Multiple Roles for Plant Sterols

Abstract

In certain ways all sterols are the same, yet in other respects they are quite different. To some extent we understand the reason for the similarities in that sterols must ``fit'' into the phospholipid leaflet which comprises the monolayer component of the common bilayer arrangement of natural membranes1. On the other hand, the reason or reasons for the differences in structure are still elusive. Although we are making a beginning, we still do not yet know why it is that, for instance, people have cholesterol as their major sterol1, while in flowering poinsettia plants only about half the sterol is cholesterol2, in cottonseed oil 93{\%} of the sterol is 24$α$-ethylcholesterol (sitosterol)1, and in the vine, Clerodendrum splendens, nearly all of the sterol is the 22, 25 (27)-bisdehydro derivative of the 24$β$-epimer of sitosterol, viz., 25 (27)-dehydroporiferasterol3.