The influence of solvent nature on the extraction yield of Pleurotus pulmonarius, Pleurotus floridanus and Pleurotus sajor-caju and study of the effects of extract mixtures on oxidative stress
Keywords:Extraction yield, antioxidant potential, oxidative stress, edible mushrooms, pleurotus spp.
AbstractOxidative stress plays an important role in the aetiology and pathogenesis of many chronic diseases. Edible mushrooms, especially Pleurotus spp., are considered to be a natural source of potential antioxidants. This work investigated the influence of solvent nature on the extraction yield of Pleurotus pulmonarius, Pleurotus floridanus and Pleurotus sajor-caju and the influence of extract mixture concentrations on oxidative stress. Extracts from each mushroom species and mixtures (1w:1w:1w) were produced by macerating the powders (1w:5v) in different solvents: distilled water, ethanol, hexane, ethyl acetate and dichloromethane. The extraction yield was then determined and the antioxidant activity was evaluated for the extracts and formulations, with ascorbic acid used as a standard. Based on the best yield and antioxidant activity in vitro, the aqueous extract mixture was used for acute toxicity testing (at 2000 mg/kg BW), and its effects at 250 and 500 mg/kg BW over 14 days on oxidative stress induced in vivo by lead acetate (35 mg/kg BW every two days) were compared. Ascorbic acid was used as a reference. Oxidative stress markers were assessed in serum and homogenized tissue. We found that water had the best yield (66.32% for P. pulmonarius, 68.56% for P. floridanus and 65.40% for P. sajor-caju), followed by the ethanol, ethyl acetate, dichloromethane and hexane extracts. In addition, all extracts and formulations had significant ferric reducing antioxidant power at C = 1 mg/ml (62.59–546.67 mg AAE/g), good scavenging activity as assessed by the DPPH free radical assay at C = 25 mg/ml (63.08– 78.52%) and significant polyphenol content at C = 100 mg/ml (1.69–26.50 mg CE/g) with the best results seen with the aqueous extracts. The aqueous extract mixture showed no particular signs of toxicity. After lead exposure, significant increases were observed with respect to serum transaminase activity and creatinine and urea levels, but a decrease in total protein levels was found. In addition, a significant increase in malondialdehyde levels but a decrease in reduced glutathione levels and superoxide dismutase, catalase and total antioxidant capacity was noted in the serum, liver and kidneys. Treatment with the mixture brought about a significant amelioration in terms of antioxidant parameters, with the greatest effect seen with a dose of 500 mg/kg BW, as well as with the ascorbic acid used as a reference. The results here suggest that these mushrooms, due to their antioxidant potential, are beneficial for health and could be useful for the production of medicinal products and nutraceuticals.