Antioxidant and hypoglycemic effects of Diospyros lotus fruit fermented with Microbacterium flavum and Lactobacillus plantarum

Diospyros lotus , a member of the Ebenaceae family, has long been used as a traditional sedative in China. In this study, the antioxidant and hypoglycemic effects of non-fermented and microorganism-fermented D . lotus were explored. The total phenolic and vitamin C contents of microorganism-fermented D . lotus for 24–72 h were less than those of non-fermented. High-performance liquid chromatography showed that the tannic, catechinic, and ellagic acid contents increased significantly upon fermentation for 24 h. D . lotus fermented with Microbacterium flavum for 24 h exhibited the highest DPPH radical scavenging activity (IC 50  = 4.18 μg mL −1 ), and the highest ABTS radical scavenging activity was exhibited at 72 h of fermentation (IC 50  = 29.18 μg mL −1 ). The anti-α-glucosidase activity of fermented D . lotus was higher (2.06–4.73-fold) than that of non-fermented one. Thus, fermented D . lotus is a useful source of natural antioxidants, and a valuable food, exhibiting antioxidant and hypoglycemic properties.