Starting from 99 peptides identified in Chlorella pyrenoidosa hydrolysate, researchers optimized a lead peptide to discover LR-5 (LRAKA), a novel nanomolar ACE inhibitor (IC50: 350 nM) that lowered blood pressure in vivo and binds ACE at an unconventional site.
IC50: 350 nMThe optimized peptide LR-5 inhibits ACE at nanomolar concentrations — approximately 76 times more potent than the original lead peptide and approaching pharmaceutical-grade activity from a food source
What the researchers found
99 peptides identified from Chlorella by LC-MS/MS. LVAKA (LV-5) IC50: 26.66 μM for ACE inhibition. Three peptides (LV-5, LKKAP, PGLRP) stable at extreme pH and temperature. Sequence optimization yielded LRAKA (LR-5): nanomolar ACE inhibition (IC50: 350 nM in vitro) and in vivo blood pressure reduction in rats. LR-5 binds an unconventional ACE site.
Why it matters
Most food-derived ACE-inhibitory peptides have micromolar potency, limiting practical utility. LR-5's nanomolar potency is exceptional — approaching pharmaceutical-grade activity. Combined with digestive stability and in vivo blood pressure reduction, this represents one of the most promising food-derived antihypertensive peptides discovered.
The numbers in context
99 peptides identified by LC-MS/MS. 10 selected by virtual screening. Lead peptide showed nanomolar ACE inhibition.
How the study worked
Trypsin hydrolysis of Chlorella pyrenoidosa. LC-MS/MS peptide identification (99 peptides). Virtual screening by molecular docking. In vitro ACE inhibition assays. Stability testing under pH/temperature extremes and simulated gastrointestinal digestion. Sequence optimization. In vivo blood pressure testing in rats. Molecular dynamics simulation for binding mechanism.
Who was studied
Chlorella pyrenoidosa protein hydrolysates
What this study cannot tell us
Animal study (rats) for in vivo validation — human blood pressure data needed. The optimization from LV-5 to LR-5 creates a semi-synthetic peptide, not purely 'natural.' Oral bioavailability in humans not confirmed. Single animal study may not reflect clinical efficacy.
How to read the evidence
Rated preliminary: impressive in vitro potency with in vivo blood pressure confirmation in rats. However, no human clinical data. The sequence optimization step means this is not purely a 'natural' food peptide.
When this study was published
Published in 2024. At the forefront of bioactive peptide optimization from microalgae sources.
The bigger picture
A nanomolar food-derived ACE inhibitor that survives digestion and works in vivo bridges the gap between functional foods and pharmaceuticals. Chlorella is already commercially produced at scale, making this a potentially viable source of natural antihypertensive ingredients.
Questions still open
- Could LR-5 be developed as a pharmaceutical antihypertensive peptide drug, or is it better suited as a nutraceutical?
- What is the significance of the unconventional ACE binding site — does it predict different clinical effects than standard ACE inhibitors?
- Is LR-5 absorbed intact from the human gut at bioactive concentrations?
Common questions
Can algae-derived peptides really lower blood pressure?
How does this compare to blood pressure medications?
Read the original research
Discovery of a novel nanomolar angiotensin-I converting enzyme inhibitory peptide with unusual binding mechanisms derived from Chlorella pyrenoidosa.
International journal of biological macromolecules, 280(Pt 2), 135873
Citation
Suo, Qishan; Wang, Jing; Wu, Ning; Geng, Lihua; Zhang, Quanbin; Yue, Yang. (2024). Discovery of a novel nanomolar angiotensin-I converting enzyme inhibitory peptide with unusual binding mechanisms derived from Chlorella pyrenoidosa.. International journal of biological macromolecules, 280(Pt 2), 135873. https://doi.org/10.1016/j.ijbiomac.2024.135873