Two new polyketides from the ascomycete fungus Leptosphaeria sp.

Leptosphaerins H and I ( 1 and 2 ), two new xanthone derivatives, and six known compounds, leptosphaerin F ( 3 ), monodictysin B ( 4 ), norlichexanthone ( 5 ), leptosphaerin D ( 6 ), moniliphenone ( 7 ) and emodinbianthrone ( 8 ) have been isolated from a scale-up fermentation of the ascomycete fungus Leptosphaeria sp. Their structures were primarily elucidated by interpretation of NMR spectroscopic data. The absolute configuration of 1 was assigned using the modified Mosher method, whereas that of C-8a in 2 was determined via the CD data. Compound 6 showed modest cytotoxicity against a panel of three human tumor cell lines.