5-Methylmellein and nectriapyrone, two new monoamine oxidase inhibiters

In the course of screening for monoamine oxidase (MAO) inhibitors among mic robial metabolites, we found that unidentified fungal strain 8082 produced 5-methylmellein, which slows potent inhibitory activity against mouse brain MAO. Although, 5-methylmellein has been previously isolated as a phytotoxi n, its MAO inhibitory activity has not hitherto been reported. During the p urification of 5-methylmellein, we also isolated nectriapyrone as a minor c omponent. Nectriapyrone has not been previously reported as MAO inhibitor e ither. We describe the inhibitory activities of 5-methylmellein and nectria pyrone on MAO. 5-Methylmellein and nectriapyrone inhibited MAO in a dose-de pendent manner and their IC50 values were 1.06 and 8.9 mu M respectively. M ed Sci Res 27:463-465 (C) 1999 Lippincott Williams & Wilkins.