Polycyclic tetrahydroxanthones from Streptomyces chrestomyceticus BCC 24770

Three polycyclic tetrahydroxanthones, chrestoxanthones A−C, together with known albofungin and chloroalbofungin were isolated from the actinomycete Streptomyces chrestomyceticus BCC 24770. Their structures were elucidated by extensive spectroscopic analyses. Chrestoxanthone A was active against Curvularia lunata and Alternaria brassicicola, while all other isolated metabolites displayed broad antifungal activities against C. lunata, A. brassicicola, Colletotrichum capsici, and Colletotrichum gloeosporioides.