A hexapeptide (LDKVFR) isolated from salmon skin collagen inhibited DPP-IV with IC50 of 128 µM through hydrogen bonds and hydrophobic interactions with the enzyme.
128 µM IC50salmon skin hexapeptide LDKVFR inhibits DPP-IV, the same enzyme targeted by diabetes drugs like sitagliptin
What the researchers found
Salmon skin collagen was broken down by four different enzymes. The trypsin-digested version showed the strongest DPP-IV inhibition at 66% at 10 mg/mL.
After separating the fragments by size, the smallest fraction (under a certain molecular weight) had an IC50 of 0.79 mg/mL. Further purification identified a novel peptide, LDKVFR, with an IC50 of 0.1 mg/mL (128.71 micromolar).
Molecular docking showed LDKVFR binds to DPP-IV through six hydrogen bonds and eight hydrophobic interactions, explaining its inhibitory activity.
Why it matters
DPP-IV inhibitors are an established class of diabetes medications. Finding natural peptides from food sources like salmon skin that can block this enzyme opens the door to food-derived alternatives or supplements.
Salmon skin is a fish processing byproduct, so using it to produce bioactive peptides could add value to waste material while creating potential health products.
The numbers in context
66.12% DPP-IV inhibition at 10 mg/mL (trypsin hydrolysate); LDKVFR IC50 = 0.1 mg/mL (128.71 μM); 6 hydrogen bonds, 8 hydrophobic interactions
How the study worked
This was a laboratory study. Researchers hydrolyzed salmon skin collagen with pepsin, trypsin, papain, or Alcalase. Fractions were separated by ultrafiltration and chromatography. DPP-IV inhibition was measured using an enzymatic assay. Binding was modeled using molecular docking software.
Who was studied
Salmon skin collagen hydrolysates (lab study)
What this study cannot tell us
This was entirely a lab-based study. No cell, animal, or human testing was done to see if LDKVFR survives digestion or reaches the bloodstream in active form.
The IC50 of 128 micromolar is relatively high compared to pharmaceutical DPP-IV inhibitors, which work at nanomolar concentrations.
How to read the evidence
Preliminary evidence from in vitro enzyme inhibition and molecular docking. No cell, animal, or human testing.
When this study was published
Published in 2020. Food-derived bioactive peptides for metabolic health continue to be explored.
The bigger picture
DPP-IV inhibitors (gliptins) are a major class of diabetes drugs. Finding natural peptide inhibitors from food waste like salmon skin could lead to functional foods or nutraceuticals for blood sugar management, while adding value to fish processing byproducts.
Questions still open
- Does LDKVFR survive human digestion to reach the bloodstream?
- How does its potency compare to drug DPP-IV inhibitors like sitagliptin?
- Could salmon skin hydrolysates be marketed as a functional food for blood sugar?
Common questions
What is DPP-IV and why inhibit it?
Could eating salmon help control blood sugar?
Read the original research
Identification of novel DPP-IV inhibitory peptides from Atlantic salmon (Salmo salar) skin.
Food research international (Ottawa, Ont.), 133, 109161
Citation
Jin, Ritian; Teng, Xiangyu; Shang, Jiaqi; Wang, Dangfeng; Liu, Ning. (2020). Identification of novel DPP-IV inhibitory peptides from Atlantic salmon (Salmo salar) skin.. Food research international (Ottawa, Ont.), 133, 109161. https://doi.org/10.1016/j.foodres.2020.109161