Polysaccharide isolation and in vitro evaluation of the possible antiproliferative capacity of the edible mushrooms Polyporus tenuiculus.

OMARINI, A. ; TASAT, D., ; VALENTICH, M; ALBERTÓ, E.

La Plata

Congreso; XVI Congreso Italo-latinoamericano de Etnomedicina- SILAE; 2007

SILAE-Universidad de La Plata,

Higher Basidiomycetes produce biologically active compounds (principally polysaccharides) which are mainly concentrated in the fruit bodies and exhibit promising antitumoral activity. The aim of this study is to characterize and evaluate the possible in vitro antiproliferative capacity of the fungal extracts obtained from fruit bodies of native specie widely distributed in the north of Argentine: Polyporus tenuiculus (Polyporales, Basidiomycetes). In order to obtain fruit bodies P. tenuiculus was cultivated on Salix sawdust with soybean flour and wheat bran as supplements. Polysaccharides were isolated from harvested mature fruit bodies following Yap A. and Ng M. methodology (2001). Fruit bodies were frozen at -20 ºC and powdered. A partial purification of the polysaccharides was realized; two extractions with distilled water (100 ºC, 4 h) and two precipitations with ethanol (95 %). Two fractions (P1 and P2) and two supernatants were obtained. Total sugar and protein content were determinated in P1 and P2 by Anthrone and Bradford method respectively. Cultured human breast cancer cells (ZR 75-1, ATCC, VA, USA) were used to evaluate cell proliferation and apoptosis. Cells (2 x 104) were seeded in 96-well plates and maintained for 24 h with D-MEM (10% FCS and 1% pen-strep) at 37 ºC and treated with P1 or P2 (25-100 µg/ml) during 24 and 48 h. Cultured cells were fixed with methanol-acetic (3:1), stained with crystal violet and solubilized with SDS. Optical density was evaluated at 570 nm; apoptosis was studied by the fluorescent dye Hoechst (33258). The results obtained show that in our in vitro system fractions P1 and P2 failed to inhibit tumor cell growth and no apoptotic figures were clearly found, although for P1 25 µg/ml cells elicited a more condensated cytoplasm and nuclei suggesting a possible role in the apopotosis process. Conclusions: Further studies should be done in order to determine possible antiproliferative capacity of fraction P1 of P. tenuiculus.