Description
Steroids are natural chemicals widely found in nature. It is a kind of lipid compound and characterized by a four ring parent nucleus of all steroids derived from the acetyl coenzyme A synthesis pathway. Different steroids are only diverse in their functional groups that attached to their rings, and their basic structure is the cyclopentane polyhydric phenanthrene. Commonly used steroids include phytosterols, bile acids, C21 steroids, insect metamorphic hormones, cardiac glycosides, steroidal saponins, steroid alkaloids, and toad venom.