The α-Amylase and α-Glucosidase Inhibitiory Effects and Antioxidant Properties of Native Lactobacilli Strains Isolated from Traditional Fermented Dairy Products

Diabetes is the third leading cause of premature death worldwide due to hyperglycemia and hyperglycemic-induced oxidative stress. The use of lactic acid bacteria (LAB) is one of the new therapeutic strategies to improve diabetes and its complication. Thus, this paper aimed to investigate the anti-hyperglycemic and antioxidant properties of the cell-free extract (CFE) and cell-free supernatant (CFS) obtained from 10 native LAB strains isolated from traditional fermented dairy products. The anti-hyperglycemic activity of LAB strains was evaluated by the α-amylase and α-glucosidase inhibition assay. The antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, hydroxyl, superoxide anion, ferric-reducing, iron chelating, and total antioxidant capacity. Finally, phenolic and flavonoid content of CFS of samples were assessed. The findings showed that Lactobacillus delbrueckii had the higher antidiabetic properties compared to other strains with the highest α-glucosidase inhibitory activity in CFE (25%) and CFS (50%). Other LAB strains showed high antioxidant ability in CFE and CFS. Among them, Lactobacillus paracasei had the highest antioxidant activity. The results showed that the CFS contained phenolic and flavonoid compounds. Finally, the data demonstrated that L. delbrueckii, L. paracasei, Lactobacillus helveticus, and Lactobacillus fermentum could be applied in the production of health-related products, food additives and animal feed.