Steroids contain the backbone of cyclopentanoperhydrophenanthrene with four hydrocarbon rings in their structures. They widely exist in tissues of animals and plants and have vital significance in living activities. Steroids include sterol and its derivations. Zymosterol, zoosterol, and phytosterol are the three major forms of sterol. Phytosterol is involved in metabolism of plants. Cholesterol, one of the zoosterols, plays an important role in sustaining the physical state of biomembrane. Besides, it is involved in atherosclerosis. Bile acid and vitamin D are the commonly seen sterol derivations, both of which are important to the growth and development.
Terpenes are linear or cyclic hydrocarbons that are chemically related to steroids: they are often the precursor of steroids in biosynthesis. Although terpenes are in small quantities in cell, it has pivotal biology functions in cell signaling, metabolism, and biosynthesis. In addition, terpenes are also useful active ingredients in agricultural pesticides.
