Peptides extracted from rainbow trout protein demonstrated antioxidant, ACE-inhibitory, and DPP-IV-inhibitory activities in lab assays, suggesting potential as multifunctional health-promoting food ingredients.
27.57% DPP-IV inhibition at 5 mg/mLThe fish protein hydrolysate reduced DPP-IV enzyme activity by about 28% at the highest tested concentration — modest compared to pharmaceutical inhibitors but notable for a food-derived ingredient with additional antioxidant and ACE-inhibitory activities.
What the researchers found
Peptides derived from enzymatic hydrolysis of rainbow trout protein demonstrated three types of biological activity in vitro: antioxidant effects (confirmed by DPPH, FRAP, ORAC, and ABTS assays), dose-dependent ACE inhibition (relevant to blood pressure), and DPP-IV inhibition of up to 27.57 ± 3.7% at 5 mg/mL (relevant to blood sugar regulation). These activities were confirmed at the cellular level using human intestinal Caco-2 cells, where the hydrolysate reduced hydrogen peroxide-induced reactive oxygen species and lipid peroxidation.
Why it matters
Finding food-derived peptides with multiple health-promoting activities opens the door to functional foods and nutraceuticals that could help manage blood pressure, blood sugar, and oxidative stress simultaneously. Fish processing generates large amounts of protein-rich byproducts, and converting these into bioactive peptides adds value while potentially creating accessible health ingredients.
How the study worked
Rainbow trout (Oncorhynchus mykiss) protein was subjected to enzymatic hydrolysis to generate low molecular weight peptide fractions. Antioxidant activity was tested using four in vitro assays (DPPH, FRAP, ORAC, ABTS). ACE and DPP-IV inhibitory activities were measured in cell-free assays showing dose-dependent inhibition. Cellular-level validation used human intestinal Caco-2 cells to assess ROS reduction, lipid peroxidation, and DPP-IV enzyme activity inhibition.
Who was studied
In vitro biochemical assays and human Caco-2 intestinal cell models — no human or animal subjects
What this study cannot tell us
All experiments were in vitro — there is no evidence that these peptides survive digestion intact or produce meaningful effects when consumed orally by humans. The DPP-IV inhibition of ~28% at 5 mg/mL is modest compared to pharmaceutical DPP-IV inhibitors. The specific peptide sequences responsible for the activities were not identified. No animal or human feeding studies were conducted.
How to read the evidence
This is an in vitro laboratory study using biochemical assays and cell culture models. While the multi-assay approach provides robust in vitro evidence, the complete absence of in vivo data means these findings are preliminary and cannot yet support health claims.
When this study was published
Published in 2023, this study contributes to the active and growing field of food-derived bioactive peptides. The specific trout-derived peptides identified here have not yet progressed to animal or human studies.
The bigger picture
The search for bioactive peptides from food sources is a rapidly growing field at the intersection of nutrition and pharmacology. Fish-derived peptides that inhibit both ACE and DPP-IV are particularly interesting because they could theoretically address hypertension and diabetes — two conditions that frequently co-occur. If these peptides can survive digestion and achieve effective concentrations in the body, they could become affordable functional food ingredients or nutraceutical supplements.
Questions still open
- Do these rainbow trout peptides survive gastrointestinal digestion and retain their biological activities when consumed orally?
- Which specific peptide sequences are responsible for each type of biological activity?
- How do the ACE and DPP-IV inhibitory potencies compare to pharmaceutical drugs currently used for hypertension and diabetes?
Common questions
What is DPP-IV inhibition and why does it matter for blood sugar?
Could eating fish actually provide these health benefits?
Read the original research
Rainbow Trout (Oncorhynchus mykiss) as Source of Multifunctional Peptides with Antioxidant, ACE and DPP-IV Inhibitory Activities.
Nutrients, 15(4)
Citation
Bartolomei, Martina; Cropotova, Janna; Bollati, Carlotta; Kvangarsnes, Kristine; d'Adduzio, Lorenza; Li, Jianqiang; Boschin, Giovanna; Lammi, Carmen. (2023). Rainbow Trout (Oncorhynchus mykiss) as Source of Multifunctional Peptides with Antioxidant, ACE and DPP-IV Inhibitory Activities.. Nutrients, 15(4). https://doi.org/10.3390/nu15040829