Bioassay guided fractionation of Pleurotuscystdious to investigate the antimicrobial activity, anti-hypercholesterolemic effects, antioxidant and cytotoxic properties.

Abstract

Mushrooms have recently become attractive as a source with various medicinal values. Separation and isolation of compounds/fractions of P l e u r o t u s c y s t i d i o s u s mushroom, responsible for antimicrobial activity, anti-hypercholesterolemic activity, antioxidative activity and cytotoxicity against H e p - 2 cancer cells were examined during this study. Acetone (A), dichloromethane (D) and hexane (H) extracts of P . c y s t i d i o s u s were obtained by a sequential extraction method and analyzed for antibacterial activity. All three extracts (20,000 ppm) did not show antibacterial activity against E . c o l i , S t a p h y l o c o c c u s or K l e b s i e l l a . Antifungal assay was also carried out with bioassay guided fractionation method and all the test solutions were in the concentration of 20, 000 ppm. Antifungal activity of acetone extract against R. solani, C u r v u l a r i a spp., A l t e r n a r i a spp., C. a c u t a t u m and C. g l o e o s p o r i o i d e s resulted in the highest inhibitory activity (12%) against C. g l o e o s p o r i o i d e s . Antifungal assay guided fractionation of acetone extract (A) resulted in four fractions, A l , A2, A3 and A4. Fractions A2 and A4 were further separated as those two fractions showed 22% and 17% inhibitory activities. Out of the four fractions A2-1, A2-2, A2-3 and A2-4, fraction A2-3 showed the highest inhibitory (26%) activity. Inhibition of C. g l o e o s p o r i o i d e s by the three fractions A4-1, A4-2 and A4-3 was not satisfactory. Further separation of fraction A2-3 resulted the isolation of 3p,5a,6|3- trihydroxyergosta-7,22-diene with 41% inhibitory activity. Two mushroom species (X and Y) were used to study blood cholesterol lowering properties using rat models. The groups treated with each freeze dried mushroom powder (lg/kg body weight) decreased blood cholesterol and LDL cholesterol significantly. The cholesterol lowering property of mushroom X was slightly higher than that of mushroom Y. The increased dose of 2g/kg body weight of mushroom X freeze dried powder decreased blood cholesterol level more than that of the rats treated with the dose of lg/kg body weight of mushroom X . The acetone extract (lg/kg body weight) and dichloromethane extract (0.5g/kg body weight) did not show significant decrease in hypocholesterolemic activity. Tablets produced using the freeze dried powder of mushroom X also showed significant cholesterol lowering properties. Acetone and dichloromethane extracts were further fractionated and ' H & 1 3C N M R spectra were obtained and compared with those of lovastatin separated from a commercially available tablet used for lowering of cholesterol. The NMR spectra did not match. Literature reveals that dietary fiber can lower blood cholesterol levels. High fiber content of mushroom X and Y (5.7% and 5.0% respectively) may also play a role in lowering blood cholesterol levels. Estimation of the cholesterol content in rat fecal matter proved that freeze dried powder of mushroom X increases the cholesterol excretion. All water soluble extract/fractions of P . c y s t i d i o s u s A, A4-1, A4-2 and A4-3 showed significant antioxidant activity in DPPH radical assay. Fraction A4-2 and A4-3 showed higher NO radical scavenging activities. The respective IC50 values obtained for DPPH radical scavenging assay were 1.12, 1.13, 0.87, 0.81 and 0.82 mg/mL. IC50 values of nitric oxide radical scavenging assay were 4.81, 3.82, 5.38, 0.87 and 0.61 mg/mL. Fraction A4-2 and A4-3 also showed higher antiproliferative and cytotoxic activities against H e p - 2 cancer cells, in MTT and L D H assays. Cell morphological changes observed microscopically gave further evidence that those two fractions have cytotoxic activities. It is concluded that P . c y s t i d i o s u s shows antifungal, cholesterol lowering, antioxidant and cytotoxic activities.