The chemistry of steroid acids from Cephalosporium acremonium

Abstract

Cephalosporin P 1 ( 1a), isocephalosporin P 1 ( 1c) and monodesacetyl cephalosporin P 1 ( 2a) have been isolated from the organic extract of the fermentation broth of Cephalosporium acremonium. The acids 1a and 2a were obtained in 18% and 3% yield, respectively, from the crude concentrated butyl acetate extract. The structure and stereochemistry of 1a, 1c, and 2a were established by chemical and spectral studies. Compound 1a, c, and 2a are steroid acids with a trans-syn-trans B-boat conformation, each possessing three angular Me groups and one Me group attached to a secondary C atom. The placement and stereochemistry of the two OAc groups and two OH groups of 1a and 1c and also one OAc groups and three OH groups of 2a are established. Additional data are presented which establish the side-chain structure at C-17 position and confirm the trans-fused A/B ring junction. Some novel LAH reduction products from 1b, 2b and 5 were observed. The antibacterial activities of 1a and 2a and other derivatives are also presented.