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Secondary metabolites from the fungus Monascus kaoliang and inhibition of nitric oxide production in lipopolysaccharide-activated macrophages

Cheng, Ming-Jen, Wu, Ming-Der, Su, Yung-Shun, Yuan, Gwo-Fang, Chen, Yen-Lin, Chen, Ih-Sheng
Phytochemistry letters 2012 v.5 no.2 pp. 262-266
Monascus kaoliang, acetates, ethanol, fungi, lipopolysaccharides, macrophages, minimum inhibitory concentration, mutants, nitric oxide, nuclear magnetic resonance spectroscopy, red yeast rice, secondary metabolites, spectral analysis
Phytochemical analysis of the n-BuOH-soluble fraction of the 95% EtOH extract of the red yeast rice fermented with the yellow mutant of the fungus Monascus kaoliang BCRC 31506 led to the isolation of one new azaphilone metabolite, designated as monascuskaolin (1), along with 9 known compounds (2–10). Monascuskaolin (1) contains an isochroman-6-one azaphilone skeleton connected with one γ-lactone ring, one propan-2-yl acetate moiety, and one decanoyl side chain. Their structures were elucidated by detailed spectroscopic analyses, including HRESIMS and 1D and 2D NMR data (COSY, HSQC, HMBC, and NOESY). The relative configuration of 1 was confirmed by NOESY experiment. Other known compounds were identified by comparison of their spectral data with the literature data of authentic samples. Inhibitory effects of some isolates on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophages were evaluated. Compounds 1–4 showed inhibition on NO production in LPS-stimulated RAW 264.7 macrophages in vitro, showing MIC values of 7.62, 18.78, 26.72, and 32.80μg/mL, respectively.