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.
Bilobalide is a biologically active terpenic trilactone present in Ginkgo biloba.
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.
Caryophyllene, more formally (−)-β-caryophyllene,(BCP), is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of Syzygium aromaticum (cloves), the essential oil of Cannabis sativa, copaiba, rosemary, and hops. It is usually found as a mixture with isocaryophyllene (the cis double bond isomer) and α-humulene (obsolete name: α-caryophyllene), a ring-opened isomer. Caryophyllene is notable for having a cyclobutane ring, as well as a trans-double bond in a 9-membered ring, both rarities in nature.
Sabinene is a natural bicyclic monoterpene with the molecular formula C10H16. It is isolated from the essential oils of a variety of plants including Marjoram, holm oak (Quercus ilex) and Norway spruce (Picea abies). It has a strained ring system with a cyclopentane ring fused to a cyclopropane ring.
Farnesol is a natural 15-carbon organic compound which is an acyclic sesquiterpene alcohol. Under standard conditions, it is a colorless liquid. It is hydrophobic, and thus insoluble in water, but miscible with oils.
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.
Isopentenyl pyrophosphate is an isoprenoid precursor. IPP is an intermediate in the classical, HMG-CoA reductase pathway and in the non-mevalonate MEP pathway of isoprenoid precursor biosynthesis. Isoprenoid precursors such as IPP, and its isomer DMAPP, are used by organisms in the biosynthesis of terpenes and terpenoids.
Farnesyl pyrophosphate (FPP), also known as farnesyl diphosphate (FDP), is an intermediate in the biosynthesis of terpenes and terpenoids such as sterols and carotenoids. It is also used in the synthesis of CoQ, as well as dehydrodolichol diphosphate.
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.
In enzymology, bornyl diphosphate synthase (BPPS) (EC 5.5.1.8) is an enzyme that catalyzes the chemical reaction
Capsidiol is a terpenoid compound that accumulates in tobacco Nicotiana tabacum and chili pepper Capsicum annuum in response to fungal infection. Capsidiol is categorized under the broad term of phytoalexin, a class of low molecular weight plant secondary metabolites that are produced during infection. Phytoalexins are also characterized as a part of a two pronged response to infection which involves a short term response consisting of production of free radicals near the site of infection and a long term response involving the production of hormones and an increase in enzymes to biosynthesize phytoalexins such as capsidiol.
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.
Aucubin is an iridoid glycoside. Iridoids are commonly found in plants and function as defensive compounds. Iridoids decrease the growth rates of many generalist herbivores.
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.
(+)-Costunolide is a naturally occurring sesquiterpene lactone, first isolated in Saussurea costus roots in 1960. It is also found in lettuce.
Geosmin synthase or germacradienol-geosmin synthase designates a class of bifunctional enzymes that catalyze the conversion of farnesyl diphosphate (FPP) to geosmin, a volatile organic compound known for its earthy smell. The N-terminal half of the protein catalyzes the conversion of farnesyl diphosphate to germacradienol and germacrene D, followed by the C-terminal-mediated conversion of germacradienol to geosmin. The conversion of FPP to geosmin was previously thought to involve multiple enzymes in a biosynthetic pathway.
Arglabin is a sesquiterpene lactone belonging to the guaianolide subclass bearing a 5,7,5-tricyclic ring system which is known to inhibit farnesyl transferase. It is characterized by an epoxide on the cycloheptane as well as an exocyclic methylene group that is conjugated with the carbonyl of the lactone. Arglabin is extracted from Artemisia glabella, a species of wormwood, found in the Karaganda Region of Kazakhstan. Arglabin and its derivatives are biologically active and demonstrate promising antitumor activity and cytoxocity against varying tumor cell lines.
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.
