Biochemistry of Terpenoids: Monoterpenes, Sesquiterpenes and Diterpenes

Abstract

AbstractTerpenoids represent the largest class of secondary metabolites and usually do not contain nitrogen or sulfur in their structures. Many terpenoids serve as defence compounds against microbes and herbivores and/or are signal molecules to attract pollinating insects, fruit‐dispersing animals or predators which can destroy insect herbivores. As a consequence, many terpenoids have pronounced pharmacological activities and are therefore interesting for medicine and biotechnology. The first part of the biosynthesis is the generation of a C5 unit, such as isopentenyl diphosphate (IPP) or dimethylallyl diphosphate (DMAPP). Two independent pathways have been discovered that can produce the C5 unit: the mevalonate and the methylerythritol phosphate (MEP) pathway. Depending on the number of C5 units, we distinguish hemiterpenes C5, monoterpenes including iridoids (C10), sesquiterpenes (C15), diterpenes (C20), sesterterpenes (C25), triterpenes (including steroids) (C30), tetraterpenes (C40) and polyterpenes (>C40). The biosynthesis (including enzymes, genes and their regulation) of mevalonate and the methylerythritol phosphate pathway and the consecutive pathways leading to mono‐, sesqui‐ and diterpenes are discussed in this chapter in detail.