Antioxidant and Antibacterial Activities of Secondary Metabolites from Microporus xanthopus (Fr.) Kuntze (Polypore) Collected from the Wild in Lagos, Nigeria

Abstract

The secondary metabolites in medicinal mushrooms are responsible for their activity against infectious diseases, cancer, diabetes, and diseases caused by presence of free radicals in the body. Microporus xanthopus a polypore medicinal mushroom was collected from the wild in Lagos Nigeria and identified using standard manuals and oligosaccharides, polysaccharide and polyphenols extracted from its tissues were investigated for antibacterial and antioxidant activities. M. xanthopus oligosaccharides were extracted with neutral and acid detergents and hydrolysis with concentrated H₂SO₄. Polysaccharides and polyphenols extracted with hot water and acidified methanol, respectively. Concentrations of oligosaccharides, polysaccharides and polyphenols were determined with the total carbohydrate and total phenolic quantification assay kits, respectively. The antioxidant activities of the extractsnvestigated using the DPPH Radical Scavenging Assay and Trolox Antioxidant Equivalent Capacity (TEAC) Assay in In-Vitro experiments in 96-well microtiter plates. The antibacterial effect of the extracts was determined with broth microdilution assay using human pathogenic bacteria (Escherichia coli (0157:H7) and Staphylococcus aureus ATCC^®700698 (MRSA). Oligosaccharides showed the highest DPPH radical scavenging activity (86%) with half maximal effective (EC₅₀) of 16.46µg/mL. The highest TEAC value (1.18µM TE/g) was recorded in the oligosaccharide extract and the least TEAC value (0.39µM TE/g) was in the polyphenol extract. The most potent antimicrobial agent was the oligosaccharide extract with IC₅₀ of 44.64 µg/mL and 40.08 µg/mL for E. coli and S. aureus, respectively. Oligosaccharide extracts were more active than the polyphenol and polysaccharide extracts. M. xanthopus oligosaccharides can be developed as potential new dietary supplements with antioxidant and antibacterial activities.