Cholesterol and Sitosterol, Two Members of the Steroid Family That Differ in Structure by a Single Ethyl Group Yet Maintain the Right Balance between Plant and Animal Kingdoms

摘要

Cholesterol and sitosterol are two members of the steroid family, which molecular structures differ only by the presence of an ethyl substituent at the position 24 of the steroid skeleton. Cholesterol is mainly synthesized in large quantities in the liver of animals and only in small quantities by plants. In contrast sitosterol is only synthesized by plants. This tiny difference of an ethyl group between the two steroids structures have induced profound effects on the climatic changes during evolution, but plant sterols still have important effects on cholesterol metabolism on humans.