Aurantoside K, a New Antifungal Tetramic Acid Glycoside from a Fijian Marine Sponge of the Genus Melophlus

A new tetramic acid glycoside, aurantoside K, was isolated from a marine sponge belonging to the genus Melophlus. The structure of the compound was elucidated on the basis of spectroscopic analysis (H-1 NMR, H-1-H-1 COSY, HSQC, and HMBC, as well as high-resolution ESILCMS). Aurantoside K did not show any significant activity in antimalarial, antibacterial, or HCT-116 cytotoxicity assays, but exhibited a wide spectrum of antifungal activity against wild type Candida albicans, amphotericin-resistant C. albicans, Cryptococcus neoformans, Aspergillus niger, Penicillium sp., Rhizopus sporangia and Sordaria sp.