A nine-amino-acid peptide (VL-9) extracted from the red alga Acrochaetium sp. inhibits angiotensin-converting enzyme (ACE) in lab tests, suggesting potential as a natural blood-pressure-lowering food ingredient.
IC50 ≈ 433 µMThe concentration of VL-9 needed to inhibit 50% of ACE activity in laboratory tests
What the researchers found
The peptide VL-9 (sequence VGGSDLQAL), derived from the phycoerythrin protein of Acrochaetium sp. red algae, inhibited ACE with an IC50 value of 433.1 ± 1.08 µM.
Molecular docking confirmed that VL-9 acts as a non-competitive inhibitor, binding ACE outside its catalytic site. This is the first report of any bioactive peptide being identified from this particular red alga species.
Why it matters
Synthetic ACE inhibitors are a cornerstone of blood pressure treatment but carry side effects. Finding natural ACE-inhibiting peptides in edible algae could open the door to functional foods or nutraceuticals that help manage hypertension with fewer adverse effects, while also adding commercial value to underutilized marine resources.
How the study worked
Proteins from Acrochaetium sp. were digested with several proteolytic enzymes. The resulting hydrolysates were separated using reversed-phase and strong cation exchange chromatography. The most active fraction, generated by α-chymotrypsin digestion, was sequenced and identified as the nine-residue peptide VL-9. ACE inhibitory activity was measured in vitro, and molecular docking simulations were used to model how VL-9 interacts with the enzyme.
What this study cannot tell us
All experiments were conducted in vitro, so it is unknown whether VL-9 would survive digestion, reach the bloodstream, and lower blood pressure in living organisms. The IC50 of ~433 µM is relatively high compared to many food-derived ACE inhibitory peptides, which may limit practical potency. No animal or human trials were performed.
How to read the evidence
This is an in vitro biochemistry study with molecular docking. It provides early-stage evidence identifying a novel peptide and characterizing its enzyme-inhibition mechanism, but lacks any in vivo validation.
When this study was published
Published in 2022, this study is relatively recent and represents current work in marine-derived bioactive peptide discovery.
The bigger picture
Food-derived ACE inhibitory peptides are one of the most actively studied classes of bioactive peptides. Most research has focused on milk, fish, and soy proteins. This study expands the search to marine red algae, a largely untapped source, and adds to the growing catalog of natural peptides that could eventually be incorporated into functional foods for cardiovascular health.
Questions still open
- Can VL-9 resist breakdown by digestive enzymes well enough to remain active after oral consumption?
- How does VL-9's blood-pressure-lowering effect compare to established food-derived ACE inhibitory peptides in animal models?
- Could other bioactive peptides with stronger ACE inhibition be found in different fractions of Acrochaetium sp. protein?
Common questions
What is ACE and why does inhibiting it matter for blood pressure?
Could eating red algae lower blood pressure based on this study?
Read the original research
First Report of Screening of Novel Angiotensin-I Converting Enzyme Inhibitory Peptides Derived from the Red Alga Acrochaetium sp.
Marine biotechnology (New York, N.Y.), 24(5), 882-894
Citation
Windarto, Seto; Lee, Meng-Chou; Nursyam, Happy; Hsu, Jue-Liang. (2022). First Report of Screening of Novel Angiotensin-I Converting Enzyme Inhibitory Peptides Derived from the Red Alga Acrochaetium sp.. Marine biotechnology (New York, N.Y.), 24(5), 882-894. https://doi.org/10.1007/s10126-022-10152-w