At a glance
Effects
- Anti-fibrotic (preclinical): In rodent and in-vitro models, reduced scarring/fibrosis in heart, lung and kidney tissue with potency similar to H2 relaxin.[4][7][1]
- Cardioprotective (preclinical): In mouse models of myocardial infarction and cardiomyopathy, B7-33 attenuated adverse cardiac remodeling and reduced left-ventricular fibrosis.[3][8]
- MMP-2 upregulation: Increased activity of the collagen-degrading enzyme MMP-2 in cardiac fibroblasts and renal myofibroblasts, an effect blocked by an RXFP1-specific antagonist.[6][9]
- Receptor-selective signaling: Activates pERK1/2 without the cAMP-linked vascular/proliferative effects of relaxin, and unlike relaxin did not promote prostate tumor growth in vivo (mice).[4][2]
Synthetic relaxin-2 B-chain peptide; RXFP1 biased agonist[2][3]
Preclinical / research-only (no human trials)[5]
~6 min in vitro (serum)[10]
Parenteral in studies — subcutaneous; intranasal in lung models[8][4]
26 amino acids, single chain[2]
About B7-33
Every point here is drawn from public medical and harm-reduction sources. A bracketed number after a claim — like [1]— is a reference: tap it to open the exact source it's based on (numbered list at the bottom). It is not a rating or score. Educational information, not medical advice.
Product specifics
- Est. delivery
- 3–7 business days · EU tracked
Product details as stated by the vendor (claims, not independently verified). Delivery is our standard EU estimate.
What it is
B7-33 is a synthetic 26–amino-acid single-chain peptide derived from the B-chain of human relaxin-2 (H2 relaxin), engineered as a research tool to study anti-fibrotic signaling.[1][2] It is a research-grade laboratory compound, not an approved medicine or supplement, with evidence limited to cells and rodents and no human clinical trials.[5][6]
How it works
B7-33 acts as a "functionally selective" (biased) agonist at the relaxin family peptide receptor 1 (RXFP1), preferentially switching on the ERK1/2 (pERK) signaling pathway rather than the cAMP pathway activated by full relaxin.[2][3] Its anti-fibrotic action is reported to involve RXFP1–angiotensin II type 2 receptor heterodimers that drive pERK1/2 signaling and increase the collagen-degrading enzyme matrix metalloproteinase-2 (MMP-2), promoting breakdown of fibrotic collagen.[4] In rodent models this reversed or resolved fibrosis in heart, lung and kidney tissue with potency similar to relaxin.[4][7]
Risks & side effects
Most important: The single most important thing to know is that B7-33 is an experimental, research-only peptide: all evidence is preclinical (cells and rodents), there are no human clinical trials, and there is no established or approved human dose or safety profile.[5] Any human use is unstudied and unvalidated, and purity/sterility from research-chemical vendors is not guaranteed.[6]
Common
Serious
Rare
- Unknown — no clinical surveillance exists to characterise rare events for this peptide.[5]
Safety & harm reduction
- No human monitoring protocol is established. In animal cardiomyopathy studies, body weight and systolic blood pressure were tracked (B7-33 did not change SBP in that model).[8]
- Its MMP-2 / anti-fibrotic effect is mediated by RXFP1 and was blocked by an RXFP1-specific antagonist; human drug interactions are unstudied.[6]
- Supplied as a lyophilised powder requiring reconstitution and cold storage for laboratory use; there is no human dosing protocol.[5]
Dosage context
Sources
- 1.Wikipedia: B7-33
- 2.MedsBase: B7-33 Peptide overview
- 3.AHA Journal: B7-33 attenuates MI-related cardiac remodeling (mice)
- 4.PMC6013806: Single-chain functionally selective RXFP1 agonist
- 5.MedsBase (preclinical-only / no human trials note)
- 6.BiotechPeptides: B7-33 product / MMP-2 data
- 7.PMC10454739: Further developments toward minimal relaxin-2 derivative
- 8.PubMed 36753958: B7-33 maintains cardioprotection vs perindopril
- 9.PMC10094921: Lipidated single-B-chain relaxin derivative (half-life)
- 10.PMC10094921: B7-33 serum half-life ~6 min
This information is provided for educational and harm-reduction purposes only. It is not medical advice. These substances can carry serious health risks; effects and safe use vary by individual. Consult a qualified healthcare professional before use. Legal status varies by country — it is your responsibility to know your local law. We do not encourage misuse.