MOLECULE

α-trans-bergamotene

α-Trans-bergamotene belongs to the class of organic compounds known as bicyclic sesquiterpenoids. These are sesquiterpenoids containing exactly two rings, which are fused together. α-Trans-bergamotene is formally classified as a polycyclic hydrocarbon although it is biochemically a sesquiterpene as it synthesized via multiple isoprene units. Sesquiterpenes are terpenes that contain 15 carbon atoms and are comprised of three isoprene units. The biosynthesis of sesquiterpenes is known to occur mainly through the mevalonic acid pathway (MVA), in the cytosol. However, recent studies have found evidence of pathway crosstalk with the methyl-erythritol-phosphate (MEP) pathway in the cytosol. Farnesyl diphosphate (FPP) is a key intermediate in the biosynthesis of cyclic sesquiterpenes. FPP undergoes several cyclization reactions to yield a diverse number of cyclic arrangements. There are four known Bergamotene isomers including α-cis-, α-trans-, β-cis- and β-trans-bergamotene. α-trans-bergamotene is a neutral, hydrophobic molecule that is insoluble in water. It exists as a clear, greenish oil that has a woody or warm tea-like odor. It is found in the fruits and essential oils of anise, basil, cumin, carrot, bergamot, lime, lemon, cottonseed, nutmeg, black pepper and kumquat. α-trans-bergamotene is also found in the essential oils of plants such as tobacco (PMID:28434859) and cannabis (PMID:6991645). It is also a constituent of cannabis smoke and is volatilized during the combustion of cannabis (https://doi.org/10.1007/978-1-59259-947-9_2). Isomers of bergamotene have a function as pheromones for some insect species. Evidence suggests that plants under attack by herbivore insects are able to release specific amounts of bergamotene to attract natural enemies of the insect herbivores, using these sesquiterpenes as a defense mechanism (PMID: 16418295). More specifically, the tobacco plant emits α-trans-bergamotene from its flowers at night to attract the tobacco hawk moth (Manduca sexta) as a pollinator; however, during the day the leaves produce α-trans-bergamotene to lure predatory insects to feed on any larvae and eggs that the pollinator may have produced (PMID: 28434859).