**3. Plants with terpenoids**

Terpenoids, or isoprenoids, are isoprene-based compounds with major jobs in the digestion of all living beings [27]. Varieties of terpenoids are particularly high in plants where many can be viewed as secondary metabolites. Such specific plant terpenoids underlie numerous natural co-operations between plants, creatures, and microorganisms (**Tables 1–4**) [38], going about as allele-synthetics to repulse herbivores, tempt pollinators, or allure herbivore hunters [39]. The development of terpenoids in plants started with the enrollment of genes from primary metabolism and sped up because of the multiplication of cytochrome P450 and terpene synthase gene families in the genomes of plants [40].


#### **Table 1.**

*List of some plants contains terpenes and terpenoids [28–31].*


#### **Table 2.**

*List of some animals contains terpenes and terpenoids [31–33].*


#### **Table 3.**

*List of some fungi contains terpenes and terpenoids [34, 35].*


#### **Table 4.**

*List of some bacteria contains terpenes and terpenoids [36, 37].*

Terpenoid compounds partly mirrors a characteristic history set apart by herbivory stress and other particular tensions forced by creatures, bringing about a wide cluster of functionalized terpenoids in the plant realm pre-chosen for their strong organic activities towards animals [41]. This specific cycle might have been brought about by the overall closeness of protein structures and amino acid sequence among

plant and creature proteins, bringing about planting auxiliary metabolites with a natural resemblance for creature proteins by ethicalness of having been delivered by plant bio-catalyst made out of similar amino acids [32].

Terpenoids are dependent on the tetracyclic 6–6–6-5 lanostane carbon skeleton structure a subsection of the terpenome known as the sterolome. The sterolome is assessed to contain about 1000 biogenic derivatives obtained from lanosterol and related particles that do fundamental organic functions across all areas of life on Earth [42].

Many plant terpenoids have been tracked down coincidentally uses in medication and the terpenoids family has been an important wellspring of clinical revelations. However, the testing system is meticulous and asset concentrated. The genuine number of plants terpenoids in nature that might be evaluated for therapeutic applications is obscure however is possibly more than 105, including more than 12,000 from the diterpenoid specifically [43]. While this number is little contrasted with current combinatorial techniques, the lead compound disclosure rate might be altogether higher for plant-based compounds. It is due to a crucial role in chemical, and metabolic processes, many are produced in limited quantities, only in response to a stimulus, or amass solely in particular tissues, requiring microbial multiplication or significant advances by plant rearing and hereditary improvement to get adequate amounts to research clinical benefits [44, 45].

## **4. Medicinal importance**

Terpenoids have an expansive group of clinical activities (**Figure 8**) and are spread everywhere, they have been utilized in conventional medications for ancient times. Numerous compounds can be found commercially, majorly as dietary enhancements; nonetheless, some of them are enrolled as medications.

#### **4.1 Anti- insect activity**

Human wellbeing and crop cultivation are mainly affected by insects, and trying to control these bugs the application of chemical bug sprays has become broad. Notwithstanding, this has brought about the improvement of obstruction in these living creatures, human infections, tainting of food, and contamination of the climate. Herbs and medicinal oils like terpenes and terpenoids have been displayed to have a huge potential for bug control like carvacrol, limonene, linalool, 1, 8 cineole, eugenol, and β-ionone; especially against three insects namely lice, cockroaches, and Triatominae bugs [46–48].

#### **4.2 Anti-microbial activity**

Antimicrobial properties or the capacity to kill or stop the development of a microorganism in terpenes are normally utilized in customary and current day medication. The accompanying plants produce terpenes that have antimicrobial potential: Pinusponderosa (Pinaceae), flavors (cumin, rosemary, thyme, caraway, clove, and sage), Cretan propolis, Helichrysumitalicum, Rosmarinus officinalis, etc. [49].

There are 52 anti-microbial terpenoids, including hydrocarbons of the oil; aromadendrene (4.4%), limonene (3.8%), α-cedrene (9.6%), β-caryophyllene (4.2%), and α-pinene (10.2%), geranyl acetic acid derivation (4.7%), 2-methylcyclohexyl

*Revisiting the Medicinal Value of Terpenes and Terpenoids DOI: http://dx.doi.org/10.5772/intechopen.102612*

**Figure 8.** *Reported and traditional therapeutic application of terpenes and terpenoids.*

pentanoate (8.3%), 2-methylcyclohexyl octanoate (4.8%), and neryl acetic acid derivation (11.5%) etc. [50, 51].

### **4.3 Anti- plasmodial activity**

Terpenes have been shown to have a favorable anti-plasmodial activity. With the rising malarial infections and drug resistance, terpenes have gained more attention towards it through anti-plasmodial activity. Terpenes have been shown to have a favorable anti-plasmodial activity. With the rising malarial infections and drug resistance, terpenes have gained more attention towards it through anti-plasmodial activity. Different kinds of terpenes show different effects on the parasites. The most common terpenes with anti-plasmodial potential are Beta-myrcene limonene, pinene, caryophyllene, etc. Thus, terpenes could be a safer and a cost-effective alternative for malarial treatment [52, 53].

#### **4.4 Anti-cancer activity**

Cancer-related observational studies propose that dietary monoterpenes might be useful in the anticipation and treatment of malignant growths. Among dietary monoterpenes, D-limonene and perillyl alcohol have been displayed to have chemopreventive and health beneficial properties against numerous human malignant growths. At present they are professed to inhibit fraction-dependent proliferation of skin, lung, mammary, liver, colon, prostate, pancreatic, and stomach carcinomas [54, 55].

### **4.5 Anti-viral activity**

Presently, the antiviral potential of terpenoids is somewhat ineffectively perceived. Consequently, there is a ton of exploration pointed towards finding agents, likewise from natural sources, which could have intense antiviral potential. The new antiviral compounds ought to explicitly restrain the virus and ought not to affect the healthy biological environment of the cell. The quest for natural antiviral moieties has paved the way for the extraction of isoborneol. Potent anti- herpes simplex virus −1 (anti-HSV-1) activities have also been reported for monoterpenes such as cineol and borneol [56, 57].

#### **4.6 Anti-hyperglycemic activity**

Type 2 diabetes mellitus is a chronic metabolic disorder that results from reduced first-phase insulin secretion. Stevioside is a diterpene steviol glycoside extracted from leaves of the plant Stevia rebaudiana, which possesses insulinotropic, glucagonostatic, and anti-hyperglycemic effects [58, 59].

#### **4.7 Anti-inflammatory activity**

(−)-linalool, a naturally occurring enantiomer, possesses anti-inflammatory activity. Moreover, (−)-linalool and its ester, linalyl acetate, demonstrated analgesic and edema reducing effects [60–62].

#### **4.8 Anti-malarial activity**

Artemisinin (sesquiterpene lactone) is secluded from *Artemisia annua* Linn. It is the best antimalarial drug after pyrimethamine, chloroquine, and primaquine, and has the attributes of a high therapeutic index. Afterward, antimalarial medications, for example, artesunate, arteether, and artemether have been isolated by altering the chemistry of artemisinin. Nirolidol likewise has ant-malarial activity [63, 64].

#### **4.9 Cardio-protective activity**

Finding a powerful boon for treating the cardiovascular problems is a pressing objective for researchers. Tanshinone IIA (TS) is a functioning moiety separated from the rhizome of Chinese home-grown medication *Salvia miltiorrhiza Bunge*. The most recent discoveries recommend that TS can forestall the emergence of atherosclerosis and the harm and hypertrophy of the heart [65, 66].

### **4.10 Anti-tubercular activity**

Tuberculosis is a very fatal disease to mankind and still the treatment regimen and new drug discovery attract the researchers to reveal a new paradigm in medical science. For the first time, diterpenoid of isosteviol, its binuclear derivatives, tri-terpenoid betulinic, oleanolic, and ursolic acids have been reported to possess anti-tubercular activity, manifested by the molecular docking method. Other natural constituents of the class are Geranylgeraniol, phytanol, escobarine A, escobarine B, furanoditerpenes, salasol A, germacrane, alantolactone, etc. [67, 68].
