Comprehensive utilization of edible mushroom <i>Auricularia auricula</i> waste residue—Extraction, physicochemical properties of melanin and its antioxidant activity

Abstract

In order to promote the comprehensive utilization of the <i>Auricularia auricula</i> waste residue, the extraction process and the physicochemical properties of melanin from <i>A. auricula</i> waste residue were studied. Furthermore, the chemical antioxidant activity of waste residue melanin and its protective effect on cell oxidative injury induced by H₂O₂ were investigated. The results indicated that the ultrasonic-assisted extraction process could be used to extract the melanin from <i>A. auricula</i> waste residue. Melanin had a good solubility in alkali solution and exhibited a certain stability to thermal. There was no significant difference between <i>A. auricula</i> melanin control group and waste residue melanin on ABTS, DPPH, and hydroxyl radical scavenging activity. Waste residue melanin significantly inhibited the cell death caused by H₂O₂, and the cell viability was restored to 98.09 ± 5.97% when the melanin concentration was 1.6 mg/ml. Cell morphology observation confirmed that the melanin ameliorated the morphological changes of cells induced by oxidative stress.