Feigrisolides A, B, C and D, new lactones with antibacterial activities from Streptomyces griseus

Four new lactone compounds, named feigrisolides A to D (1 to 4), have been isolated from Streptomyces griseus. The chemical structures were determined by detail analysis of their spectroscopic data and chemical transformation s. Structurally, the feigrisolides A (1) and B (2) are hepta-lactones, feig risolide C (3) and D (4) are 16-membered macrodiolides. Biological studies showed that feigrisolide B (2) exhibited strong antibacterial, as well as m edium cyctotoxic, and antiviral activities. Feigrisolides A (1), C (3) and D (4) are medium inhibitors of 3 alpha-hydroxysteroid-dehydrogenase (3 alph a-HSD) inhibiting activity.