Unlocking novel biopeptides hidden in Camellia seed cake fermented by Bacillus subtilis through in silico and cellular model approaches.

In this study, Bacillus subtilis was used to ferment the CSC and produce hydrolysates (CSCH), from which novel bioactive peptides were identified. The ultrafiltration fraction of CSCH under 3 kDa (CSCH-3) revealed the most efficient in vitro antioxidant and anti-tyrosinase activity. The peptide profile of CSCH-3 was further characterized using LC-MS/MS, and novel biopeptides were screened through in silico analysis and molecular docking methods. Four peptides (LPFR, WGFKPK, PFDLR, and FPGEL) were recognized as the most promising antioxidant and anti-tyrosinase peptides based on their better binding affinities (< 5 kcal/mol) with the tested receptors. Cell antioxidant assay revealed that the four peptides exhibited significant (P < 0.05) antioxidant activity against AAPH-induced oxidative damage. Meanwhile, B16F10 cell model tests revealed that tyrosinase activity was significantly (P < 0.05) inhibited by LPFR (44.62 %), WGFKPK (32.12 %), PFDLR (34.06 %), and FPGEL (33.66 %) compared to the control. The docking results suggested that the four peptides were tightly bound to antioxidant related receptors (DPPH, ABTS, CAT, SOD, and Keap1) and tyrosinase, suggesting that each peptide could exhibit multiple bioactivities via various structure-activity linkages.