Exploring the antioxidant, antidiabetic, and antibacterial potential of postbiotic compounds derived from Lactiplantibacillus plantarum O7S1.

Probiotic bacteria are distinguished by their ability to produce various functional postbiotic metabolites. Therefore, this study aimed to explore the in vitro antioxidant, antidiabetic, and antibacterial properties of two postbiotics generated by Lactiplantibacillus plantarum O7S1 (Lpb. plantarum O7S1) during the fermentation process: cell-free supernatant (CFS) and exopolysaccharides (EPS). The antioxidant potential of these postbiotics was assessed using various radical scavenging assays and ferric-reducing antioxidant potential. The antidiabetic activity was evaluated through α-amylase inhibitory assays, while antibacterial activity was determined using agar well diffusion assays. The results of the present study revealed that CFS exhibited significant antioxidant and antidiabetic efficacy in contrast to EPS (P < 0.001). Specifically, CFS displayed remarkable scavenging ability against DPPH, hydroxyl, and superoxide radicals, with inhibition rates of 88.78, 78.91, and 34.85%, respectively, while EPS showed comparatively lower inhibition rates. Additionally, CFS demonstrated higher reducing activity (0.30 optical density units at 700 nm) and potent α-amylase inhibitory activity (95.87%) compared to EPS (67.17%) (P < 0.001). The agar well diffusion assay reported that CFS showed significant antimicrobial activity against both Gram-positive and Gram-negative pathogens, while no activity was observed with EPS. Furthermore, carbohydrate fermentation analysis indicated the strain's ability to metabolize various carbohydrates and their derivatives, potentially enhancing digestive health. These findings suggest that both CFS and EPS exhibit promising hypoglycemic, antioxidant, and antibacterial properties, making them potential candidates for incorporation into functional foods and pharmaceuticals aimed at preventing oxidative damage, diabetes, and pathogenic bacterial infections.