[1] Monoterpenes are derived biosynthetically from units of isopentenyl pyrophosphate, which is formed from acetyl-CoA via the intermediacy of mevalonic acid in the HMG-CoA reductase pathway.
Camphor, borneol, eucalyptol and ascaridole are examples of bicyclic monoterpenoids containing ketone, alcohol, ether, and bridging peroxide functional groups, respectively.
Several monoterpenes produced by trees, such as linalool, hinokitiol, and ocimene have fungicidal and antibacterial activities and participate in wound healing.
For example, sabinene contributes to the spicy taste of black pepper, 3-carene gives cannabis an earthy taste and smell, citral has a lemon-like pleasant odor and contributes to the distinctive smell of citrus fruits, and thujene and carvacrol are responsible for the pungent flavors of summer savory and oregano, respectively.
[12] For example, camphor, citral, citronellol, geraniol, grapefruit mercaptan, eucalyptol, ocimene, myrcene, limonene, linalool, menthol, camphene and pinenes are used in perfumes and cosmetic products.
[18][19] A study suggests that a range of floor cleaners with certain monoterpenes may cause indoor air pollution equivalent or exceeding the harm to respiratory tracts when the time is spent near a busy road.
[20][21] Another study suggests monoterpenes substantially affect ambient organic aerosol with uncertainties regarding environmental impacts.
"[24][better source needed] According to a review, several studies showed "that some monoterpenes (e.g., pulegone, menthofuran, camphor, and limonene) and sesquiterpenes (e.g., zederone, germacrone) exhibited liver toxicity" and that i.a.