Biotransformation of lipids Despite the technical emphasis of this chapter, we have included some examples 9.2 The structure, roles and abundance of sterols and steroids Some examples of sterols and steroids are given in Figure g.1. Also included in this Figure are some examples of bile salts. You should realise that the structures shown are steroidal ring only a few of the many hundreds of compounds which occur in nature. All of these stucture compounds include the steroidal ring structure which is numbered as shown belor D B Substituents are designated as in the a configuration if they are below the plane of the steroidal nucleus, and as p if above the plane Thu whilst 3B hydroxy Examine Figure 9.1 and see if you can distinguish between the roles of the sterols (at the top of the figure)and the C18, Cig, Ca and Ca4 steroidal compounds In general, the sterols perform a structural function, for example as components of the lipid layers of membranes. The C18, C19 and C21 steroids mainly perform an endocrine function. In other words they are hormones. The bile salts( C24-steroids) fulfil a functional role in digestion in animals.Biotransformation of lipids 295 Despite the technical emphasis of this chapter, we have included some examples of industrial processes. 9.2 The structure, roles and abundance of sterols and steroids Some examples of sterols and steroids are given in Figure 9.1. Also included in this Figure are some examples of bile salts. You should realise that the structures shown are only a few of the many hundds of compounds which occur in nature. All of these compounds include the steroidal ring structure which is numbered as shown below. steroidal ring smare - Substituents are designated as in the a configuration if they are below the plane of the steroidal nucleus, and as 0 if above the plane: Thus is 3a hydroxy - whilst is 38 hydroxy - Examine Figure 9.1 and see if you can distinguish between the roles of the sterols n (at the top of the figure) and the C18, (219, Cn and CN steroidal compounds. In general, the sterols perform a structural function, for example as components of the lipid layers of membranes. The Cis, Ci9 and C21 steroids mainly perform an endocrine function. In other words they are hormones. The bile salts (Czlr-steroids) fulfil a functional role in digestion in animals