New xanthone and sesquiterpene derivatives from Scopulariopsis sp., a marine-derived fungus isolated from the Red Sea hard coral Stylophora sp.

Abstract

Marine natural products with their diverse unique bioactivities represent a capacious gold mine for the discovery of lead compounds that could be a useful drug entity for the treatment of various malicious diseases. In the last decade, with an increasing interest in the drug discovery from marine system, emphasis has been done mainly concerning various ecosystems exist in the wide marine environment, including hitherto unexploited and geographically and taxonomically undescribed organisms [1]. Recently, an increasing interest was directed toward marine-derived fungi to be an enormous source of structurally novel and potent bioactive metabolites [2]. The marine-derived fungus Scopulariopsis sp. was isolated from the inner tissues of a hard coral Stylophora sp. collected from the Red Sea, and grew on a solid rice medium. Chemical investigation of the EtOAc extract which exhibited considerable cytotoxic activity against both L5178Y cell line and A2870 cell line and anti-tubercular activity, led to the isolation of six new secondary metabolites including three xanthone derivatives (1-3), two phenolic bisabolane-type sesquiterpenoids (4 and 5), and one alkaloid (6). In addition, fourteen known compounds including six xanthone derivatives (7- 12), three bisabolane-type sesquiterpenoids (13-15), four bi-phenyl ether derivatives (16-19) and ergosterol (20) were also identified. Structures of the isolated compounds were established through extensive analysis of the 1D, 2D NMR as well as MS data, and by comparison with the literature.