RESUMEN
The medicinal properties of fungi of the genus Pleurotus have attracted great interest due to their therapeutic properties. Polysaccharides synthesized by Pleurotus, including the ß-glucans are considered the main responsible for its therapeutic properties. This study aimed to evaluate the efficacy of polysaccharidic fractions extracted from mycelial biomass of Pleurotus ostreatus DSM 1833 in inhibiting the development of Ehrlich Tumor (ET) and Sarcoma 180 (S-180). FC, FI and FII fractions provided 60.6, 76.5 and 73.6% of ET inhibition, respectively (mean value of about 70%) while FS, FIII-1 and FIII-2 showed no inhibition against ET. FII and FIII-2 resulted in 85.6 and 93.6% (mean value of about 90%) while FIII-1, FC and FS resulted in 54.1 and 0%, respectively, of S-180 inhibition. The yields of the fractions FS, FI, FII, FIII-1 and FIII-2 obtained from P. ostreatus mycelial biomass were 11.6, 1.3, 0.4, 0.65 and 0.35%, respectively. FII fraction (30mg/kg) apparently had no toxic effect on healthy animals, since no difference between the body weights of animals in substance control (SC) and negative control (NC) groups was observed.