Antioxidant activities of novel peptides from Limosilactobacillus reuteri fermented brown rice: A combined in vitro and in silico study

Oxidative stress is known to cause cell apoptosis, tissue damage, and pathological changes in the body, but antioxidant peptides are renowned radical scavengers. This study investigated the antioxidative and protective effect of six novel peptides obtained after microbial fermentation of brown rice. The selected peptides (MW ≤ 8 KDa), namely AVPYPQ (P1), ILTAV (P2), LGDVIGVP (P3), NPIFDYVLLP (P4), VAPFPEV (P5), and VLPVPK (P6) exhibited strong antioxidant potential against in vitro radicals with IC₅₀ values for DPPH (5.12 ± 0.9–12.54 ± 0.6 µg/ml), ABTS (5.97 ± 0.2–14.20 ± 1.5 µg/ml), FRAP (4.98 ± 2.2–12.19 ± 0.8 µg/ml) and PSC (9.71 ± 0.5–17.84 ± 1.3 µg/ml),respectively. Additionally, these peptides reduced ROS concentrations in Caco-2 cells treated with hydrogen peroxide. In silico studies indicated all six peptides had a higher binding score for the Keap1-Kelch domain than TX6, a potential Keap1 reference ligand. These findings suggest peptides derived from fermented brown rice might be functional components in foods.