Purification, characterization and tyrosinase inhibition activity of polysaccharides from chestnut (Castanea mollissima Bl.) kernel

Abstract The present paper aimed to obtain the polysaccharides with potent tyrosinase inhibitory activity from chestnut kernel. The ultrasound extracted polysaccharide fractions 1-1 (UEP1-1) and UEP2-1 were obtained by successive ultrasound-assisted-extraction, DEAE-52 and Sephadex G-100 chromatography. The Fourier transform infrared spectrum revealed that both UEP1-1 and UEP2-1 had the characteristic absorption peaks of polysaccharides. The degree of esterification of UEP1-1 (52.4%) and UEP2-1 (49.0%) was higher than that of the crude UEP (33.0%), indicating that the gel properties of the polysaccharides changed after purification. The x-ray diffraction patterns of UEP1-1 and UEP2-1 suggested that they were semi-crystalline polymers with a degree of crystallinity of 23.9 and 35.8%, respectively. The weight-average molecular weight (M w ) of UEP1-1 and UEP2-1 was 75.4 and 59.9 kDA, respectively. The monosaccharide composition of UEP1-1 and UEP2-1 was glucose, galactose, arabinose, mannose, xylose, rhamnose and fructose with different proportions. UEP1-1 displayed a dose-dependent inhibitory effect on tyrosinase activity, and the inhibition mode was found to be competitive.