Marine microbes, especially those living in close association with macroorganisms represent an important source of pharmacologically active natural products1. Investigation of the marine-derived fungus Nodulisporium sp. located in the inner tissue of a marine algal species led to the isolation of the new natural product (3R)-7-hydroxy-5-methylmellein (1) and a new polyketide with a dimeric xanthone structure (2). The new compound 1 is distinguished from other natural melleins2 by its rare 7,8-ortho hydroxy substitution. The new dimeric xanthone 2, presumably related to anthraquinones concerning its biosynthesis3, consists of two subunits similar to ergochrome F. In one of these the lactone ring is cleaved to give a 4-hydroxy-butyric acid methyl ester moiety. The monomeric substructures are connected asymmetrically via carbon 2 and 4'. The stereochemistry of the four chiral centres and the chiral axis is still under investigation.
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References: 1. König, G.M. et al. (2006), ChemBioChem. 7: 229–238. 2. Krohn, K. et al. (1997), Phytochem. 45: 313–320. 3.Tabata, N. et al. (1996), J. Antibiot. 49: 267–271.
