Antimicrobial and antineoplasic activity of Pleurotus ostreatus.

The objectives of this work were to evaluate the antimicrobial and antineoplasic activity of Pleurotus ostreatus DSM 1833. To study the antimicrobial activity, the following extracts were prepared: water infusion of the fresh fruiting bodies (B1), dehydrated fruiting bodies (B2), fresh mycelium (M1), and dehydrated mycelium (M2). Polysaccharides from the fresh mycelium were also obtained by water infusion followed by ethanol treatment (EP). The extracts were tested against Candida albicans, Escherichia coli, and Bacillus subtilis. To investigate the antineoplasic effect of P. ostreatus, the culture broth in natura, the extract from the culture broth (ECB), and the extract from the fruiting bodies were tested in female Swiss albino mice inoculated with the Ehrlich ascitic tumor (EAT). B1, B2, and M1 showed more than 50.0% inhibition against C. albicans. M2 presented a high degree of inhibition against E. coli (87.5%) and B. subtilis (57.5%), while EP was not effective. All the tested substances inhibited the development of EAT at levels near 70% when injected intraperitoneally in mice. The highest tumor inhibition (76%) was achieved for the treatment with ECB. The intragastric treatment did not promote any reduction in tumor cell development, independent of the test substance.