A new isocoumarin from metabolites of the endophytic fungus Alternaria tenuissima (Nees & T. Nees : Fr.) Wiltshire

A new isocoumarin, tenuissimasatin (1), was isolated from metabolites of the endophytic fungus Alternaria tenuissima (Nees &; T. Nees: Fr.) Wiltshire, which was isolated from the bark of Erythrophleum fordii Oliver, together with 11 known compounds (2–12). The structure and absolute configuration of 1 was determined by means of NMR and CD analysis. Compound 3 shows selective cytotoxic activity on human colon cancer cell HCT-8 (IC₅₀ = 1.78 μmol/L) by MTT test in vitro. Other compounds show no such activities (IC₅₀ > 10 μmol/L).