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This work studied the cell transport of peptidase-generated peptides from cowpea bean proteins and their effects on mRNA expression of cholesterol-related genes in intestinal and liver cells. The ≤3 kDa hydrolysate was obtained and incubated with Caco-2 intestinal cells using Transwell® plates. HepG2 liver cells were incubated with synthetic analogues of peptides (MELNAVSVVHS and MELNAVSVVSH) identified by “ de novo ” peptide sequencing in the Caco-2 monolayer permeates. The mRNA expression of NPC1L1 , ABCA1 and ABCG1 was measured in Caco-2 cells, in the presence or absence of ≤3 kDa hydrolysate and the expression of HMGCR , SREBP2 , LXRα , AMPK1 , was determined in the HepG2 cells in the presence or absence of synthetic peptides. Exposure of Caco-2 cells to cowpea ≤3 kDa hydrolysate (2.5 and 5 mg/mL) increased ABCG1 expression at 6 h and 12 h. SREBP2 , HMGCR and LDLR mRNA levels were reduced in HepG2 cells after 24 h of treatment with MELNAVSVVHS peptide (50 μM and 100 μM). These results suggest that MELNAVSVVHS peptide is able to cross intestinal barrier and to modulate genes involved in cholesterol homeostasis. [ABSTRACT FROM AUTHOR]

This study aimed to assess the hypocholesterolemic activity of peptides obtained by in vitro simulated human digestion of cowpea bean proteins; moreover, we have screened the bioactive peptides through chromatographic separation by RP-HPLC of the 3 kDa molecular mass cut-off fraction of hydrolyzed isolated cowpea protein. Micellar solubility of cholesterol was measured after adding 35 μg mL − 1 of each fraction on in vitro prepared intestine-like micelles. The inhibiting activity of each fraction (50 μg mL − 1 ) also was tested on the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase). The whole hydrolysate was analyzed by ‘de novo’ mass spectrometry peptide sequencing (RP-HPLC-MS 2 ) and the top score candidate peptide sequences were further analyzed by computational modeling. All collected fractions inhibited the initial HMG-CoA reductase activity by 47.8 to 57.1%. They also reduced cholesterol micellar solubilization, with fraction 1 being the most effective (71.7%). The peptide conserved domains may interact with the phosphatidylcholine added in the reaction of the cholesterol micelles. According with a computational prediction, the only peptide able to bind significantly the HMG-CoA reductase was GCTLN. This is the first report of peptide fractions from cowpea bean protein released by human digestion enzymes (pepsin followed by pancreatin) assigned to its cholesterol-lowering effect. These routes may define their action in lipid metabolism. [ABSTRACT FROM AUTHOR]

The objective of this work was to determine the impact of germination of cowpea ( Vigna unguiculata ), combined with enzymatic hydrolysis on the generation of bioactive peptides with dipeptidyl peptidase IV (DPP-IV) inhibition activity and antioxidant capacity. Germination (25 °C, up to 48 h) and alcalase hydrolysis (up to 4 h) significantly increased antioxidant capacity of cowpea proteins from 293.4 to 993.7 μmol TE/g soluble protein (SP). The non-germinated and 1 h alcalase hydrolysates showed the highest DPP-IV inhibition (IC 50 = 0.58 mg SP/mL), after in vitro simulated gastrointestinal digestion. Selected peptides in the hydrolysates were analyzed by computational modeling. The TTAGLLE peptide interacted with S2 (GLU205, GLU206) and S3 (SER209, ARG358, PHE357) pockets of DPP-IV, and it is expected to inhibit DPP-IV by blocking its active site. Cowpea short time germination (24 h) and alcalase protein hydrolysis (1 h) can be used to produce ingredients with high antioxidant capacity and DPP-IV inhibition. [ABSTRACT FROM AUTHOR]