Chapter 12 terpenoids and steroids

Isoprene itself does not undergo the building process, but rather activated forms, isopentenyl pyrophosphate (IPP or also isopentenyl diphosphate) and dimethylallyl pyrophosphate (DMAPP or also dimethylallyl diphosphate), are the components in the biosynthetic pathway. IPP is formed from acetyl-CoA via the intermediacy of mevalonic acid in the HMG-CoA reductase pathway . An alternative, totally unrelated biosynthesis pathway of IPP is known in some bacterial groups and the plastids of plants, the so-called MEP(2-Methyl-D-erythritol-4-phosphate)-pathway, which is initiated from C5-sugars. In both pathways, IPP is isomerized to DMAPP by the enzyme isopentenyl pyrophosphate isomerase.

Essential oils and other biopesticides are becoming a new trend for pest management in modern farming and organic agriculture. For 2 decades, EOs are used as insecticides to control insects, however, they have not reached their full potential because they are rapidly volatile and low residual activity. They are considered safe, environment-and-eco-friendly, compatible with biological control programs and have low mammals toxicity. Also, EOs are available worldwide for their low to moderate cost. The main active constituents with insecticidal activity are monoterpenes, sesquiterpenes and related phenylpropenes. The EOs can be applied as pesticides as they are or as their active components "Active ingredient" or as co-adjutants in pesticide formulations. However, they can be acted as a contact insecticide, causing changes in the pathways of biochemical metabolism of the insect, knockdown and rapid death 72 , fumigants 73 , repellents 74 and antifeedant 71 .

Chapter 12 terpenoids and steroids

chapter 12 terpenoids and steroids


chapter 12 terpenoids and steroidschapter 12 terpenoids and steroidschapter 12 terpenoids and steroidschapter 12 terpenoids and steroidschapter 12 terpenoids and steroids