英文Terpenoids.ppt

Terpenoids  INTRODUCTION Terpenoids are the secondary metabolites synthesized by plants, marine organisms and fungi by head to tail joining of isoprene units. They are also found to occur in rocks, fossils and animal kingdom. The terpenoids, sometimes referred to as isoprenoids, are a large and diverse class of naturally-occurring organic chemicals similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways. Most are multicyclic structures that differ from one another not only in functional groups but also in their basic carbon skeletons. These lipids can be found in all classes of living things, and are the largest group of natural products.  Mnonoterpenoids 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. Biochemical modifications such as oxidation or rearrange-ment produce the related monoterpenoids. Mnonoterpenoids Acyclic monoterpenoid: Acyclic monoterpenoid Acyclic monoterpenoid Biosynthetically, isopentenyl pyrophosphate(异戊烯焦磷酸) and dimethylallyl pyrophosphate (二甲基丙烯焦磷酸酯) are combined to form geranyl pyrophosphate (牻牛儿醇焦磷酸酯). Acyclic monoterpenoid Elimination of the pyrophosphate group leads to the formation of acyclic monoterpenes such as ocimene and the myrcenes. Acyclic monoterpenoid Hydrolysis of the phosphate groups leads to the prototypical acyclic monoterpenoid geraniol. Acyclic monoterpenoid Additional rearrangements and oxidations provide compounds such as citral (柠檬醛), citronellal(香茅醛), citronellol(香茅醇), and many others. Acyclic monoterpenoid Many monoterpenes found in marine organisms are halogenated(卤代的), such as halomon. Monocyclic monoterpenoid In addition to linear attachments, the isoprene units can make connections to form rings. The m