Fucidin

Abstract

This volume attests to the fact that we are now entering a period in which our knowledge about the mode of action of antibiotics is increasing at a rapid rate. This increase is largely the result of an increased understanding of cellular physiology and better techniques for its study. However, there have been but few studies on the mechanism of action of the steroid antibiotics, probably because only a few are known. In brief, there are two antifungal steroid antibiotics: viridan produced by Trichoderma iride, and eburicoic acid produced by a basidiomycete; and three antibacterial steroid antibiotics: helvolic acid produced by Aspergillus fumigatus, cephalosporin P₁ produced by Cephalosporium salmosynnematum, and fusidic acid produced by Fusidium coccineum. At this time, fusidic acid seems to be the steroid antibiotic with greatest therapeutic potential. It was isolated by Godtfredsen et al. (1962), and tentatively characterized by Godtfredsen and Vangedal (1962); recently the chemical structure has been modified to that shown in Fig. 1 (Godtfredsen, personal communication). Fig. 1 shows that the three antibacterial steroid antibiotics, helvolic acid, fusidic acid, and cephalosporin P₁, are chemically related. They each contain a tetracyclic ring with an identical side chain which has an alpha, beta unsaturated carboxylic acid and a beta oriented acetoxyl group on carbon 16.