Jack Bean (Canavalia ensiformis) Tempeh: ACE-Inhibitory Peptide Formation during Absorption in the Small Intestine.

Research background: High blood pressure is the most significant cause of mortality globally. Some fermented foods include ACE-inhibitory peptides that help fight this disease. The ability of fermented jack bean (tempeh) to inhibit ACE during consumption has not been demonstrated yet. This study identified and characterised ACE-inhibitory peptides from jack bean tempeh produced by small intestine absorption using the everted intestinal sac model. Experimental approach: Sequentially, the protein extract of jack bean tempeh and unfermented jack bean was hydrolysed using pepsin-pancreatin for 240 min. The hydrolysed samples were then evaluated for the peptide absorption using three-segmented everted intestinal sacs (duodenum, jejunum and ileum). The peptides absorbed from all intestinal segments were mixed in the small intestine. Results and conclusion: The data showed that both jack bean tempeh and unfermented jack bean had the same peptide absorption pattern, with the highest percentage of peptide absorption in the jejunum, followed by the duodenum and ileum. The absorbed peptides of jack bean tempeh exhibited equally strong activity of ACE inhibition in all intestinal segments, while the unfermented jack bean showed strong activity only in the jejunum. The mixture of the peptides from jack bean tempeh absorbed in the small intestine had higher ACE-inhibitory activity (81.09%) than the unfermented jack bean (72.22%). The peptides produced from jack bean tempeh were identified as pro-drug ACE inhibitors and had the mixed inhibition pattern. The mixture of peptides consisted of seven types of peptides with a molecular mass of 826.86-978.20 Da (DLGKAPIN, GKGRFVYG, PFMRWR, DKDHAEI, LAHLYEPS, KIKHPEVK, and LLRDTCK). Novelty and scientific contribution: This study discovered that consuming jack bean tempeh generated more potent ACE-inhibitory peptides during small intestine absorption than cooked jack beans. Absorbed tempeh peptides have high ACE-inhibitory activity.

In vitro gastrointestinal simulation of tempe prepared from koro kratok (Phaseolus lunatus L.) as an angiotensin-converting enzyme inhibitor.

This study investigated the formation of angiotensin-converting enzyme (ACE) inhibitory peptides from koro kratok beans tempe during gastrointestinal digestion. The absorption of bioactive peptides was also investigated in this study. Koro kratok was fermented by commercial culture including Rhizopus oligosporus for 48 h. Gastrointestinal digestion was simulated sequentially by hydrolysis of tempe protein extract with pepsin and pancreatin for 240 min. The peptide content, degree of hydrolysis, molecular weight distribution, and ACE inhibitory activity were analyzed. The absorption of ACE inhibitory peptides was evaluated using the inverted gut sac of Sprague Dawley rats. Results showed that some amino acids, such as Arg, Lys, Asp, Glu, Phe, and Leu, were predominantly found in tempe. After the hydrolysis process, cooked tempe exhibited the highest ACE inhibitory activity (90.05%). Although the ACE inhibitory activity of nonfermented koro kratok was lower than that of tempe, the increase in its inhibitory activity was too large (23.03%). The ACE inhibitory peptides from tempe showed a predominance of peptides with a molecular weight of < 1 kDa and could inhibit ACE activity by 84.34%. The majority of ACE inhibitory peptides from tempe was absorbed in the jejunum and exhibited an ACE inhibitory activity of 81.59%. Based on these results, it can be concluded that the fermentation and boiling process of koro kratok beans improved the release of ACE inhibitory peptides during the gastrointestinal digestion process and had an impact on its absorption.

Formation of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from Jack Bean (Canavalia ensiformis (L.) DC.) sprout in simulated digestion.

Bean sprouts are potential plant proteins that produce DPP-IV inhibitory peptides. These peptides must be stable and active in the brush border membrane of the small intestine to inhibit DPP-IV. The purpose of this research is to evaluate the DPP-IV inhibitory activity of jack bean sprouts using pepsin-pancreatin during simulated digestion, as well as the absorption of these peptides through the everted gut sac method. The results showed that after 180 min of digestion simulation, the Mw < 1 kDa peptide fraction of jack bean hydrolysate, which germinated for 60 h (HG60), had the highest inhibitory activity. The duodenum absorbs most of the peptides with inhibitory activity of 61.77%, which is slightly lower than activity after digestion (62.19%). These outcomes suggest that the DPP-IV inhibitory activity of HG60 can be maintained after digestion and absorption. Two novel peptides KAVGDPI and QGVVLRP identified after absorption contain crucial amino acids confirming as DPP-IV inhibitor. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01343-9.

Production of Dipeptidyl Peptidase-IV Inhibitory Peptides from Germinated Jack Bean [Canavalia ensiformis (L.) DC.] Flour.

An alternate plant-based protein, jack bean sprout, was explored as a source of bioactive peptides. Germination to increase dipeptidyl peptidase-IV (DPP-IV) inhibitory peptide in jack bean sprout flour has yet to be reported. Therefore, this study aimed to investigate the optimal condition to maximize the content of bioactive peptides with maximum DPP-IV inhibitory activity. The relationship between germination and DPP-IV inhibitory activity was determined by analyzing the proteolytic activity, percentage of degree of hydrolysis (%DH), and peptide content. Peptide samples with the most potent DPP-IV inhibitory activity were subsequently fractionated, identified, and characterized. The 60-h germinated jack bean had the best DPP-IV inhibitory activity (41.57%; half maximal inhibitory concentration=2.24 mg/mL). Proteolytic activity (15.24 unit/g), %DH (11.43%), and peptide content (59.71 mg/g) supported this result. Furthermore, the <1.0 kDa peptide fraction of this sprouted flour had the highest molecular weight (MW) distribution (32.60%) and DPP-IV inhibitory activity (71.99%). Peptide sequences identified from MW <1.0 and 1.0∼3.5 kDa peptide fractions had valine, leucine, isoleucine, glycine, and tryptophan at the N-terminal and also had alanine at the penultimate N-terminal, verifying their presence as DPP-IV inhibitors. Furthermore, peptide sequences generated exhibited other biological activities, including angiotensin-converting enzyme, renin, and α-glucosidase inhibitors.

Impact of Gastrointestinal Digestion Simulation on the Formation of Angiotensin-I-Converting Enzyme Inhibitory (ACE-I) Peptides from Germinated Lamtoro Gung Flour.

The germination of lamtoro gung has been shown to increase the angiotensin-I-converting enzyme inhibitory (ACE-I) activity in previous studies. The 48 h germinated flour had the highest ACE-I activity. Administration of the gastrointestinal digestion (GID) simulation with commercial enzymes was expected to increase the ACE-I activity. However, the GID simulation to increase ACE-I in the germinated lamtoro gung flour has not been found. Therefore, this study aimed to evaluate the GID simulation of ACE-I peptides in sprouted lamtoro gung flour. This study also identified and characterised the peptide with the ACE-I activity. The GID simulation was performed using commercial pepsin (pH 2) and pancreatin (pH 7.5). Both simulations occurred at 37 °C for 240 min. The degree of hydrolysis, peptide concentration, and ACE-I activity was analysed. Samples with the highest ACE-I activity were then fractionated and identified, to determine the peptide responsible for the ACE-I activity. The 180 min GID simulation in the test sample showed the highest ACE-I activity (89.70%). This result was supported by an increased degree of hydrolysis (DH) and peptide concentrations throughout the GID simulation. The <1 kDa peptide fraction had the highest inhibitory activity and had the most elevated peptide portion (54.69%). Peptide sequences containing crucial amino acids were found in the <1 kDa peptide fraction. PRPPKPP, PPPPPGARAP, and PFPPSNPPP had proline in the C and N terminal residues. The peptides obtained also had other biological activities, such as a DPP IV inhibitor, an alpha-glucosidase inhibitor, and antioxidative activity. Based on the toxicity prediction, those peptides are non-toxic and safe to consume.

Bioactive Peptide Tempe Made from Mucuna pruriens (L) DC as an Inhibitor of Angiotensin-I-Converting Enzyme (ACE) in a Digestion Simulation.

Mucuna pruriens (L) DC tempe is a food that functions as an inhibitor of the angiotensin-I-converting enzyme (ACE). The purpose of this research was to study the activity of M. pruriens tempe peptides during the digestive process in vitro with pepsin-pancreatin, and absorption of peptides in the small intestine using the inverted intestinal sac method. Our results show that M. pruriens had the highest ACE-inhibiting activity after digestion in vitro after fermentation for 72 h (F72). F72 peptide absorption (%) and ACE-inhibitory activity of the absorbed peptides did not significantly differ between the different segments of the small intestine (duodenum, jejunum, and ileum). These results demonstrate that F72 tempe maintains ACE-inhibitory activity in each segment of the small intestine after both digestion and absorption.