Polyterpenoid

Polyterpenoid is a type of terpenoid, which is a large and diverse class of naturally occurring organic chemicals derived from five-carbon isoprene units assembled and modified in thousands of ways. Polyterpenoids are a subclass of terpenoids that consist of long chains of many isoprene units. They are found in a variety of organisms, including plants, animals, and microorganisms.

Structure and Biosynthesis

Polyterpenoids are composed of multiple isoprene units, with each unit consisting of five carbon atoms. The isoprene units in a polyterpenoid can be arranged in a variety of ways, leading to a vast diversity of structures. The biosynthesis of polyterpenoids involves the polymerization of isoprene units, which is catalyzed by enzymes known as terpene synthases.

The first step in the biosynthesis of polyterpenoids is the formation of the five-carbon building blocks, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), from acetyl-CoA via the mevalonate pathway or the non-mevalonate pathway. These five-carbon units are then condensed to form the ten-carbon geranyl diphosphate (GPP), the fifteen-carbon farnesyl diphosphate (FPP), and the twenty-carbon geranylgeranyl diphosphate (GGPP). These larger units can then be further polymerized to form the various polyterpenoids.

Functions

Polyterpenoids have a wide range of biological functions. In plants, they serve as defensive compounds against herbivores and pathogens, as well as attractants for pollinators. Some polyterpenoids also have antimicrobial properties. In animals, polyterpenoids are involved in various physiological processes, including inflammation and cholesterol metabolism. Some polyterpenoids, such as the diterpenoids, are used in traditional medicine for their therapeutic properties.

Examples

Examples of polyterpenoids include the rubber produced by the rubber tree (Hevea brasiliensis), which is a polyisoprene, and the guttapercha, a polyisoprene produced by trees of the Palaquium genus. Other examples include the carotenoids, which are tetraterpenoids involved in light absorption in photosynthesis and in the coloration of fruits and flowers.

See also

• Terpenoid
• Isoprene
• Terpene synthase
• Mevalonate pathway
• Non-mevalonate pathway
• Diterpenoid
• Carotenoid

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