Anti-leukemic and immunomodulatory effects of fungal metabolites of Pleurotus pulmonarius and Pleurotus ostreatus on benzene-induced leukemia in Wister rats

BACKGROUND The use of natural bioactive compounds in conventional chemotherapy is a new direction in cancer treatment that is gaining more research attention recently. Bioactive polysaccharides and polysaccharide-protein complexes from some fungi (edible mushrooms) have been identified as sources of effective and non-toxic antineoplastic agents. Selected oyster mushrooms (Pleurotus pulmonarius and P. ostreatus being local [Nigeria] and exotic strains, respectively) were cultured on a novel medium of yeast extract supplemented with an ethanolic extract of Annona senegalensis, and the antileukemic potential of their metabolites was studied. METHODS Leukemia was successfully induced in Wister rats by intravenous injection (0.2 mL) of a benzene solution every 2 days for 3 consecutive weeks. The aqueous solution of fungal metabolites (20 mg/mL) produced by submerged fermentation was orally administered (0.2 mL) before, during, and after leukemia induction. Leukemia burden was assessed by comparing the hematological parameters at baseline and after leukemia induction. The immunomodulatory potential of the metabolites was assessed by using a phagocytic assay (carbon clearance method). The ability to enhance leukopoiesis was assessed by using the total leukocyte count. RESULTS Leukemia induction resulted in significant anemia indices and leukocytosis (P<0.05) in the experimental rats. Both metabolites equally enhanced leukopoiesis and demonstrated phagocytic actions; P. ostreatus activity was significantly higher than that of P. pulmonarius (P<0.05). CONCLUSION The metabolites exhibited profound antileukemic potential by suppressing leukemia and demonstrating immunotherapeutic activities on animals after oral administration in various experimental groups.