The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes", terpenoids contain additional functional groups, usually containing oxygen. When combined with the hydrocarbon terpenes, terpenoids comprise about 80,000 compounds. They are the largest class of plant secondary metabolites, representing about 60% of known natural products. Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists.
Terpenes are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. In plants, terpenes and terpenoids are important mediators of ecological interactions, while some insects use some terpenes as a form of defense. Other functions of terpenoids include cell growth modulation and plant elongation, light harvesting and photoprotection, and membrane permeability and fluidity control.
Diterpenes are a class of terpenes composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primary intermediate. Diterpenes form the basis for biologically important compounds such as retinol, retinal, and phytol. They are known to be antimicrobial and anti-inflammatory.
Citral is an acyclic monoterpene aldehyde. Being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the E-isomer is named geranial or citral A. The Z-isomer is named neral or citral B. These stereoisomers occur as a mixture, not necessarily racemic; e.g. in essential oil of Australian ginger, the neral to geranial ratio is 0.61.
Rose oil is the essential oil extracted from the petals of various types of rose. Rose ottos are extracted through steam distillation, while rose absolutes are obtained through solvent extraction, the absolute being used more commonly in perfumery. The production technique originated in Greater Iran. Even with their high price and the advent of organic synthesis, rose oils are still perhaps the most widely used essential oil in perfumery.
Vachellia farnesiana, also known as Acacia farnesiana, and previously Mimosa farnesiana, commonly known as sweet acacia, huisache, or needle bush, is a species of shrub or small tree in the legume family, Fabaceae. Its flowers are used in the perfume industry.
Humulene, also known as α-humulene or α-caryophyllene, is a naturally occurring monocyclic sesquiterpene (C15H24), containing an 11-membered ring and consisting of 3 isoprene units containing three nonconjugated C=C double bonds, two of them being triply substituted and one being doubly substituted. It was first found in the essential oils of Humulus lupulus (hops), from which it derives its name. Humulene is an isomer of β-caryophyllene, and the two are often found together as a mixture in many aromatic plants.
Nerolidol, also known as peruviol and penetrol, is a naturally occurring sesquiterpene alcohol. A colorless liquid, it is found in the essential oils of many types of plants and flowers. There are four isomers of nerolidol', which differ in the geometry about the central double bond and configuration of the hydroxyl-bearing carbon, but most applications use such a mixture. The aroma of nerolidol is woody and reminiscent of fresh bark. It is used as a flavoring agent and in perfumery as well as in non-cosmetic products such as detergents and cleansers. Nerolidyl derivatives include nerolidyl diphosphate and the fragrance nerolidyl acetate.
Zingiberene is a monocyclic sesquiterpene that is the predominant constituent of the oil of ginger, from which it gets its name. It can contribute up to 30% of the essential oils in ginger rhizomes. This is the compound that gives ginger its distinct flavoring.
Perillaldehyde, perillic aldehyde or perilla aldehyde, is a natural organic compound found most abundantly in the annual herb perilla, but also in a wide variety of other plants and essential oils. It is a monoterpenoid containing an aldehyde functional group.
Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modifications such as oxidation or rearrangement produce the related sesquiterpenoids. A recent study conducted in the Cosmics Leaving Outdoor Droplets large cloud chamber at CERN, has identified sesquiterpenes—gaseous hydrocarbons that are released by plants—as potentially playing a major role in cloud formation in relatively pristine regions of the atmosphere.
Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen functionality or missing a methyl group, are called monoterpenoids. Monoterpenes and monoterpenoids are diverse. They have relevance to the pharmaceutical, cosmetic, agricultural, and food industries.
Cannabis flower essential oil, also known as hemp essential oil, is an essential oil obtained by steam distillation from the flowers, panicles, stem, and upper leaves of the hemp plant. Hemp essential oil is distinct from hemp seed oil and hash oil: the former is a vegetable oil that is cold-pressed from the seeds of low-THC varieties of hemp, the latter is a THC-rich extract of dried female hemp flowers (marijuana) or resin (hashish).
Phenethyl alcohol, or 2-phenylethanol, is an organic compound with the chemical formula C6H5CH2CH2OH. It is a colourless liquid with a pleasant floral odor. It occurs widely in nature, being found in a variety of essential oils. It is slightly soluble in water, but miscible with most organic solvents. The molecule of phenethyl alcohol consists of a phenethyl group attached to a hydroxyl group.
Undecylenic acid is an organic compound with the formula CH2=CH(CH2)8CO2H. It is an unsaturated fatty acid. It is a colorless oil. Undecylenic acid is mainly used for the production of Nylon-11 and in the treatment of fungal infections of the skin, but it is also a precursor in the manufacture of many pharmaceuticals, personal hygiene products, cosmetics, and perfumes. Salts and esters of undecylenic acid are known as undecylenates.
The enzyme aristolochene synthase catalyzes the chemical reaction
Absinthin is a naturally produced triterpene lactone from the plant Artemisia absinthium (Wormwood). It constitutes one of the most bitter chemical agents responsible for absinthe's distinct taste. The compound shows biological activity and has shown promise as an anti-inflammatory agent, and should not be confused with thujone, a neurotoxin also found in Artemisia absinthium.
Juvabione, historically known as the paper factor, is the methyl ester of todomatuic acid. Both are sesquiterpenes (C15) found in the wood of true firs of the genus Abies. They occur naturally as part of a mixture of sesquiterpenes based upon the bisabolane scaffold. Sesquiterpenes of this family are known as insect juvenile hormone analogues (IJHA) because of their ability to mimic juvenile activity in order to stifle insect reproduction and growth. These compounds play important roles in conifers as the second line of defense against insect induced trauma and fungal pathogens.
Bisabolenes are a group of closely related natural chemical compounds which are classified as sesquiterpenes. Bisabolenes are produced from farnesyl pyrophosphate (FPP) and are present in the essential oils of bisabol, and of a wide variety of other plants including cubeb, lemon, and oregano. Various derivates also function as pheromones in different insects, such as stink bugs and fruit flies. Bisabolenes are produced by several fungi, though their biological role in that group of organisms remains unclear.
Avarol is a hydroquinone first isolated from the Mediterranean marine sponge Dysidea avara 1974 Avarol represented the first sesquiterpenoid with a rearranged drimane skeleton and its structure was established by standard analytical methods, chemical degradation and later by stereocontrolled synthesis. Intrigued by the wide range of biological activities of this metabolite, Avarol has inspired the development of many synthetic derivatives and the study of their applications.
