Two new diastereomeric sterigmatocystin derivatives from the culture broth of Hypomyces sp.

Two new sterigmatocystin derivatives, named hyposterigmatocystin A and B (1 and 2), and three known compounds, 3a,12c-dihydro-8,12c-dihydroxy-6-methoxy-7H-furo[3′,2′:4,5]furo[2,3-c]xanthen-7-one (3), sterigmatocystin (4), and secosterigmatocystin (5) were isolated from the culture broth of Hypomyces sp. using various column chromatography techniques. The chemical structures of the isolated compounds were elucidated using spectroscopic methods and comparison with reported data. The isolated compounds were evaluated for their antibacterial activities against four Gram-positive bacteria, exhibiting MIC values ranging from 12.5 to exceeding 200 μg mL⁻¹, with sterigmatocystin (4) being the most potent.