Extraction Optimization by Experimental Design of Bioactives from Pleurotus ostreatus and Evaluation of Antioxidant and Antimicrobial Activities

Oyster mushroom (Pleurotus ostreatus) has gained in the last years increasing attention due to its richness in bioactive metabolites with health properties, making this variety an attractive candidate for promising developments in nutraceutical and cosmeceutical fields. According to the conditions planned by the experimental design approach, the ultrasound-assisted extraction of the phenol fraction from P. ostreatus was performed by evaluating the influence of critical variables (solvent, solvent/solid ratio, time, temperature) on total phenol content and antioxidant activity. The results of the optimization showed that a more performing extraction can be obtained with the highest values of solvent/solid ratio and water % in ethanol. The optimal extraction conditions were applied to four P. ostreatus samples, differing for geographical origin and growth substrate. The hydroalcoholic extracts were characterized in terms of total phenol content, and in vitro antioxidant and antimicrobial activities and interesting correlations were found among them. The obtained results highlighted significant differences for the antioxidant and antimicrobial activities for P. ostreatus samples grown on different substrates and geographical areas. The investigation on biological activity of edible mushroom extracts has a high relevance since it has a positive impact on the nutritional and health properties.