Kojicone C, New Anti-Inflammatory Polyketide from Insect-Associated Fungus Aspergillus Versicolor

The chemical study of EtOAc extracts of the insect-associated fungus Aspergillus versicolor led to the isolation of a new polyketide kojicone C (1) and its precursor (2 R,4 R)-4-hydroxy-5-methoxy-2,4-dimethyl-2-[(2 R)- 2methylbutyryloxy]- 5-cyclohexen-1,3-dione (2). Kojicone C belongs to the rare tricycle cyclohexen-1,3-dione adduct class. The structures of 1 and 2 were determined by HRESIMS (high resolution electrospray ionization mass spectroscopy) data, 1D and 2D NMR (nuclear magnetic resonance) spectroscopic analysis, ECD (electronic circular dichroism) calculations, and CD exciton chirality method. Compound 1 exhibited moderate antiinflammatory activities that reduced LPS-induced NO production of RAW 264.7 cells (IC50 = 35.8 mu\M). It could also significantly inhibit LPS-induced mRNA expression of TNF-alpha, IL-1 beta, and IL-6 of this cell line at a concentration of 20 mu\M.