Fusidic acid derivatives from the endophytic fungus Acremonium pilosum F47

Fusidic acid, a representative member of fungal fusidane triterpenoids, has been clinically used as an antibiotic. In the present study, fusidic acid (1), and its known analogs 16-desacetylfusidic acid (2) and 3β,20-dihydroxy-protosta-16,24-dien-29-oic acid (4), together with one new derivative acremonidiol A (3), were isolated from the endophytic fungus, Acremonium pilosum F47. Their structures were determined by MS and NMR. The spectroscopic data of 2 are firstly reported here. The antibacterial efficacies of 1-4 were evaluated against four selected Gram-positive or Gram-negative bacteria. As expected, only compound 1 showed strong inhibitory effect on Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis.