Phenolic Antioxidants of Auricularia Species and Their Inhibitory Effects on α-Amylase, α-Glucosidase and Acetylcholine Esterase Activities

Auricularia is the genus of an edible jelly fungus known for its high nutritional value and good taste. In this study, the phenolic contents and in vitro bioactivities of four Auricularia species were investigated. The total phenolic contents ranged from 3.5 to 20.1 μmol gallic acid equivalents/g. Gallic acid, chlorogenic acid and rutin were the predominant phenolic acids present in the soluble fractions of the four species of Auricularia. Particularly, we identified gallic acid and rutin in A. cornea, gallic acid in A. heimuer and selenium-rich A. cornea var. Li, and chlorogenic acid in A. cornea var. Li. In addition, selenium-rich A. cornea var. Li. showed antioxidant properties including inhibitory activity against ABTS, free radical scavenging capacity and lipid peroxidation resistance. The selenium-rich A. cornea var. Li showed superior inhibitory activities toward α-amylase and acetylcholine esterase (IC50 311.7 and 388.6 μg/mL, respectively) compared to other three Auricularia cultivars. The A. cornea var. Li (IC50, 271.4 μg/mL) displayed strong inhibition towards α-glucosidase. The results suggest that a submerged culture of Auricula is an effective method to produce total phenolics which could potentially be used as a natural antioxidant in the food and pharmaceutical industries.