Molecular weight and anti-tumor activity of the water-soluble polysaccharides isolated by hot water and ultrasonic treatment from the sclerotia and mycelia of Pleurotus tuber-regium

Abstract

The sclerotia (S) and mycelia (M) of Pleurotus tuber regium were extracted, respectively, by hot water (h) and ultrasonication (s) to yield four water-soluble polysaccharides coded as Sh, Mh, Ss and Ms. All water-soluble polysaccharides were mixture of two fractions that contained predominantly polysaccharides with glucose as the major sugar and galactose and mannose as the minor component. The water-soluble extracts from mycelia seemed to have higher protein content than the ones from sclerotia. The ultrasonicated water extracts (Ms and Ss) contained glycan–chitin complexes with higher weight-average molecular weight ( M w) than that by hot water. Interestingly, the polysaccharides Mh and Sh extracted with hot water, which contained the major fractions with M w in the range of 40–80×10 4, exhibited stronger in vivo (Sarcoma 180 solid tumor implanted in BALB/c mice) and in vitro (HL-60 tumor cell culture) anti-tumor activities than that obtained by ultrasonication. In view of these results, the anti-tumor activities of the water-soluble polysaccharides isolated from both sclerotia and mycelia of P. tuber-regium depended on the method of isolation that affected the M w profile and conponent of the extracts. The effects of moderate M w and protein content of the polysaccharides on the improvement of the bioactivities could not be negligible.