Two peptides engineered from a jujube fruit ACE inhibitor — WALVAP and WPLVAP — gained 6-fold stronger DPP-IV inhibitory activity while retaining blood pressure-lowering properties, and improved glucose metabolism in mice.
6.25× stronger DPP-IV inhibitionRational modification of a jujube fruit peptide dramatically enhanced blood sugar-lowering activity while retaining the original blood pressure-lowering function
What the researchers found
WALVAP demonstrated 6.25-fold higher DPP-IV inhibitory activity than the parent peptide KALVAP (IC₅₀: 360.39 vs 1,372.57 μmol/L in Caco-2 cells), while WPLVAP showed 3.52-fold improvement. Both peptides retained the ACE-inhibitory (blood pressure-lowering) activity of the original KALVAP.
In oral glucose tolerance tests in C57BL/6 mice, both WALVAP and WPLVAP significantly improved glucose metabolism by promoting secretion of insulin (11.13% and 11.61% increase), GLP-1 (11.12% and 11.61% increase), and GIP (7.58% and 7.66% increase). Molecular dynamics simulations revealed that both peptides inhibit DPP-IV primarily through interactions with key binding site residues Glu205, Trp629, Glu206, Arg125, and Arg429.
Why it matters
Hypertension and type 2 diabetes frequently coexist, and patients often take multiple medications for each condition. A single peptide that inhibits both ACE (lowering blood pressure) and DPP-IV (improving blood sugar) could simplify treatment. This study demonstrates that rational peptide design can convert a single-target food-derived peptide into a dual-action candidate, providing a blueprint for developing multifunctional peptide therapeutics from natural sources.
How the study worked
Starting from the jujube-derived ACE inhibitory peptide KALVAP, researchers designed nine modified peptides incorporating structural features known to enhance DPP-IV inhibition. Candidates were screened through molecular docking simulations, then validated with in vitro DPP-IV inhibition assays and Caco-2 cell experiments. The top two candidates (WALVAP and WPLVAP) were tested in vivo using oral glucose tolerance tests in C57BL/6 mice, measuring insulin, GLP-1, and GIP secretion. Molecular dynamics simulations elucidated the binding mechanism.
What this study cannot tell us
The in vivo effects were tested only in normal mice with an oral glucose tolerance test, not in diabetic or hypertensive animal models where the dual activity would be most relevant. The peptides were tested acutely, and chronic effects on blood pressure and blood sugar are unknown. Oral bioavailability — critical for food-derived peptides — was not directly measured; peptides are typically degraded during digestion. The incretin increases (~11%) are modest and may not be clinically meaningful. Manufacturing feasibility for clinical use was not addressed.
How to read the evidence
This is a preclinical peptide design study combining computational modeling, in vitro assays, cell-based experiments, and in vivo mouse testing. The multi-method approach strengthens the findings, but the use of normal mice (not disease models), acute dosing, and unknown oral bioavailability limit the translational significance.
When this study was published
Published in 2026, this is a very recent study reflecting the latest approaches in rational bioactive peptide design for metabolic disease.
The bigger picture
The development of multi-target peptide drugs is an emerging strategy in pharmaceutical design. Current clinical DPP-IV inhibitors (sitagliptin, saxagliptin) are small molecules, not peptides, and ACE inhibitors (lisinopril, enalapril) are separate drugs. Creating a single peptide with both activities from a food-derived scaffold is innovative because food peptides are generally well-tolerated and the design approach could be applied to other therapeutic combinations.
Questions still open
- Would WALVAP and WPLVAP maintain their dual activity in diabetic and hypertensive animal models?
- Can these peptides survive gastrointestinal digestion to reach therapeutic concentrations in the blood?
- Could the rational design approach used here be applied to create triple-activity peptides targeting ACE, DPP-IV, and other metabolic targets simultaneously?
Common questions
What is DPP-IV and why does inhibiting it lower blood sugar?
Can food-derived peptides really work as medicines?
Read the original research
Design and experimental verification of novel angiotensin-converting enzyme and dipeptidyl peptidase IV inhibitory peptides from Ziziphus jujuba peptide KALVAP.
Journal of the science of food and agriculture, 106(1), 249-259
Citation
Wen, Huan; Lan, Jing; Dang, Kuo; Wang, Yanli; Pan, Daodong; Gao, Xinchang; Dang, Yali. (2026). Design and experimental verification of novel angiotensin-converting enzyme and dipeptidyl peptidase IV inhibitory peptides from Ziziphus jujuba peptide KALVAP.. Journal of the science of food and agriculture, 106(1), 249-259. https://doi.org/10.1002/jsfa.70156