Production of monapinones by fermentation of the dinapinone-producing fungus Penicillium pinophilum FKI-3864 in a seawater-containing medium

Abstract

Five new monapinones, including a dinapinone monomer, were isolated from the culture broth of the dinapinone-producing Penicillium pinophilum FKI-3864 in a medium modified to contain seawater. The structures of these monapinones were elucidated by various NMR experiments. Monapinones possessed the same dihydronaphthopyranone skeleton as the dinapinones, with different hydroxyalkyl chains: monapinone A was identified as the monomeric portion of the atropisomer dinapinones A1 and A2, and monapinones A and B showed weak inhibition of triacylglycerol (TG) synthesis in intact mammalian cells, whereas the others showed almost no effect on TG synthesis. The Journal of Antibiotics (2011) Keywords: dinapinone monomer; monapinone; Penicillium pinophilum; seawater-containing medium; triacylglycerol biosynthesis INTRODUCTION During our screening program to discover inhibitors of triacylglycerol (TG) synthesis using intact Chinese hamster ovary-K1 (CHO-K1) cells, dinapinones A1 (6) and A2 (7) were isolated from the culture broth of Penicillium pinophilum FKI-3864. 1 These are atropisomers formed from two monomers with the same dihydronaphthopyranone structure. 1,2 Interestingly, the mixture (1:1) of 6 and 7 showed full inhibitory activity against TG synthesis in CHO-K1 cells (IC 50 , 0.054 mM), although 6 or 7 alone showed less potent activity (IC 50 , 0.65 or 412 mM, respectively).Through our study of the culture conditions for dinapinone production, we found that five new compounds containing the dinapinone monomeric unit-designated monapinones A (1) to E (5) (Figure 1) were produced when the dinapinone-producing fungus was cultured in the original medium supplemented with seawater. Interestingly, compounds 1-5 were produced by the fungus only in the original production medium supplemented with seawater, whereas 6 and 7 were produced very slightly in the same medium. The structure elucidation of 1 and 2, including their absolute stereochemistry, will be described in detail elsewhere. 2 In this study, the fermentation, isolation, structure elucidation of 3-5 and TG inhibitory activity of monapinones are described.

Structures and absolute stereochemistry of dinapinones A1 and A2, inhibitors of triacylglycerol synthesis, produced by penicillium pinophilum FKI-3864

“…Study of the culture conditions indicated that monapinones were produced by the fungus, when the strain was fermented in the original dinapinone production medium supplemented with seawater. 7,8 In this study, we demonstrated that 1 …”

“…Study of the culture conditions indicated that monapinones were produced by the fungus, when the strain was fermented in the original dinapinone production medium supplemented with seawater. 7,8 In this study, we demonstrated that 1 and 2 are atroposomers consisting of dimers of 3 and that the absolute stereochemistry of 1 and 2 is elucidated by conversion of structure-defined 3 to 1 and 2.…”

“…7,8 From a study of the culture conditions, monapinones were found to be produced only in a dinapinone-producing medium supplemented with seawater. 8 As described in this study, the structures of 1 to 4 were elucidated by various spectral analyses. Compounds 1 and 2 with the same planar structure were found to be dimers of 3.…”

“…6 Fermentation of dinapinone A1 (1) and A2 (2) and monapinone A (3) and B (4) The culture conditions for the production of 1 to 4 were described previously. 7,8 Strain FKI-3864 was fermented in media containing seawater or tap water. Dimers 1 and 2 (12 mg l À1 ) were produced for 10-20 days in tap water-containing medium.…”

“…8 LCUV analysis-guided fractionation of the culture broth of the fungus, including organic solvent extraction, ODS gel column chromatography and reversed phase (C18) HPLC, yielded 3 and 4. …”