Peps
What is B7-33?
B7-33 is a short, lab-designed peptide built from part of relaxin-2, a natural hormone best known for its role in pregnancy. It was designed to keep relaxin's anti-scarring and blood-vessel effects in a smaller molecule. Its evidence comes from animal and cell studies, not people.
Biological role or research focus
Heart and anti-scarring (fibrosis) research in animals.
This was one mouse model of heart attack in male animals, with short follow-up. The full hormone relaxin (serelaxin) looked promising in animals but did not improve survival in a large human heart-failure trial, which is a reminder that animal heart results often do not carry over.
Role reference: B7-33, a Functionally Selective Relaxin Receptor 1 Agonist, Attenuates Myocardial Infarction-Related Adverse Cardiac Remodeling in Mice · 2020 ↗
Names you may encounter
B7 33 · B7-33 relaxin analog · single-chain relaxin mimetic
Search terms can include brands, combinations, or historical names. They are not automatic product equivalents.
- Class / identity
- Synthetic single-chain peptide based on the B-chain of the hormone relaxin-2; acts on the relaxin receptor RXFP1
- Research focus
- Heart and anti-scarring (fibrosis) research in animals
- Featured evidence
- Animal and cell study
- Source check
- October 4, 2026
Biology & proposed mechanism
B7-33 activates the relaxin receptor (RXFP1) and favors one signaling route (ERK1/2) linked to tissue protection. In the featured study it helped heart-muscle cells survive simulated injury and lowered a marker of cell stress. Protecting cells in a dish and in mice does not establish a benefit in human hearts.
Research context & identity
This profile covers preclinical research on heart injury and fibrosis (excess scar tissue), including studies of coatings that release B7-33 to reduce scarring around implants. B7-33 has no approved medical use, and no human trials were found when this page was checked.
What does the evidence show?
Evidence map
Every study featured on this page, grouped by what was actually tested. Human studies count most; animal and cell results often do not carry over to people.
| Study | Type | Population / model |
|---|---|---|
| B7-33 after experimental heart attack in mice (2020) | Animal and cell study | Adult male mice with a surgically induced heart attack, plus heart-muscle cells studied in the lab. |
Selected published evidence, with the population, findings, and limits kept together. These original summaries draw on publication abstracts; they are not a systematic review.
Animal and cell study · 2020
B7-33 after experimental heart attack in mice
What did this publication test, and what did it find?
- Population / model
- Adult male mice with a surgically induced heart attack, plus heart-muscle cells studied in the lab.
- Study design
- Mice had a coronary artery blocked for 30 minutes and then reopened, and were treated with B7-33 or an inactive solution. Infarct size was measured at 24 hours and heart function by ultrasound up to 7 days.
- Main finding
- The damaged area was about half as large with B7-33 (22% vs 45% of the area at risk), and the heart's pumping measure was better preserved at 24 hours and 7 days.
- Limits & context
- This was one mouse model of heart attack in male animals, with short follow-up. The full hormone relaxin (serelaxin) looked promising in animals but did not improve survival in a large human heart-failure trial, which is a reminder that animal heart results often do not carry over.
Read the original paper for methods, adverse events, funding, and conflicts of interest. Publisher access may require a subscription.
Registered human trials
No study naming B7-33 as an intervention was found on ClinicalTrials.gov when we last checked (October 8, 2026). That means no registered human trial, not proof that none has ever been done elsewhere.
Search additional PubMed records ↗New editorial updates
New source discoveries
Links appear automatically. Unreviewed discoveries are not verified medical findings.
Safety & precautions
Safety & what remains unknown
No human safety data exist. Relaxin signaling affects blood vessels, connective tissue and the reproductive system, so effects outside the heart are unknown. Research-chemical products are unregulated.
Evidence boundaries
This was one mouse model of heart attack in male animals, with short follow-up. The full hormone relaxin (serelaxin) looked promising in animals but did not improve survival in a large human heart-failure trial, which is a reminder that animal heart results often do not carry over.
Regulatory status
- U.S. FDA approval
- Not approved
No FDA-approved drug containing this substance found in Drugs@FDA (openFDA data updated 2026-10-07). source - FDA compounding (503A bulk list)
- Not on the lists
Not found on FDA's 503A category 1, 2 or 3 lists (updated May 14, 2026) or the category 2 safety-risk page (updated April 22, 2026). source - World Anti-Doping Agency (2026)
- Likely prohibited under a class rule · S0 Non-approved substances
Not named. S0 prohibits (at all times) any pharmacological substance not covered by another section and with no current approval by any government health authority for human therapeutic use; no such approval was found, so it is likely covered. source
Checked October 8, 2026. Rules change; follow the source links for the current status. Regulatory tracker.
This is not a complete list of contraindications, interactions, or adverse effects. Medicine labels apply to specific products and indications; research-use listings are not interchangeable with approved medicines.
What are people discussing?
No editorial transcript note has been reviewed for this profile yet. Below are the matching video records available for exploration; title and caption matches are not verified claims.
Watch the source discussions
0 matching video records · 0 with captions indexed.
Across the full library, 30 caption files are indexed from 20,199 inventoried videos. Most transcripts remain unreviewed. Select a thumbnail or timestamp to watch inside PepsRadar. Thumbnail images load from YouTube.
No matching video has been identified in the current snapshot.
Sources & supplier listings
Listings are grouped by the vendor’s stated identity. Blends and modified derivatives are labeled separately. Inclusion is not a quality assessment or an endorsement.
We have not added a supplier for this profile. Missing products and coded listings are not filled with guesses.
Catalog checked 2026-10-04. Seller listings retain their stated intended use. Shops covered: BioLongevity Labs, BioLongevity Supplements, American Peptides, PSPeptides, Peptide.Express, Offline Peptides, Alera Research, Pinnacle Peptide Labs. This is not a market-wide comparison. Affiliate participation does not determine evidence or editorial coverage.
Questions worth asking
- Is B7-33 the same as relaxin?
- What material, population, and route were actually studied?
- This was one mouse model of heart attack in male animals, with short follow-up. The full hormone relaxin (serelaxin) looked promising in animals but did not improve survival in a large human heart-failure trial, which is a reminder that animal heart results often do not carry over.
- What adverse effects, uncertainty, and conflicts of interest does the original source report?
Frequently asked questions
Is B7-33 the same as relaxin?
No. It is a small piece of relaxin-2 redesigned as a single chain. It acts on the same receptor in lab studies, but it is a different molecule, and results for relaxin or serelaxin do not automatically apply to it.
Does the publication verify a supplier’s product?
No. The tested material and a commercial listing need separate identity and batch checks. A research-use disclaimer does not establish clinical suitability.
References & editorial record
Source notes checked 2026-10-04. Original PepsRadar summaries. Not reviewed by a medical professional. Topic grouping is editorial navigation, not a treatment recommendation. Video notes specify which excerpts were reviewed; no full transcripts are published.