Abstract
Fermented milk (FM) is well-known to confer health-promoting benefits, particularly for managing chronic metabolic diseases. However, the specific cholesterol esterase (CE) inhibitory activities of FM produced from different animal milk sources have not been extensively explored. This study for the first time investigates the CE inhibition potential of FM derived from bovine (F_BM), camel (F_CM), sheep (F_SM), and goat milk (F_GM), each fermented with five different probiotic strains and stored for 14 days under refrigeration. Further, peptides identification was performed and in silico approaches were used to dock potent peptides with CE enzyme (PDB: 1AQL) to decipher mechanism of enzyme inhibition. Comprehensive approach of this study combined CE inhibition assays, peptide identification, and in silico molecular docking with the CE enzyme (PDB: 1AQL) to elucidate mechanisms underlying enzyme inhibition. Upon fermentation improvements in CE-inhibition (lower IC(50) values) were observed compared to non-fermented counterparts. Moreover, the CE-inhibition potency of the FM varies significantly among the milk types and probiotic strain (p < 0.05). Regardless of probiotic strains, CE-inhibition was more evident for F_GM followed by F_CM. Peptide sequencing and molecular docking studies revealed APSFSDIPNPIGSENSEKTTMPLW from F_BM showed potent binding to CE's active site, while peptides from F_CM, F_SM, and F_GM showed indirect CE-inhibitory mechanisms. These findings suggest potential anti-hypercholesteremic effects of bovine and non-bovine fermented milk, indicating their potential use in developing novel dairy products with hypolipidemic activities.