15 Blood Pressure-Lowering Peptides Identified from Underutilized Winged Bean Seeds | Research

The takeaway

Researchers identified 15 ACE-inhibitory peptides from winged bean seeds, with the most potent fraction achieving 87.8% ACE inhibition, demonstrating this sustainable tropical crop's potential for producing blood pressure-lowering peptides.

87.8% ACE inhibition from top fraction
The most active winged bean peptide fraction achieved near-complete ACE inhibition, with 15 individual peptides identified and sequenced

What the researchers found

Papain hydrolysis of winged bean seed protein produced ACE-inhibitory fractions. Three key subfractions were identified: F-12-12 (87.8% ACE inhibition, pI 10.0), F-16-6 (77.3% inhibition, pI 6.8), and F-16-2 (50.1% inhibition, pI 3.6). Sequencing identified 11 peptides via database search and 4 via de novo sequencing, totaling 15 unique ACE-inhibitory peptides. All were oligopeptides of 4-15 amino acid residues with molecular weights of 489.9-1656.7 Da (all <2 kDa).

Why it matters

Finding new sustainable sources of bioactive peptides is important for both global nutrition and cardiovascular health. Winged bean grows in tropical regions where hypertension is a major health burden but access to pharmaceutical ACE inhibitors may be limited. Developing winged bean-based functional foods or supplements could provide affordable, locally sourced blood pressure support while promoting cultivation of this underutilized but highly nutritious crop.

How the study worked

Winged bean seeds were enzymatically hydrolyzed with papain. The hydrolysate was separated by reverse-phase HPLC followed by isoelectric focusing. ACE-inhibitory activity was measured for each fraction. Selected active fractions were sequenced using LC-MS/MS. Peptides were identified through database matching and de novo sequencing, with structural analysis confirming ACE-inhibitory properties.

What this study cannot tell us

This is entirely an in vitro study — no cell culture, animal, or human studies were performed. ACE inhibition in a test tube doesn't guarantee blood pressure effects in vivo. The peptides' stability during gastrointestinal digestion and their absorption potential were not tested. Only papain was used as the hydrolysis enzyme; other enzymes might yield different peptides. The winged bean variety and growing conditions could affect results.

How to read the evidence

This is an in vitro analytical chemistry study focused on peptide identification and characterization. While the ACE inhibition data is strong, no biological validation (cell, animal, or human) was performed, representing the earliest stage of bioactive peptide research.

When this study was published

Published in 2025, this study expands the library of plant-derived ACE-inhibitory peptides to include winged bean — a crop with significant untapped potential for tropical food security and health.

The bigger picture

The search for plant-derived ACE-inhibitory peptides has accelerated as interest in functional foods and nutraceuticals grows. While most research focuses on soy, milk, and common grains, underutilized crops like winged bean offer opportunities for both diversifying the food supply and developing novel bioactive peptides. Winged bean is particularly attractive because it has one of the highest protein contents among legumes (30-40%) and thrives in tropical climates where hypertension prevalence is high.

Questions still open

Do the identified winged bean peptides survive gastrointestinal digestion to reach the bloodstream intact?
Could winged bean protein hydrolysates be developed into affordable functional foods for tropical regions with high hypertension rates?
How does the ACE-inhibitory potency of winged bean peptides compare to established sources like milk casein or soybean?

Common questions

What is winged bean and why does it matter?

Winged bean (Psophocarpus tetragonolobus) is a tropical legume sometimes called the 'one species supermarket' because almost every part of the plant is edible and nutritious. It has one of the highest protein contents of any legume (30-40%). Despite this, it's largely underutilized in agriculture. This study shows its protein can be broken down into peptides that block ACE — the same enzyme targeted by blood pressure drugs — adding health value to an already nutritious crop.

Could eating winged bean lower blood pressure?

The raw bean wouldn't deliver these peptides — they're produced by enzymatic breakdown of the protein. A processed product (like a protein hydrolysate supplement or fortified food) would be needed. Even then, in vitro ACE inhibition doesn't guarantee in vivo blood pressure reduction. Human studies are needed. But the high inhibition levels found suggest winged bean protein is a promising source for developing blood pressure-supporting functional foods.

Read the original research

Two-dimensional profiling and peptide sequencing of angiotensin-I converting enzyme (ACE) inhibitory proteolysate from winged bean (Psophopcarpus tetragonolobus) seeds.

Analytical methods : advancing methods and applications, 17(22), 4627-4638

View on PubMed ↗Publisher’s paper ↗

Citation

Chay, Shyan Yea; Brishti, Fatema Hossain; Auwal, Shehu Muhammad; Abdul Kari, Zulhisyam; Roslan, Nurdiyana Aqilah; Wong, Clement Kiing Fook; Saari, Nazamid. (2025). Two-dimensional profiling and peptide sequencing of angiotensin-I converting enzyme (ACE) inhibitory proteolysate from winged bean (Psophopcarpus tetragonolobus) seeds.. Analytical methods : advancing methods and applications, 17(22), 4627-4638. https://doi.org/10.1039/d4ay02073a