83-2 |
|
S. M. WONG, Dept. of Biology, The Chinese Univ.of Hong Kong, Shatin, New Territories, Hong Kong, China and P. C. K. Cheung, Food and Nutritional Sciences Programme, The Chinese Univ. of Hong Kong, Shatin, New Territories, HongKong, China. Pleurotus tuber-regium (PTR) is an edible fungus which belongs to the Tricholomataceae basidiomycetes. It had been reported that non-starch polysaccharides isolated from the mycelium and sclerotium of PTR possessed in vivo antitumor activities. However, there is very little study on the in vitro antitumor efficacy of the mushroom polysaccharides isolated from the different developmental stages of PTR including mycelia, culture medium, sclerotia and fruiting bodies. The present project will focus on such comparative study with emphasis on structure-activity relationship. Non-starch polysaccharides extracted by hot water from PTR, were purified by ethanol precipitation/dialysis and their monosaccharide composition, carbohydrate and protein content were determined by gas chromatography, phenol-sulphuric method, and Lowry method, respectively. For in vitro study of antiproliferation and cytotoxicity, dye exclusion method was used for suspended cells (HL-60) while colorimetric MTT method was applied for adherent cells (MCF-7 and HepG2). All non-starch polysaccharides isolated from the mycelium and sclerotium of PTR were mainly glucans except the exo-polysaccharides which contained mannose as the major sugar. Polysaccharides from mycelium, fruiting body and exo-polysaccharides contained relatively larger amount of protein while sclerotial polysaccharides contained very little amount. Hot-water soluble exo-polysaccharides from culture medium and ethanol-precipitated mycelial polysaccharides showed significant antiproliferation to HL-60 cells (100% and 21% at 400mg/ml, respectively) but only the former inhibited the proliferation of MCF-7 cells (80% at 400mg/ml). Hot water soluble polysaccharides extracted from the sclerotia of PTR demonstrated in vitro antitumor activities against HL-60 and HepG2 cells but not Vero cells. The different in vitro antitumor effect towards cancer cell lines of mushroom polysaccharides isolated from their different developmental stages are related to their difference in chemical composition.
Session 83, Food Chemistry: Antioxidant and bioactive agents
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |