Abstract:
Chemical exploration of a crude cell extract of the insect pathogenic fungus Hirsutella kobayasii BCC 1660 led to the identification of a dithiodioxopiperazine (42), a new cyclohexadepsipeptide, named hirsutellide A (44), together with a known xanthone (43). The absolute stereochemistry of the amino acid moiety in 44 was defined by Marfey′s method. The stems of Getonia floribunda provided two new macrocyclic lactones, combretastatins D-3 (124) and D-4 (125), together with a known compound, arjunolic acid (126). Combretastatin D-3 (124) exhibited cytotoxicity towards small cell lung cancer, while arjunolic acid (126) exhibited antimalarial activity. Chemical exploration of Camchaya calarea (whole plant) led to the isolation of nine known sesquiterpene lactones, 185-193, and a known caffeic acid methyl ester (194). These compounds showed interesting biological activities, e.g. antimalarial, antituberculosis, and cytotoxicity towards NCI-H187, KB, BC and Vero cell lines.