4. Some biological activities of essential oils obtained in Colombia

EOs have been used in phytotherapy and folk medicine for their good odor and antibacterial, antifungal or insecticidal activities. Phenols, alcohols and aldehydes are EO components capable of crossing the cell wall, and in doing so, they alter its permeability and may cause leakage of macromolecules, loss of ions, structure disruption, and, eventually, cell death. This cytotoxicity enables EO applications against human pathogens or parasites and for the preservation of vegetal and marine products. Due to their large number of constituents, EOs affect several targets simultaneously, and this may be the reason for the lack of microorganism resistance development or adaptation. Besides cytotoxicity, the antioxidant properties of EOs are generally invoked as an indication of their potential benefits for human health. This is related to the notion that many diseases are due to high oxidative stress generated by diet, environmental contaminants, or work habits. However, the prooxidant properties of some EO components can play a protective role by promoting the removal of damaged cells. The mitochondria produce reactive oxygen species which can oxidize phenolic compounds (EO components) and give rise to reactive phenoxyl radicals which accelerate the general cell damage [72].

Genus Lippia (Verbenaceae family) has been the focus of attention of Colombian researchers (Figure 9). L. alba and L. origanoides EOs have appeared as the prominent representatives of this genus, after the evaluation of various Lippia genus EOs for antioxidant [33], antiviral [44], antimicrobial [69], antiprotozoal [71], and antigenotoxic [41, 42] activities.

Lippia origanoides Kunth (mountain oregano) is a good example of the aromatic plant biodiversity found in CENIVAM studies. It is an aromatic shrub found in the wild in northern South America and Central America. At least four different chemotypes have been distinguished according to differences in EO composition [34, 73]. Further research showed notorious differences in the compositions of the various chemotype extracts. Several uses of L. origanoides infusions in popular medicine have been related to antimicrobial and analgesic activities due to phenylpropanoids and flavonoids found among its secondary metabolites. The detection of thymol and carvacrol as main EO constituents and pinocembrin, naringenin, quercetin, and luteolin in mg/g amounts in extracts of various L. origanoides chemotypes supports the recognition of this species as a promising source of bioactive substances. L. origanoides is the second most studied species of the Lippia genus, preceded by L. alba. The useful bioactive properties found for L. origanoides oil have aroused interest in commercial applications such as food additive, preservative, or pest control agent, among others. L. origanoides oil is an important ingredient of various current chicken food commercial products. The most widely known sources of thymol and carvacrol are thyme (Thymus vulgaris) and oregano (Origanum vulgare), both of Eurasian origin. Thymol and carvacrol contents in thyme EO are in the range 37–55% and 0.5–5.5%, respectively (ISO 19817:2017). Oregano EO contains around 22% thymol and 18% carvacrol. Thymol and carvacrol are major components in three L. origanoides chemotypes. Several projects conducted in CENIVAM have related the variations in EO composition with the steam distillation conditions, with the phenological stage, the agricultural conditions, and the post-harvest treatment.

Compound

132

 family L. alba,

Carvone

Monoterpene

Oxygenated

Oxygenated

 compounds

(phenylpropanoids)

Sesquiterpene

Oxygenated

Table 1. Relative amounts of compound

 families in essential oils of various Lippia species grown in Colombia.

sesquiterpenes

0.3

 5.1

 1.1

—

0.4

—

5.2

 12.8

 0.5

 10.7

 0.2

 19.1

hydrocarbons

4.9

 11.9

 16.2

6.6

 5.3

 3.9

 29.1

 11.0

 3.2

 52.3

 5.3

 54.0

monoterpenes

hydrocarbons

31.5

61.4

—

6.9

 2.7

0.0

 63.3

 57.7

 2.0

 4.4

 47.7

 0.2

 78.1

 7..9

 62.4

 52.7

71.6

 2.1

 2.0

 7.4

 49.7

 2.8

 1.6

 2.0

 5.6

 4.1

 24.6

12.6

 14.7

 31.0

 45.7

 15.4

 44.9

 19.1

 12.2

 0.3

 Citral Citral + Carvone

 Myrcenone

 Thymol Carvacrol

Phellandrene

chemotypes

L.

origanoides,

chemotypes

L.

L.

L.

L.

L.

Essential Oils - Oils of Nature

citriodora

micromera

americana

graveolens

dulcis

Relative amount, %

felisis EOs. LC50 cytotoxicity values between 4.36–64.3 and 1.2–20.8 μg/mL, for 24 and 48 h exposure, respectively, were obtained. Most tested EOs can be considered

L. alba EOs of different origins in Colombia showed cytotoxicity in the Artemia franciscana assay at concentrations in the range from 7 to 21 μg/mL. The differences were attributed to compositional variations caused by the geographical habitat and

A study of 12 EOs of 7 Lippia species growing in Colombia employed GC-FID and GC-MS methods for their chemical characterization and the ORAC and ABTS assays for their antioxidant activity evaluation [76]. The ORAC and ABTS methods explore radical scavenging mechanisms in which the fundamental step is either the proton

transfer (ORAC) or the electron transfer (ABTS) [77]. The EOs with high phenylpropanoid content showed higher antioxidant capacity in both assays. The ORAC antioxidant activity of these oils was five or more times superior to those of butyl hydroxytoluene (BHT) and α-tocopherol, which are antioxidants used commonly in commercial products. This superiority was maintained, although at a smaller proportion, in the ABTS test. The ORAC and ABTS values measured individually for carvacrol and thymol were close to the values obtained for the EOs that

contain them as main components. For the remaining oils, not rich in

phenylpropanoids, there was no clear relationship between the oil's antioxidant activity and that of its main constituents (Table 2). The L. americana EO and the phellandrene-rich L. origanoides chemotype EO have mono- and sesquiterpene hydrocarbons as main components. They showed poor antioxidant activity under the ABTS assay conditions but did have higher antioxidant activity than BHT in the ORAC assay. This is consistent with the evaluation of individual unsaturated nonaromatic hydrocarbon terpenes (trans-ß-caryophyllene, α-phellandrene, ɣterpinene), which were capable of scavenging radicals by proton transfer (ORAC conditions) but were completely inactive under the ABTS assay conditions (electron transfer). All the 12 EOs examined, those of L. alba (carvone), L. alba (citral), L. alba (carvone+citral), L. alba (myrcenone), L. origanoides (carvacrol), L. origanoides (thymol), L. origanoides (phellandrene), L. citriodora, L. micromera, L. americana, L. graveolens, and L. dulcis exhibited higher antioxidant capacity than BHT and α-tocopherol in the ORAC assay, and this makes them very good candidates to become ingredients of final products in substitution of synthetic antioxidants.

EOs from plants of the Labiatae and Verbenaceae families are considered very useful in folk medicine, as antibacterials, antivirals, antifungals, antioxidants, and

A study of cytotoxic activity of EOs from the Verbenaceae and Asteraceae families included 36 species of various origins. These oils were tested on Jurkat, HeLa, HepG2, and Vero cell lines [75]. None of the tested EOs was cytotoxic, except that from Ambrosia arborescens, which showed IC50 of 16 3.4 μg/mL and was not active against the tested tumor cell lines. All the Verbenaceae family EOs examined produced dose-dependent inhibition on the growth of HeLa cells with determination coefficient R2 > 0.7. Four L. alba citral chemotype EOs and one oil of the L. alba, carvone chemotype, were active against HeLa cells. This activity was attributed to the presence of a target on HeLa that is not present on HepG2

cytotoxic (LC50 < 10 μg/mL), but bioactivity was highly dependent on EO

chemotype, extraction mode, and plant growing location.

DOI: http://dx.doi.org/10.5772/intechopen.87199

Study of Essential Oils Obtained from Tropical Plants Grown in Colombia

environmental factors (temperature, light intensity) [74].

and Jurkat cells.

4.2 Antioxidant activity

4.3 Antiviral activity

135

#### Figure 9.

Some tropical aromatic plants of Lippia genus (Verbenaceae family): L. origanoides, L. americana, L. micromera, and L. dulcis.

More than 30 botanical outings were organized by CENIVAM to various Colombian regions in the Andes, the Eastern Plains, the Caribbean, and the Pacific coasts. Over 1100 accessions of medicinal and aromatic plants were collected and taxonomically identified, under the due permit of access to the genetic resource. Hydro-distillation and steam distillation of these samples produced close to 1000 different EOs that were subjected to chemical characterization using GC techniques provided with FID and MS systems. Tests for antioxidant, antimicrobial, antiviral, antiparasitic, immunomodulatory, photoprotective, and antigenotoxic activities of the EOs revealed that more than 45% of these oils were highly active in one or two assays. The following sections highlight just a few of the interesting findings obtained in the search for natural ingredients with biological properties that may enable the development of products for the pharmaceutical, cosmetics, hygiene, or food industries.

#### 4.1 Cytotoxicity

Following the recognition of cytotoxicity and antioxidant capacity as main determinants of EO potential pharmaceutical applications, Olivero and co-workers [64] used the brine shrimp assay and the measurement of thiobarbituric acid induced in rat liver microsomes by a Fenton reagent to evaluate 13 EOs from Colombian plants for cytotoxicity and antioxidant capacity, respectively. Mean effective concentrations (EC50) below 100 μg/mL were registered for the Ocotea sp., Tagetes lucida, and L. alba (citral chemotype) EOs. Moderate values (130–174 μg/ mL) were obtained for the Elettaria cardamomum and L. alba (carvone chemotype, Tolima) EOs. No antioxidant activity (EC50 > 1 mg/mL) was found for the Minthostachys mollis, L. alba (carvone chemotype, Cundinamarca), and Piper sancti-

#### Study of Essential Oils Obtained from Tropical Plants Grown in Colombia DOI: http://dx.doi.org/10.5772/intechopen.87199

felisis EOs. LC50 cytotoxicity values between 4.36–64.3 and 1.2–20.8 μg/mL, for 24 and 48 h exposure, respectively, were obtained. Most tested EOs can be considered cytotoxic (LC50 < 10 μg/mL), but bioactivity was highly dependent on EO chemotype, extraction mode, and plant growing location.

L. alba EOs of different origins in Colombia showed cytotoxicity in the Artemia franciscana assay at concentrations in the range from 7 to 21 μg/mL. The differences were attributed to compositional variations caused by the geographical habitat and environmental factors (temperature, light intensity) [74].

A study of cytotoxic activity of EOs from the Verbenaceae and Asteraceae families included 36 species of various origins. These oils were tested on Jurkat, HeLa, HepG2, and Vero cell lines [75]. None of the tested EOs was cytotoxic, except that from Ambrosia arborescens, which showed IC50 of 16 3.4 μg/mL and was not active against the tested tumor cell lines. All the Verbenaceae family EOs examined produced dose-dependent inhibition on the growth of HeLa cells with determination coefficient R2 > 0.7. Four L. alba citral chemotype EOs and one oil of the L. alba, carvone chemotype, were active against HeLa cells. This activity was attributed to the presence of a target on HeLa that is not present on HepG2 and Jurkat cells.

#### 4.2 Antioxidant activity

A study of 12 EOs of 7 Lippia species growing in Colombia employed GC-FID and GC-MS methods for their chemical characterization and the ORAC and ABTS assays for their antioxidant activity evaluation [76]. The ORAC and ABTS methods explore radical scavenging mechanisms in which the fundamental step is either the proton transfer (ORAC) or the electron transfer (ABTS) [77]. The EOs with high phenylpropanoid content showed higher antioxidant capacity in both assays. The ORAC antioxidant activity of these oils was five or more times superior to those of butyl hydroxytoluene (BHT) and α-tocopherol, which are antioxidants used commonly in commercial products. This superiority was maintained, although at a smaller proportion, in the ABTS test. The ORAC and ABTS values measured individually for carvacrol and thymol were close to the values obtained for the EOs that contain them as main components. For the remaining oils, not rich in phenylpropanoids, there was no clear relationship between the oil's antioxidant activity and that of its main constituents (Table 2). The L. americana EO and the phellandrene-rich L. origanoides chemotype EO have mono- and sesquiterpene hydrocarbons as main components. They showed poor antioxidant activity under the ABTS assay conditions but did have higher antioxidant activity than BHT in the ORAC assay. This is consistent with the evaluation of individual unsaturated nonaromatic hydrocarbon terpenes (trans-ß-caryophyllene, α-phellandrene, ɣterpinene), which were capable of scavenging radicals by proton transfer (ORAC conditions) but were completely inactive under the ABTS assay conditions (electron transfer). All the 12 EOs examined, those of L. alba (carvone), L. alba (citral), L. alba (carvone+citral), L. alba (myrcenone), L. origanoides (carvacrol), L. origanoides (thymol), L. origanoides (phellandrene), L. citriodora, L. micromera, L. americana, L. graveolens, and L. dulcis exhibited higher antioxidant capacity than BHT and α-tocopherol in the ORAC assay, and this makes them very good candidates to become ingredients of final products in substitution of synthetic antioxidants.

#### 4.3 Antiviral activity

EOs from plants of the Labiatae and Verbenaceae families are considered very useful in folk medicine, as antibacterials, antivirals, antifungals, antioxidants, and

More than 30 botanical outings were organized by CENIVAM to various Colombian regions in the Andes, the Eastern Plains, the Caribbean, and the Pacific coasts. Over 1100 accessions of medicinal and aromatic plants were collected and taxonomically identified, under the due permit of access to the genetic resource. Hydro-distillation and steam distillation of these samples produced close to 1000 different EOs that were subjected to chemical characterization using GC techniques provided with FID and MS systems. Tests for antioxidant, antimicrobial, antiviral, antiparasitic, immunomodulatory, photoprotective, and antigenotoxic activities of the EOs revealed that more than 45% of these oils were highly active in one or two assays. The following sections highlight just a few of the interesting findings obtained in the search for natural ingredients with biological properties that may enable the development of products for the pharmaceutical, cosmetics, hygiene, or

Some tropical aromatic plants of Lippia genus (Verbenaceae family): L. origanoides, L. americana,

Following the recognition of cytotoxicity and antioxidant capacity as main determinants of EO potential pharmaceutical applications, Olivero and co-workers [64] used the brine shrimp assay and the measurement of thiobarbituric acid induced in rat liver microsomes by a Fenton reagent to evaluate 13 EOs from Colombian plants for cytotoxicity and antioxidant capacity, respectively. Mean effective concentrations (EC50) below 100 μg/mL were registered for the Ocotea sp., Tagetes lucida, and L. alba (citral chemotype) EOs. Moderate values (130–174 μg/ mL) were obtained for the Elettaria cardamomum and L. alba (carvone chemotype,

Tolima) EOs. No antioxidant activity (EC50 > 1 mg/mL) was found for the

Minthostachys mollis, L. alba (carvone chemotype, Cundinamarca), and Piper sancti-

food industries.

Figure 9.

L. micromera, and L. dulcis.

Essential Oils - Oils of Nature

4.1 Cytotoxicity

134


(100 <sup>μ</sup>g/mL). Ocimum campechianum EO showed relevant (1 <sup>10</sup><sup>3</sup>

Study of Essential Oils Obtained from Tropical Plants Grown in Colombia

DOI: http://dx.doi.org/10.5772/intechopen.87199

observed with L. alba, O. vulgare, and A. vulgaris oils at 100 μg/mL.

moderate anti-herpetic activity against HHV-1 and HHV-2, respectively.

) activity against HHV-1 and HHV-2 at concentrations of 100 and 50 μg/mL, respectively. Lepechinia salviifolia and Rosmarinus officinalis oils showed

The in vitro inhibitory effect of L. alba, L. origanoides, Origanum vulgare, and Artemisia vulgaris EOs on yellow fever virus was investigated by exposing African green monkey kidney (Vero) cells to EO prior to virus exposure [79]. None of the EOs studied was cytotoxic on these cells. The minimum concentration of the EO that inhibited virus titer by more than 50% (MIC) was determined by virus yield reduction assay. Preincubation of virus with selected EO for 24 h at 4°C before adsorption on Vero cell inhibited the subsequent extracellular virus titer. Vero cells were exposed to EO 24 h at 37 °C before the adsorption of untreated virus. The presence of EO in the culture medium enhanced the antiviral effect: L. origanoides oil at 11.1 μg/mL produced a 100% reduction of virus yield, and the same result was

Since plants are exposed daily to the sun radiation, they have evolved mechanisms that protect them from the effects of overexposure, such as damages to the DNA. When DNA suffers a damage, the cell responds with a set of actions that was discovered in 1975 by Miroslav Radman [80], who assigned the name of SOS response. The Pasteur Institute developed a colorimetric assay to detect carcinogens, based on this response in which the exposition to UV causes the DNA damage whose extent is associated with the intensity of light absorbance by a chromophore [81]. This SOS chromotest is highly sensitive to UV. A modified version has been used by Fuentes and collaborators [82] to identify plants of Colombian flora that may be a source of genoprotective compounds. Their application of the SOS

chromotest in a survey of 50 extracts obtained with supercritical CO2 from aromatic plants grown in Colombia permitted to identify those that significantly reduced UV-induced genotoxicity depending on their concentration, as follows: Baccharis nitida, Solanum crotonifolium, Hyptis suaveolens, Persea caerulea, and L. origanoides. Volatile secondary metabolites have been the subject of antigenotoxicity tests. L. alba, L. micromera and L. origanoides EOs were found antigenotoxic, and the evaluation of their main constituents showed that carvacrol, thymol, citral, p-cymene, and geraniol inhibited the UV-induced genotoxicity in the

Synthetic insecticides are the most frequent pest control method in crop production and storage. However, their application has negative effects on environmental resources, elimination of beneficial insects, and toxicity for susceptible species and humans, who represent the last link in the food chain. EOs have attracted attention in recent years as potential pest control agents due to their insecticidal, repellent, and/or antifeedant properties. Stored products of insect pest

control are important in managing post-harvest grains, food products and

(0.00002, 0.0002, 0.002, 0.02, and 0.2 μL/cm<sup>2</sup>

processed goods. Tribolium castaneum (Herbst) is one of the most common insect pests worldwide of flourmills, grocery shops and warehouses. Jaramillo et al. [84] examined the repellent effect of Colombian Croton malambo (Karst) EO against T. castaneum using the area preference method. A filter paper was divided in halves. On one half, equal volumes of different concentrations of EO dissolved in acetone

) and the other with acetone only as

(1 <sup>10</sup><sup>1</sup>

4.4 Antigenotoxicity

SOS chromotest [83].

4.5 Repellence

137

) and mild

#### Table 2.

Main constituents and antioxidant capacity of Lippia essential oils.

insecticides. The antiviral activity of 40 EOs of the Labiatae and Verbenaceae families and some monoterpenes were evaluated on human herpes virus types 1 and 2 using the end point titration technique [78]. Samples that showed reduction factor of viral titer in comparison to control without treatment (Rf) at least against one viral type, at concentrations lower than or equal to 100 μg/mL, were considered active. Hyptis mutabilis oil showed a high activity against both viruses (HHV-1 and HHV-2), with Rf values of 10<sup>3</sup> and 10<sup>2</sup> , respectively, at a concentration of 50 μg/mL. Lepechinia vulcanicola and Mintostachys mollis EOs showed the same reduction factor of viral titer against both viral types at a concentration of 100 μg/mL. Lepechinia salviifolia was moderately active against both viruses at the same concentration

Study of Essential Oils Obtained from Tropical Plants Grown in Colombia DOI: http://dx.doi.org/10.5772/intechopen.87199

(100 <sup>μ</sup>g/mL). Ocimum campechianum EO showed relevant (1 <sup>10</sup><sup>3</sup> ) and mild (1 <sup>10</sup><sup>1</sup> ) activity against HHV-1 and HHV-2 at concentrations of 100 and 50 μg/mL, respectively. Lepechinia salviifolia and Rosmarinus officinalis oils showed moderate anti-herpetic activity against HHV-1 and HHV-2, respectively.

The in vitro inhibitory effect of L. alba, L. origanoides, Origanum vulgare, and Artemisia vulgaris EOs on yellow fever virus was investigated by exposing African green monkey kidney (Vero) cells to EO prior to virus exposure [79]. None of the EOs studied was cytotoxic on these cells. The minimum concentration of the EO that inhibited virus titer by more than 50% (MIC) was determined by virus yield reduction assay. Preincubation of virus with selected EO for 24 h at 4°C before adsorption on Vero cell inhibited the subsequent extracellular virus titer. Vero cells were exposed to EO 24 h at 37 °C before the adsorption of untreated virus. The presence of EO in the culture medium enhanced the antiviral effect: L. origanoides oil at 11.1 μg/mL produced a 100% reduction of virus yield, and the same result was observed with L. alba, O. vulgare, and A. vulgaris oils at 100 μg/mL.

#### 4.4 Antigenotoxicity

Since plants are exposed daily to the sun radiation, they have evolved mechanisms that protect them from the effects of overexposure, such as damages to the DNA. When DNA suffers a damage, the cell responds with a set of actions that was discovered in 1975 by Miroslav Radman [80], who assigned the name of SOS response. The Pasteur Institute developed a colorimetric assay to detect carcinogens, based on this response in which the exposition to UV causes the DNA damage whose extent is associated with the intensity of light absorbance by a chromophore [81]. This SOS chromotest is highly sensitive to UV. A modified version has been used by Fuentes and collaborators [82] to identify plants of Colombian flora that may be a source of genoprotective compounds. Their application of the SOS chromotest in a survey of 50 extracts obtained with supercritical CO2 from aromatic plants grown in Colombia permitted to identify those that significantly reduced UV-induced genotoxicity depending on their concentration, as follows: Baccharis nitida, Solanum crotonifolium, Hyptis suaveolens, Persea caerulea, and L. origanoides. Volatile secondary metabolites have been the subject of antigenotoxicity tests. L. alba, L. micromera and L. origanoides EOs were found antigenotoxic, and the evaluation of their main constituents showed that carvacrol, thymol, citral, p-cymene, and geraniol inhibited the UV-induced genotoxicity in the SOS chromotest [83].

#### 4.5 Repellence

Synthetic insecticides are the most frequent pest control method in crop production and storage. However, their application has negative effects on environmental resources, elimination of beneficial insects, and toxicity for susceptible species and humans, who represent the last link in the food chain. EOs have attracted attention in recent years as potential pest control agents due to their insecticidal, repellent, and/or antifeedant properties. Stored products of insect pest control are important in managing post-harvest grains, food products and processed goods. Tribolium castaneum (Herbst) is one of the most common insect pests worldwide of flourmills, grocery shops and warehouses. Jaramillo et al. [84] examined the repellent effect of Colombian Croton malambo (Karst) EO against T. castaneum using the area preference method. A filter paper was divided in halves. On one half, equal volumes of different concentrations of EO dissolved in acetone (0.00002, 0.0002, 0.002, 0.02, and 0.2 μL/cm<sup>2</sup> ) and the other with acetone only as

insecticides. The antiviral activity of 40 EOs of the Labiatae and Verbenaceae families and some monoterpenes were evaluated on human herpes virus types 1 and 2 using the end point titration technique [78]. Samples that showed reduction factor of viral titer in comparison to control without treatment (Rf) at least against one viral type, at concentrations lower than or equal to 100 μg/mL, were considered active. Hyptis mutabilis oil showed a high activity against both viruses (HHV-1 and

Main compounds Yield,

α-terpinene (3.0%), thymol (64 6%), carvacrol (12 2%), trans-βcaryophyllene (2.9%)

(5.0%), neral (15.6%), geranial (18.9%), spathulenol (4.7%)

p-Cymene (12%), carvacrol (46.2%), γ-terpinene (9.6%)

γ-Terpinene (5.0%), thymol (54.5%), thymyl acetate (4.8%)

p-Cymene (11.2%), limonene (7.2%), trans-β-caryophyllene (11.3%), αphellandrene (9.9%)

thymyl methyl ether (14.9%)

(6.0%)

caryophyllene (12.2%), germacrene D (16.3%)

L. alba (carvona) Limonene (30.2%), carvone (50.3%) 0.8 1340 54 126.4 0.7

Carvacrol 3410 50 4609 6 Thymol 3000 103 5700 125

γ-Terpinene 1766 8 N.D. α-Phellandrene 1040 18 136 3 α-Tocopherol 550 13 2429 7 BHT 457 9 4760 23 1,8-Cineole 299 5 N.D. p-Cymene 219 2 N.D.

L. graveolens 6-Methyl-5-hepten-2-one (4.9%),

L. citriodora Limonene (10.7%), 1,8-cineole

L. micromera p-Cymene (13.1%), thymol (29.1%),

L. alba (citral) Geranial (27%), neral (21%), geraniol

Main constituents and antioxidant capacity of Lippia essential oils.

L. americana Sabinene (7.4%), trans-β-

% w/w

Lepechinia vulcanicola and Mintostachys mollis EOs showed the same reduction factor of viral titer against both viral types at a concentration of 100 μg/mL. Lepechinia salviifolia was moderately active against both viruses at the same concentration

, respectively, at a concentration of 50 μg/mL.

Essay ( s, n = 3)

ABTS (μmol Trolox®/g compound)

ORAC (μmol Trolox®/g compound)

1.2 3990 58 5410 48

0.1 3630 40 41 2

4.4 3400 120 5200 109

3.1 2840 72 5090 42

1.5 1820 82 310 2

1.0 2050 78 2750 80

0.9 2000 77 24.8 0.4

0.5 1200 27 239 4

2800 109 N.D.

HHV-2), with Rf values of 10<sup>3</sup> and 10<sup>2</sup>

Essential oil (chemotype) or standard compound

Essential Oils - Oils of Nature

L. origanoides (carvacrol)

L. origanoides (thymol)

L. origanoides (phellandrene)

Trans-βcaryophyllene

Table 2.

136

control. These halves were joined, and a fixed number of insects were released on the center. Observations on the number of insects present on both the treated and untreated halves were recorded after 2 and after 4 h. The highest repellent activity was observed at an EO concentration of 0.2 μL/cm<sup>2</sup> . Repellence values of 86% 5 (2 h) and 92% 3 (4 h) were observed, which were higher than those obtained for a commercial repellent at the same concentration and exposure times (78% 5 and 76% 9, respectively).

FP44842-212-2018, is gratefully acknowledged. The authors thank Ministerio de Ambiente y Desarrollo Sostenible, through its Dirección de Bosques, Biodiversidad y Servicios Ecosistémicos for their permission of access to genetic resources, and derived products for the program ran by the Unión Temporal Bio-Red-CO-

The authors declare that they do not have conflict of interest.

Study of Essential Oils Obtained from Tropical Plants Grown in Colombia

CENIVAM (Resolution 0812, June 4, 2014).

DOI: http://dx.doi.org/10.5772/intechopen.87199

Conflict of interest

Author details

139

Elena Stashenko\* and Jairo René Martínez

provided the original work is properly cited.

\*Address all correspondence to: elena@tucan.uis.edu.co

Santander, Bucaramanga, Colombia

Research Center for Biomolecules, CENIVAM, Universidad Industrial de

© 2019 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,

Weevils that consume flour (Tribolium castaneum), peanuts and wheat bread (Ulomoides dermestoides) merit attention alongside other insects of major concern in crop production and storage of cereals and other products. Alcala and co-workers [85] used the area preference method to show that EOs of Elettaria cardamomum, Salvia officinalis and L. origanoides (carvacrol chemotype) had repellent action against both pest insects, while the repellency in the controls was null. This repellency increased when the EO concentrations were higher. None of the EOs presented attractant action for either of the exposure times. A 100% repellency was obtained at the highest concentration tested (1.6% v/v), except for S. officinalis against U. dermestoides at 2 h of treatment that had a 97% of repellency. Mean repellent concentration (RC50) values showed that E. cardamomum, S. officinalis, and L. origanoides had better repellent properties against U. dermestoides than a commercial preparation that contained 15% of ethyl butylacetylaminopropionate. The carvacrol-rich chemotype of L. origanoides was the most potent, with RC50 values of 0.220 and 0.207% (v/v), for T. castaneum and U. dermestoides, respectively.

Several tropical diseases for which there is no vaccine yet (yellow fever, Zika fever, chikungunya, dengue) are transmitted by Aedes aegypti. The strategies to prevent these illnesses involve the use of insecticide or repellent agents. Since several pesticides have deleterious environmental effects and affect humans, there is a strong interest in finding EOs and plant extracts that can be effective in controlling Aedes aegypti. The guideline that good larvicide candidates are substances with LC50 < 100 mg/L [86] shows the importance of the finding that the EOs from L. origanoides (LC50 = 54 mg/L) and Swinglea glutinosa (LC50 = 66 mg/L) had an improved performance when used as a mixture (LC50 = 38 mg/L). Other EO binary mixtures showed similarly interesting activity (Turnera diffusa and S. glutinosa, LC50 = 64 mg/L; L. alba and S. glutinosa, LC50 = 49 mg/L) [87].
