Antiobesogenic effect of hydrolysates and peptide fractions of porcine collagen after in vitro gastrointestinal digestion

The present study evaluated the angiotensin-converting enzyme inhibitory activity (ACEi) of a porcine skin collagen hydrolysate (PSCH) and its peptide fractions before and after a simulation of gastrointestinal digestion and their ability to reduce lipid accumulation in adipocytes (LAA). Before digestion, peptide fractions <1 kDa (PF4) had the highest (p < 0.05) ACEia (85.45 %), followed by PSCH (53.54 %). Post-digestion, PF4 (IC50: 124.49 μg/mL) decreased its activity; thus, DPF4 (digested PF4) had an ACE IC50 of 204.56 μg/mL, while fraction <1 kDa from digested hydrolysate (FDH) showed the lowest activity (IC50: 313.81 μg/mL). Peptides were identified by LC-MS/MS and homology database search and aligned to peptides widely recognized as ACE inhibitors. Nine peptides were identified as potential ACE inhibitors through docking with the active site cavity of this enzyme (mainly GAXGPXGPQ and GPPGPA), and interaction with Zn (II). Subsequently, adding 600 μg/mL of FDH in preadipocytes reduced 71 % LAA, while DPF4 was less effective (45.5 % reduction). The addition of digested peptide fractions into differentiated adipocytes had a similar (p > 0.05) reduction of LAA of 22-39 %. Therefore, regardless of their differences as ACE inhibitors, digested FDH and DPF4 have a similar potential as anti-obesogenic adjuvants. SIGNIFICANCE: In this study, we evaluated the angiotensin-converting enzyme inhibitory activity of a porcine skin collagen hydrolysate and its peptide fractions before and after a simulation of gastrointestinal digestion and their ability to reduce lipid accumulation in adipocytes. Peptides were identified by LC-MS/MS and homology database search and aligned to peptides widely recognized as ACE inhibitors. Nine peptides were identified as potential ACE inhibitors through docking with the active site cavity of this enzyme (mainly GAXGPXGPQ and GPPGPA), and interaction with Zn (II). Subsequently, adding digested peptide fractions into differentiated adipocytes resulted in a reduction of lipid accumulation in adipocytes.