Evidence Grade E — Very limited evidence. 0 published studies. 0 registered clinical trials.
Medically reviewed by a licensed medical professional
B7-33 is a simplified, single-chain version of the hormone relaxin, being investigated in preclinical research for heart and kidney fibrosis (scarring). Full-length relaxin requires complex two-chain assembly that makes manufacturing difficult — B7-33 solves this by delivering the key activity from one chain. No human clinical trials have been conducted. It has no regulatory approval.
Stresam Peptide (B7-33) is also known by these brand and alternate names:
No published studies found on PubMed.
B7-33 has no marketing authorisation. No human clinical trials have been registered. The evidence base consists entirely of preclinical studies in cell culture and animal models of cardiac and renal fibrosis.
B7-33's single-chain design solves a major manufacturing challenge — full-length relaxin requires complex two-chain assembly. If the biased agonism translates clinically, the simplified structure could make relaxin-based therapy practically viable. However, clinical translation has not yet been attempted.
Research suggests B7-33 activates the relaxin receptor (RXFP1) with a 'biased' signalling profile — selectively activating anti-fibrotic pathways while avoiding pathways that promote uncontrolled cell growth. This selectivity may offer safety advantages over full-length relaxin. These observations are from cell culture and animal studies.
Research suggests consistent anti-fibrotic results across multiple animal models, with a critical safety advantage: unlike full-length relaxin, B7-33 does not appear to promote tumour growth. Publication in high-quality journals and contributions from multiple research groups strengthen the evidence. However, the 6-minute half-life in blood is a major barrier to clinical translation. No human data of any kind exist, sample sizes in animal studies are small (6-8), and no formulation suitable for human use has been developed. Products from unregulated channels lack pharmaceutical quality assurance.
PeptideTrace tracks 0 registered clinical trials for Stresam Peptide (B7-33) sourced from ClinicalTrials.gov.
No trials registered on ClinicalTrials.gov for this compound.
B7-33 is a single-chain linear peptide containing 27 amino acids derived from human relaxin-2 B-chain residues 7-33 (sequence: VIKLSGRELVRAQIAISGMSTWSKRSL). Its molecular weight is approximately 2,984 Da (CAS 1818415-56-3, PubChem CID 318164840). Design features include truncation of 6 N-terminal residues from B1-29, addition of 4 C-terminal residues (KRSL), and replacement of cysteines at positions 11 and 23 with serines (C11S, C23S) to prevent dimerization. In vitro serum half-life is approximately 6 minutes. Developed by Hossain, Bathgate, Wade, and Samuel at the Florey Institute/University of Melbourne/Monash University (first published 2016).
Research suggests B7-33 is a biased agonist at the relaxin family peptide receptor 1 (RXFP1), a Gq/11-coupled GPCR. It binds with significantly lower affinity than H2 relaxin (pKi 5.54 vs. 8.96) in overexpressing cells but achieves equivalent potency in cells endogenously expressing RXFP1. The critical feature is functionally selective (biased) signaling: B7-33 preferentially activates pERK1/2 over cAMP, which avoids cAMP-linked tumor-promoting effects. Research suggests B7-33 activates RXFP1-AT2R heterodimers, inducing selective downstream signaling through pERK1/2 to MMP-2 (collagen-degrading metalloproteinase). The NO-cGMP pathway also contributes to anti-fibrotic effects.
All data are preclinical with no registered clinical trials. In vitro: B7-33 at 30 nM significantly promoted MMP-2 in human cardiac fibroblasts comparable to H2 relaxin (p<0.01 vs. untreated). In isoprenaline-induced cardiomyopathy (Alam et al. 2023, mice, N=6-8/group), B7-33 at 0.25 mg/kg/day SC retained all cardioprotective effects of full relaxin and showed more rapid anti-fibrotic effects than perindopril. In myocardial infarction model (Devarakonda et al. 2020, JAHA), B7-33 reduced infarct size at 24h and preserved cardiac function at 7 days. In preeclampsia RUPP models (N=8/group), B7-33 normalized blood pressure, reduced proteinuria, and lowered TNF-alpha. B7-33 did not promote prostate tumor growth, unlike full H2 relaxin.
The information on this page is provided for educational and research reference purposes only. This is not medical advice. Always consult a qualified healthcare professional before making any health-related decisions.
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Evidence Reviews
This content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making decisions about your health.
