Biosynthesis of Steroids and Steroid-Related Compounds

The word steroid was initially used to describe cholesterol discovered in gallstones [1]. Cholesterol, an amorphous solid, got its name from the ancient Greek words chole ("bile") and stereos ("solid"). Structurally, cholesterol (1) has a tetracyclic structure consisting of three fused six-membered and one five-membered ring, as shown in Figure 16.1. Steroids contain a basic skeleton of 17 carbon atoms. The functional groups attached to C-17 vary considerably, with the most common locations being C-3, C-4, C-7, C-11, C-12, and C-17. The presence of cholesterol in arterial plaques was detected for the first time in 1843 [2]. Later, it was discovered in animals and plants [3].