Ent-steroids chemistry and biology

Ent-steroids, the enantiomers of naturally-occurring steroids, are useful tools for distinguishing between receptor and non-receptor mediated actions of steroids. In particular, ent-steroids are useful for evaluating the relative importance of the direct (receptor binding) and indirect (membrane perturbation) effects of steroids on the function of membrane-bound proteins. A distinction between these two processes can be made on the basis of the different degrees of enantioselectivity expected for the two types of steroid actions. Receptor binding of steroids is expected to be enantioselective, whereas steroid effects on membrane properties are not. The synthesis of ent-steroids and examples of their use in biological studies are presented.