Study on secondary metabolites of Penicillium expansum GY618 and their tyrosinase inhibitory activities

Twelve compounds were isolated from the rice fermentation extracts of Penicillium expansum GY618 by silica column chromatography, Sephadex gel column chromatography, ODS column chromatography and semi preparative HPLC methods. They were determined as 11-hydroxyl-penicitrinone F (1), penicitrinone F (2), betulin (3), erythrodiol (4), ergosterol (5), ergost-5α, 8α-epidioxy-6, 22-dien-3β-ol (6), (5α, 8α-epidioxy-(22E, 24R)-ergosta-6, 9(11), 22-trien-3β-ol) (7), 5α, 8α-epidioxy-(22E, 24R)-23-methylergosta-6, 22-dien-3β-ol (8), 5α, 8α-epidioxy- 23, 24(R)-dimethylcholesta-6, 9(11), 22-trien-3β-ol (9), dankasterone A (10), (17R)-4-hydroxy-17-methylincisterol (11) and ergosta-4, 6, 8(14), 22-tetraen-3-one (12), through mass spectrometer, nuclear magnetic resonance (NMR) and comparison with the literature. Compound 1 was a new compound and compounds 2-4, 6-12 were isolated from Penicillium expansum fungus for the first time. The tyrosinase inhibitory activity experiment showed that compounds 1, 3 and 12 showed certain inhibitory activity against tyrosinase with IC₅₀ values of (75 ± 9), (69 ± 8) and (64 ± 2) μmol·L^-1, respectively. The IC₅₀ of other compounds were all greater than 100 μmol·L^-1, while IC₅₀ of the positive control kojic acid was (46 ± 4) μmol·L^-1.