Polyhydroxylated steroids from an endophytic fungus, Chaetomium globosum ZY-22 isolated from Ginkgo biloba

A novel polyhydroxylated C-29-sterol, 25 xi-methyl-22-homo-5 alpha-cholest-7,22-diene-3 beta,6 beta,9 alpha-triol, designated globosterol (1), together with one known tetrahydroxylated ergosterol (22E, 24R)-ergosta-7,22-diene-3 beta,5 alpha.6 beta,9 alpha-tetraol (2) has been isolated from the cultures of an endophytic fungus, Chaetornium globosum ZY-22 originated from the plant Ginkgo biloba. The structures and relative configurations of I and 2 were established on the basis of extensive spectroscopic analyses including 1 D and 2D NMR (H-1-H-1 COSY, HSQC. HMBC, and NOESY) experiments and comparison with the literature. Globosterol (1) possesses an unprecedented 25-methyl Delta(22)-C-10-side chain and Delta(7)-3 beta,6 beta,9 alpha-hyclroxy-steroid nucleus, which represents the first example for C-29-steroids of the group. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.