New isochaetochromin, an inhibitor of triacylglycerol synthesis in mammalian cells, produced by Penicillium sp. FKI-4942: I. Taxonomy, fermentation, isolation and biological properties

A new bis-naphtho-γ-pyrone isomer named isochaetochromin A 1 was isolated along with known isochaetochromins B 1 and B 2 from the culture broth of Penicillium sp. FKI-4942 by solvent extraction, silica gel column chromatography and HPLC. Among them, isochaetochromin B 1 showed the most potent inhibitory activity of triacylglycerol synthesis with an IC 50 value of 5.6 μ M , followed by isochaetochromins B 2 (IC 50 , 11 μ M ) and A 1 (33 μ M ).