Isoprenoids are very stable and persistent substances

Isoprenoids are very stable and persistent substances

Little is known about the catabolism of isoprenoids in plants. Biologically active compounds, such as phytohormones, are converted by the introduction of additional hydroxyl groups and glucosylation into inactive derivatives, which are often deposited in the vacuole. It is questionable whether, after degradation, isoprenoids can be recycled in a plant. Some isoprenoids are remarkably stable. Large amounts of isoprenoids are found as relics of early life in practically all sedimentary rocks as well as in crude oil. In archaebacteria, the plasma membranes contain glycerol ethers with isopre-noid chains instead of fatty acid glycerol esters. Isoprenoids are probably constituents of very early forms of life.