Two new xanthone derivatives from the algicolous marine fungus Wardomyces anomalus

A marine fungal isolate, identified as Wardomyces anomalus, was cultivated and found to produce two new xanthone derivatives, 2,3,6,8-tetrahydroxy-1-methylxanthone (1) and 2,3,4,6,8-pentahydroxy-1-methylxanthone (2), in addition to the known xanthone derivative 3,6,8-trihydroxy-1-methylxanthone (3) and the known fungal metabolite 5-(hydroxymethyl)-2-furanocarboxylic acid (4). The structures of all compounds were determined on the basis of extensive spectroscopic measurements (1D and 2D NMR, MS, UV, and IR). Compounds 1 and 4 showed significant antioxidant activities. The total extract and 1, 3, and 4 were shown to be inhibitors of p56(lck)tyrosine kinase.