Background: Recent in silico and in vitro studies have shown that gastrointestinal endogenous proteins
(GEP) are a source of bioactive peptides. To date, however, the presence of such peptides in the lumen of
the digestive tract has not been demonstrated.
Objective: We investigated the generation of GEP-derived bioactive peptides in the growing pig fed a proteinfree
Methods: Stomach chyme (SC) and jejunal digesta (JD) fractions from 6 growing pigs (two sampling times)
were assessed for their angiotensin-I-converting enzyme (ACE-I; EC 22.214.171.124) inhibition, and antioxidant activity
using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition, ferric reducing antioxidant power (FRAP) and
microsomal lipid peroxidation (MLP) inhibition assays.
Results: Two of the fractions prepared from JD samples inhibited ACE-I and DPPH by 81 (± 2.80)% and 94
(±0.66)%. SC fractions were found to inhibit MLP between 15-39 (±3.52-1.40)%. The study identified over 180
novel peptide sequences that were related to the determined bioactivities, including a porcine serum albuminderived
peptide (FAKTCVADESAENCDKS), corresponding to f(7-23) of the human serum albumin peptide
LVNEVTEFAKTCVADESAENCDKSLHTLF that was previously identified from the digests of the latter GEP.
Conclusion: This study provides the first in vivo evidence for GEP as a source of bioactive peptides. These new
findings help advance our knowledge of the latent bioactive role of GEP-derived peptides in mammalian nutrition
and health and their potential pharmaceutical applications.
Keywords: Angiotensin-I converting enzyme (ACE-I) inhibition, antioxidant peptides, exogenous bioactive peptides, ferric reducing antioxidant
power, gut non-dietary proteins, microsomal lipid peroxidation inhibition, non-dietary proteins, porcine model, serum albumin.
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