5

[57] Kefeli VI, Kalevitch MV, Borsari B. Phenolic cycle in plants and environment. Journal of Cell and Molecular Biology. 2003;2:13-18

[58] Isah T. Stress and defense responses in plant secondary metabolites production. Biological Research. 2019; 52: 39. DOI: 10.1186/s40659-019-0246-3

[59] Thakur AV, Ambwani S, Ambwani TK, Ahmad AH, Rawat DS. Evaluation of phytochemicals in the leaf extract of Clitoria ternatea Willd. through GC-MS analysis. Tropical Plant Research. 2018;5:200-206. DOI: 10.22271/tpr.2018.v5.i2.025

[60] Stringlis IA, De Jonge R, Pieterse CM. The age of coumarins in plant–microbe interactions. Plant and Cell Physiology. 2019;60:1405-14019. DOI: 10.1093/pcp/pcz076

[61] Tortosa M, Cartea ME, Rodríguez VM, Velasco P. Unraveling the metabolic response of Brassica oleracea exposed to Xanthomonas campestris pv. campestris. Journal of the Science of Food and Agriculture. 2018;98:3675- 3683. DOI: 10.1002/jsfa.8876

[62] Giorni P, Rastelli S, Fregonara S, Bertuzzi T. Monitoring Phenolic Compounds in Rice during the Growing Season in Relation to Fungal and Mycotoxin Contamination. Toxins. 2020;12:341. DOI: 10.3390/ toxins12050341

[63] Griffith M, Yaish MW. Antifreeze proteins in overwintering plants: a tale of two activities. Trends in Plant Science. 2004;9:399-405. DOI: 10.1016/j. tplants.2004.06.007

[64] Posmyk MM, Bailly C, Szafrańska K, Janas KM, Corbineau F. Antioxidant enzymes and isoflavonoids in chilled soybean (*Glycine max* (L.) Merr.) seedlings. Journal of Plant Physiology. 2005;162:403-412. DOI: 10.1016/j.jplph.2004.08.004

[65] Regvar M, Bukovnik U, Likar M, Kreft I. UV-B radiation affects

flavonoids and fungal colonisation in *Fagopyrum esculentum* and *F. tataricum*. Open Life Sciences. 2012;7:275-283. DOI: 10.2478/s11535-012-0017-4

[66] Nakabayashi R, Yonekura-Sakakibara K, Urano K, Suzuki M, Yamada Y, Nishizawa T, Matsuda F, Kojima M, Sakakibara H, Shinozaki K, Michael AJ. Enhancement of oxidative and drought tolerance in Arabidopsis by overaccumulation of antioxidant flavonoids. The Plant Journal. 2014;77:367-379. DOI: 10.1111/tpj.12388

[67] Valifard M, Mohsenzadeh S, Kholdebarin B. Salinity effects on phenolic content and antioxidant activity of Salvia macrosiphon. Iranian Journal of Science and Technology. Transactions A: Science. 2017;41:295- 300. DOI: 10.1007/s40995-016-0022-y

[68] Alqahtani A, Tongkao-on W, Li KM, Razmovski-Naumovski V, Chan K, Li GQ. Seasonal variation of triterpenes and phenolic compounds in Australian *Centella asiatica* (L.) Urb. Phytochemical Analysis. 2015;26:436- 443. DOI: 10.1002/pca.2578

[69] Michalak A. Phenolic compounds and their antioxidant activity in plants growing under heavy metal stress. Polish Journal of Environmental Studies. 2006;15: 523-530.

[70] Kapoor D. Antioxidative defense responses and activation of phenolic compounds in *Brassica juncea* plants exposed to cadmium stress. International Journal of Green Pharmacy. 2016;10:228-234. DOI: 10.22377/IJGP.V10I04.760

[71] Gill SS, Tuteja N. Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants. Plant Physiology and Biochemistry. 2010;48: 909-930. DOI: 10.1016/j. plaphy.2010.08.016

[72] Ahanger MA, Bhat JA, Siddiqui MH, Rinklebe J, Ahmad P. Integration of

**561**

dkq213

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants*

metabolites of plants and their role: Overview. Current Trends in Biotechnology and Pharmacy.

[79] Santolamazza-Carbone S,

var. acephala similarly affect

Cartea ME. Antibiotic properties of the glucosinolates of Brassica oleracea

generalist and specialist larvae of two lepidopteran pests. Journal of Pest Science. 2016;89:195-206. DOI: 10.1007/

[80] Robin AH, Hossain MR, Park JI, Kim HR, Nou IS. Glucosinolate profiles in cabbage genotypes influence the preferential feeding of diamondback moth (*Plutella xylostella*). Frontiers in Plant Science. 2017;8:1244. DOI:

[81] Jing-Yan WA, Zhao-Pu LI. Alkaloid accumulation in Catharanthus roseus increases with addition of seawater salts to the nutrient solution. Pedosphere. 2010;20:718-724. DOI: 10.1016/ S1002-0160(10)60062-8

[82] Kirk H, Vrieling K, Van Der Meijden E, Klinkhamer PG. Species by environment interactions affect pyrrolizidine alkaloid expression in Senecio jacobaea, Senecio aquaticus, and their hybrids. Journal of Chemical Ecology. 2010;36:378-387. DOI: 10.1007/

[83] Yang L, Wen KS, Ruan X, Zhao YX, Wei F, Wang Q. Response of plant secondary metabolites to environmental factors. Molecules. 2018;23:762. DOI:

s10886-010-9772-8

10.3390/molecules23040762

2015;9:293-304.

Sotelo T, Velasco P,

s10340-015-0658-y

10.3389/fpls.2017.01244

*DOI: http://dx.doi.org/10.5772/intechopen.95495*

silicon and secondary metabolites in plants: a significant association in stress tolerance. Journal of Experimental Botany. 2020;71:6758-6774. DOI:

[73] Rodríguez-Calzada T, Qian M, Strid Å, Neugart S, Schreiner M,

Effect of UV-B radiation on morphology, phenolic compound production, gene expression, and subsequent drought stress responses in chili pepper (*Capsicum annuum* L.). Plant Physiology and Biochemistry. 2019;134:94-102. DOI: 10.1016/j.

[74] Caliskan O, Radusiene J,

in greenhouse-grown *Hypericum* 

[75] Martinez V, Mestre TC, Rubio F, Girones-Vilaplana A, Moreno DA, Mittler R, Rivero RM. Accumulation of Flavonols over

DOI: 10.3389/fpls.2016.00838

10.1007/s11738-014-1526-8.

Temizel KE, Staunis Z, Cirak C, Kurt D, Odabas MS. The effects of salt and drought stress on phenolic accumulation

*pruinatum*. Italian Journal of Agronomy. 2017;12. DOI: 10.4081/ija.2017.918.

Hydroxycinnamic acids favors oxidative damage protection under abiotic stress. Frontiers in Plant Science. 2016;7:838.

[76] Król A, Amarowicz R, Weidner S. Changes in the composition of phenolic compounds and antioxidant properties of grapevine roots and leaves (*Vitis vinifera* L.) under continuous of longterm drought stress. Acta Physiologia Plantarum. 2014;36:1491-1499. DOI:

[77] Alhanout K, Malesinki S, Vidal N, Peyrot V, Rolain JM, Brunel JM. New insights into the antibacterial mechanism of action of squalamine. Journal of Antimicrobial Chemotherapy. 2010;65:1688-1693. DOI: 10.1093/jac/

[78] Pagare S, Bhatia M, Tripathi N, Pagare S, Bansal YK. Secondary

Torres-Pacheco I, Guevara-González RG.

10.1093/jxb/eraa291

plaphy.2018.06.025

*Role of Secondary Metabolites to Attenuate Stress Damages in Plants DOI: http://dx.doi.org/10.5772/intechopen.95495*

silicon and secondary metabolites in plants: a significant association in stress tolerance. Journal of Experimental Botany. 2020;71:6758-6774. DOI: 10.1093/jxb/eraa291

*Antioxidants - Benefits, Sources, Mechanisms of Action*

flavonoids and fungal colonisation in *Fagopyrum esculentum* and *F. tataricum*. Open Life Sciences. 2012;7:275-283. DOI:

2014;77:367-379. DOI: 10.1111/tpj.12388

[67] Valifard M, Mohsenzadeh S, Kholdebarin B. Salinity effects on phenolic content and antioxidant activity of Salvia macrosiphon. Iranian Journal of Science and Technology. Transactions A: Science. 2017;41:295- 300. DOI: 10.1007/s40995-016-0022-y

[68] Alqahtani A, Tongkao-on W, Li KM, Razmovski-Naumovski V, Chan K, Li GQ. Seasonal variation of triterpenes and phenolic compounds in Australian *Centella asiatica* (L.) Urb. Phytochemical Analysis. 2015;26:436-

443. DOI: 10.1002/pca.2578

[70] Kapoor D. Antioxidative defense responses and activation of phenolic compounds in *Brassica juncea* plants exposed to cadmium stress. International Journal of Green Pharmacy. 2016;10:228-234. DOI:

10.22377/IJGP.V10I04.760

plaphy.2010.08.016

[71] Gill SS, Tuteja N. Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants. Plant Physiology and Biochemistry. 2010;48: 909-930. DOI: 10.1016/j.

[72] Ahanger MA, Bhat JA, Siddiqui MH, Rinklebe J, Ahmad P. Integration of

[69] Michalak A. Phenolic compounds and their antioxidant activity in plants growing under heavy metal stress. Polish Journal of Environmental Studies. 2006;15: 523-530.

10.2478/s11535-012-0017-4

[66] Nakabayashi R, Yonekura-Sakakibara K, Urano K, Suzuki M, Yamada Y, Nishizawa T, Matsuda F, Kojima M, Sakakibara H, Shinozaki K, Michael AJ. Enhancement of oxidative and drought tolerance in Arabidopsis by overaccumulation of antioxidant flavonoids. The Plant Journal.

and environment. Journal of Cell and Molecular Biology. 2003;2:13-18

[58] Isah T. Stress and defense responses

production. Biological Research. 2019; 52: 39. DOI: 10.1186/s40659-019-0246-3

Ambwani TK, Ahmad AH, Rawat DS. Evaluation of phytochemicals in the leaf extract of Clitoria ternatea Willd. through GC-MS analysis. Tropical Plant Research. 2018;5:200-206. DOI:

Pieterse CM. The age of coumarins in plant–microbe interactions. Plant and Cell Physiology. 2019;60:1405-14019.

Rodríguez VM, Velasco P. Unraveling the metabolic response of Brassica oleracea exposed to Xanthomonas campestris pv. campestris. Journal of the Science of Food and Agriculture. 2018;98:3675-

in plant secondary metabolites

[59] Thakur AV, Ambwani S,

10.22271/tpr.2018.v5.i2.025

[60] Stringlis IA, De Jonge R,

DOI: 10.1093/pcp/pcz076

[61] Tortosa M, Cartea ME,

3683. DOI: 10.1002/jsfa.8876

Fregonara S, Bertuzzi T. Monitoring Phenolic Compounds in Rice during the Growing Season in Relation to Fungal and Mycotoxin Contamination. Toxins. 2020;12:341. DOI: 10.3390/

[63] Griffith M, Yaish MW. Antifreeze proteins in overwintering plants: a tale of two activities. Trends in Plant Science. 2004;9:399-405. DOI: 10.1016/j.

Szafrańska K, Janas KM, Corbineau F. Antioxidant enzymes and isoflavonoids in chilled soybean (*Glycine max* (L.) Merr.) seedlings. Journal of Plant Physiology. 2005;162:403-412. DOI:

[65] Regvar M, Bukovnik U, Likar M, Kreft I. UV-B radiation affects

[62] Giorni P, Rastelli S,

toxins12050341

tplants.2004.06.007

[64] Posmyk MM, Bailly C,

10.1016/j.jplph.2004.08.004

**560**

[73] Rodríguez-Calzada T, Qian M, Strid Å, Neugart S, Schreiner M, Torres-Pacheco I, Guevara-González RG. Effect of UV-B radiation on morphology, phenolic compound production, gene expression, and subsequent drought stress responses in chili pepper (*Capsicum annuum* L.). Plant Physiology and Biochemistry. 2019;134:94-102. DOI: 10.1016/j. plaphy.2018.06.025

[74] Caliskan O, Radusiene J, Temizel KE, Staunis Z, Cirak C, Kurt D, Odabas MS. The effects of salt and drought stress on phenolic accumulation in greenhouse-grown *Hypericum pruinatum*. Italian Journal of Agronomy. 2017;12. DOI: 10.4081/ija.2017.918.

[75] Martinez V, Mestre TC, Rubio F, Girones-Vilaplana A, Moreno DA, Mittler R, Rivero RM. Accumulation of Flavonols over Hydroxycinnamic acids favors oxidative damage protection under abiotic stress. Frontiers in Plant Science. 2016;7:838. DOI: 10.3389/fpls.2016.00838

[76] Król A, Amarowicz R, Weidner S. Changes in the composition of phenolic compounds and antioxidant properties of grapevine roots and leaves (*Vitis vinifera* L.) under continuous of longterm drought stress. Acta Physiologia Plantarum. 2014;36:1491-1499. DOI: 10.1007/s11738-014-1526-8.

[77] Alhanout K, Malesinki S, Vidal N, Peyrot V, Rolain JM, Brunel JM. New insights into the antibacterial mechanism of action of squalamine. Journal of Antimicrobial Chemotherapy. 2010;65:1688-1693. DOI: 10.1093/jac/ dkq213

[78] Pagare S, Bhatia M, Tripathi N, Pagare S, Bansal YK. Secondary

metabolites of plants and their role: Overview. Current Trends in Biotechnology and Pharmacy. 2015;9:293-304.

[79] Santolamazza-Carbone S, Sotelo T, Velasco P, Cartea ME. Antibiotic properties of the glucosinolates of Brassica oleracea var. acephala similarly affect generalist and specialist larvae of two lepidopteran pests. Journal of Pest Science. 2016;89:195-206. DOI: 10.1007/ s10340-015-0658-y

[80] Robin AH, Hossain MR, Park JI, Kim HR, Nou IS. Glucosinolate profiles in cabbage genotypes influence the preferential feeding of diamondback moth (*Plutella xylostella*). Frontiers in Plant Science. 2017;8:1244. DOI: 10.3389/fpls.2017.01244

[81] Jing-Yan WA, Zhao-Pu LI. Alkaloid accumulation in Catharanthus roseus increases with addition of seawater salts to the nutrient solution. Pedosphere. 2010;20:718-724. DOI: 10.1016/ S1002-0160(10)60062-8

[82] Kirk H, Vrieling K, Van Der Meijden E, Klinkhamer PG. Species by environment interactions affect pyrrolizidine alkaloid expression in Senecio jacobaea, Senecio aquaticus, and their hybrids. Journal of Chemical Ecology. 2010;36:378-387. DOI: 10.1007/ s10886-010-9772-8

[83] Yang L, Wen KS, Ruan X, Zhao YX, Wei F, Wang Q. Response of plant secondary metabolites to environmental factors. Molecules. 2018;23:762. DOI: 10.3390/molecules23040762

**563**

**Chapter 28**

**Abstract**

health benefits

**1. Introduction**

Valorization of Natural

Health Applications

*Cristina Rocha and José António Teixeira*

from natural sources, their nutritional and health potential.

Antioxidants for Nutritional and

*Pedro Ferreira-Santos, Zlatina Genisheva, Claudia Botelho,* 

The significant increase in the world population age, 47 years in 1950 to 73 years in 2020, resulted in an increase in aging related diseases as well as in degenerative diseases. In consequence, researchers have been focusing in the development of new therapies, with a particular emphasis on the use of compounds with antioxidant properties, namely phytochemicals, such as polyphenols and carotenoids. Several *in vitro* and *in vivo* studies have demonstrated the phytochemicals antioxidant capacity. Their use is broad, as they can be part of food supplements, medicine and cosmetics. The health benefit of antioxidant phytochemicals is an indisputable question. Phytochemical properties are highly influenced by the natural matrix as well as by extraction process, which have a key role. There are several extraction methods that can be applied depending on the chemical properties of the bioactive compounds. There is a wide range of solvents with different polarities, which allows a selective extraction of the desired target family of compounds. Greener technologies have the advantage to reduce extraction time and solvent quantity in comparison to the most traditional methods. This chapter will focus on the different green extraction strategies related to the recovery of antioxidant bioactive compounds

**Keywords:** bioactive compounds, antioxidants, green technologies, oxidative stress,

Nowadays, the awareness for the need to have a healthier lifestyle results in a higher consumption of natural organic food products and nutritionally rich antioxidants rather than synthetic and processed foods. In the past decade, an increased interest in the exploitation of natural ingredients to be used in the food and food products was observed. Researchers from all over the world are focusing on alternative sources of healthy nutrients promoting a safer and convenient diet. There is not clear evidence that synthetic antioxidants have toxic effects, although, consumer's interest is moving towards the natural products. Moreover, synthetic antioxidants and preservatives in food may lead to lipid peroxidation and deterioration of food flavor and quality [1]. Therefore, organic and sustainable processes, the identification of new phytochemicals with attractive biological activities, such as antioxidant,

## **Chapter 28**
