Dinapinones, novel inhibitors of triacylglycerol synthesis in mammalian cells, produced by Penicillium pinophilum FKI-3864.

Dinapinone A, a novel biaryl dihydronaphthopyranone, was isolated from the culture broth of Penicillium pinophilum FKI-3864 by solvent extraction, silica gel and ODS column chromatography and HPLC. Dinapinone A showed very potent inhibition of triacylglycerol (TG) synthesis in intact Chinese hamster ovary K1 (CHO-K1) cells with an IC(50) value of 0.097 μM. Dinapinone A was found to be a mixture of stereoisomers, resulting in its separation into dinapinones A1 and A2 by HPLC using a C30 reverse-phase column. Dinapinone A1 did not inhibit TG synthesis in CHO-K1 cells even at 12  μM, and dinapinone A2 showed less potent inhibition (IC(50); 0.65  μM) than dinapinone A; however, a mixture of isolated dinapinones A1 and A2 (a 1:1 ratio) recovered the potent TG inhibitory activity (IC(50); 0.054  μM). A similar effect of dinapinone on TG synthesis in intact Raji cells was also observed.