# Biochemistry of Terpenes and Recent Advances in Plant Protection
## 4 Other Applications of Terpenes  
Apart from the role of plant protection, terpenes also offer a wide range of prospects in the pharmaceutical, food, cosmetic, and flavoring industries. In the petrochemical industries, volatile terpen are being explored as emerging alternatives for energy production. Leveraging plant-derived terpenes as an alternative energy source is a sustainable way of alleviating the over-dependence on fossil fuels and their accompanying adverse impact on atmospheric CO\({}_{2}\) and climate change [146]. [PERSON] et al. reported that terpenes could be a fuel source in isolation or a blend of 65% in gasoline or diesel machines. [PERSON] et al. also suggested that hydrogenated valencene, premnaspirodiene, and caryophyllene could be used to generate high-density fuels using heterogeneous acid catalysts, Nafion SAC-13 [147; 148; 149]. Terpenes are used as flavoring and fragrance compounds in the food and toiletties industries, contributing over 5.3 billion USD annually in the United States, with a 3.7% increase in annual demand [150]. For example, (-)-Menthol (1-menthol) extracted from _Mentha arensis_ (Wild mint) is a flavoring ingredient in pharmaceuticals, cigarettes, cosme, chewing gums, and toothpaste manufacturing [150; 151]. Menthone and its stereoisomers (menthone and isomenthone), extracted from _Pelargonium geranium_, are added to beverages to enhance their cooling, misty, and sweet scent (Geraniums) [152]. The flavor and fragrant properties of linalool make it a valuable ingredient in food and drinks, perfumes, and cosmetic products [150]. Isoprenol resources remain unexhausted natural products, as many research investigations are still unearthing their beneficial values as antidotes to human problems. There has been a consistent molecular and pharmacological analysis of terpenes for potential anti-inflammatory, anti-tumor, anti-oxidative, antiaggregatory, and anti-coagulative effects. Some terpen exhibited highly extreme activity against malaria and cancer. For example, the anticancer property of Taxol(r), a drug obtained from diterpenoids, and artemisinin obtained from a sesquiterpene, lactone, are among the vital pharmacological products from terpen that are still effective to date. Terpenes confer anticancer activity by inducing apoptosis or necrosis to inhibit tumor cell proliferation in isolation or a blend with chemotherapy substances, e.g., \(\beta\)-Caryophyllene Eugenol, Menthol, limonene, and Ingenol 3-angelate (the diterpene), among others [153; 154; 32]. Despite the massive application of terpenes, a few factors, however, impede the realization of their full potential as the much-desired alternatives to synthetic compounds. The commercial quantity of natural plant-derived terpenes is minute and primarily does not meet commercial quantities. Microbes remain an excellent alternative as bio-factories for their engineering. However, the higher titers of some terpen pose another survival limitation for the microbes. That notwithstanding, the prospects of sophisticated omic \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Name of Terpene** & **Plant** & **Activity** & **Reference** \\ \hline Momilactone A & _Oryza sativa, Arabidopsis_, alfalfa, lettuce, cress, timothy, barnyard grass, _E. colomum_, crabgrass & Momilactones are generally not toxic to rice plants but mainly inhibit germination and growth of other seeds, e.g., barnyard grass Enhances plants to outcompete other field crops by roots exudates serving as inhabitants, especially Momilactones A and B & [140; 141; 142] \\ \hline Comilactone E & & _Amarantlus retroflexu, Sinapis_ & Exhibits high inhibition against common weeds at a lower concentration & [143] \\ \hline Limonene and (+)-citronellal & Transgenic _Arabidopsis thaliana_ & Exhibits vigorous antimicrotubule activity in transgenic _Arabidopsis thaliana_ & [144] \\ \hline Lanast-7,9(11)-dien-3\(\alpha\), 15\(\alpha\)-diol-3\(\alpha\)-D-glucofuranoside & _Oryza sativa_ & Growth inhibition & [145] \\ \hline \hline \end{tabular}
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