The novel fish-derived peptide LEPWR from Pacific saury inhibits ACE (IC50: 99.5 μM) via mixed competitive inhibition, crosses the intestinal barrier through tight junctions (Papp: 3.56×10⁻⁶ cm/s), and the parent hydrolysate lowers blood pressure in spontaneously hypertensive rats.
Papp: 3.56×10⁻⁶ cm/sLEPWR's intestinal permeability — moderate absorption via paracellular transport through tight junctions, combined with confirmed in vivo blood pressure reduction in hypertensive rats
What the researchers found
The Pacific saury peptide LEPWR inhibits ACE (IC50: 99.5 μM) through mixed competitive inhibition with 6 hydrogen bonds, and demonstrates intestinal absorption via paracellular transport (Papp: 3.56×10⁻⁶ cm/s) through Caco-2 monolayers.
Why it matters
This study goes beyond most food peptide research by demonstrating both in vivo blood pressure reduction AND intestinal absorption — the two critical requirements for a food-derived peptide to actually work as an oral antihypertensive. The paracellular transport route provides a mechanistic explanation for how small peptides from food can reach the bloodstream.
The numbers in context
Novel peptide sequences identified; antihypertensive effect confirmed in SHR model; transport routes characterized.
How the study worked
Bioactivity-guided purification of Pacific saury hydrolysates via ultrafiltration, Sephadex G-25, and RP-HPLC. Antihypertensive effect confirmed in SHR model. Peptide identification by Q-Orbitrap-MS/MS. Molecular docking for binding analysis. Caco-2 monolayer transport studies with apparent permeability measurement and transport route characterization.
Who was studied
Spontaneously hypertensive rats (SHR model)
What this study cannot tell us
The SHR blood pressure reduction was shown for the crude hydrolysate fraction, not purified LEPWR specifically. The IC50 of 99.5 μM is moderate — higher doses would be needed. Caco-2 monolayers are a model, not real intestine. Long-term antihypertensive effect and dose-response relationship in animals not established. Papp of 3.56×10⁻⁶ cm/s indicates moderate absorption, not high.
How to read the evidence
Preliminary-to-moderate — combines in vitro ACE inhibition, intestinal transport studies, and in vivo blood pressure reduction in an animal model (SHRs). Stronger evidence than most food peptide studies, but human data is lacking.
When this study was published
Published in 2024, part of the active research area of fish-derived antihypertensive peptides with absorption and in vivo validation.
The bigger picture
This is one of a handful of studies that demonstrate the full pipeline for food-derived ACE inhibitors: identification, in vitro potency, intestinal absorption, and in vivo blood pressure effect. The intestinal transport data via tight junctions is particularly valuable, as it explains the mechanism by which small food peptides bypass the intestinal barrier. Pacific saury joins tuna, mackerel, and other fish as validated sources of bioactive antihypertensive peptides.
Questions still open
- Does purified LEPWR alone lower blood pressure in SHRs, or is the effect dependent on the peptide mixture?
- What dose of Pacific saury hydrolysate would be needed for clinically meaningful blood pressure reduction in humans?
- Can the paracellular transport route be enhanced to improve LEPWR bioavailability?
Common questions
How does this fish peptide actually get from your gut into your blood?
Does this mean eating Pacific saury could lower blood pressure?
Read the original research
Identification of novel angiotensin converting enzyme (ACE) inhibitory peptides from Pacific saury: In vivo antihypertensive effect and transport route.
International journal of biological macromolecules, 254(Pt 1), 127196
Citation
Wang, Shu; Zhang, Lu; Wang, Hui; Hu, Zizi; Xie, Xing; Chen, Haiqi; Tu, Zongcai. (2024). Identification of novel angiotensin converting enzyme (ACE) inhibitory peptides from Pacific saury: In vivo antihypertensive effect and transport route.. International journal of biological macromolecules, 254(Pt 1), 127196. https://doi.org/10.1016/j.ijbiomac.2023.127196