Characterization of casein-derived peptide bioactivity: Differential effects on angiotensin-converting enzyme inhibition and cytokine and nitric oxide production
Bibliographic record
Abstract
Lactic acid bacteria (LAB) are used as starter cultures in the production of fermented dairy products and have the potential to confer bioactivity relevant to cardiovascular health, as they possess extensive proteolytic systems that liberate small bioactive peptides from larger milk proteins. Certain casein-derived peptides released by various LAB strains during fermentation have been shown to reduce hypertension and to modulate the immune system. We investigated the growth and peptide production of 2 LAB strains, Lactobacillus helveticus R0389 and Lactocaseibacillus rhamnosus R0011, their immunomodulatory activities, as well as their abilities to inhibit the angiotensin-converting enzyme (ACE). Peptide fractions collected from the cell-free supernatant of both medium-grown and milk fermentation cultures were assessed for ACE-inhibitory activity and their effects on the production of proinflammatory and regulatory cytokines by human THP-1 monocytes. Cultures were grown in medium, with or without supplementation with 0.1% casein, or in 3.25% milk fermented with each LAB strain. Casein supplementation increased the growth rate of both LAB strains, and significantly increased ACE-inhibitory activity of peptide fractions collected from both L. helveticus R0389 and L. rhamnosus R0011 cultures grown for 12 h. Fermentation peptide fractions of L. rhamnosus R0011 showed comparable ACE-inhibitory activity to known ACE inhibiting peptides Val-Pro-Pro and Ile-Pro-Pro (up to 79% inhibition) with a significant difference between culture peptide fractions and acidified and nonacidified control fractions collected after 6 d of fermentation. Many milk and casein-derived peptides reported in previous studies have been identified as part of a larger bioactive fraction. We synthesized a group of these peptides to individually assess both ACE-inhibitory and immunomodulatory activity. The known ACE inhibitors Val-Pro-Pro and Ile-Pro-Pro showed similar ACE inhibition to previously published results, while also inducing the production of the regulatory cytokine IL-10 by monocytes in the presence and absence of a proinflammatory stimulant. These synthesized peptides could also induce the production of nitric oxide (NO), a potent vasodilator, in human endothelial cell cultures. Investigating the relationships among these bioactive properties could improve the use of probiotic organisms and their secreted products in the food industry.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".