B7-33 is a synthetic single-chain peptide analogue of human relaxin-2 with a molecular weight of 2987.75 g/mol. Its structure corresponds to residues 7 through 33 of the B-chain of relaxin-2, a 27-amino acid linear fragment that retains the receptor-binding determinants for the relaxin family peptide receptor 1 (RXFP1) while eliminating the two-chain disulfide-linked architecture of the native heterodimeric relaxin-2 hormone. B7-33 was designed as a simplified, single-chain alternative that maintains RXFP1 binding and activation. Produced via solid-phase peptide synthesis, B7-33 is associated with RXFP1-mediated signalling and extracellular matrix remodelling pathways.

B7-33 is a structurally simplified relaxin-2 mimetic that overcomes the challenges associated with the native two-chain disulfide hormone. In vitro studies have characterised B7-33 as a functionally selective agonist of RXFP1: it binds the receptor with lower affinity than native H2 relaxin and is only a weak activator of the cAMP pathway, yet it drives ERK1/2 phosphorylation with potency comparable to H2 relaxin in cells that natively express RXFP1, and increases expression of the collagen-degrading enzyme matrix metalloproteinase-2 (MMP-2) in human cardiac fibroblasts and rat renal myofibroblasts [1]. In vivo rodent studies have shown that B7-33 prevented or reversed organ fibrosis and dysfunction with potency similar to H2 relaxin across three preclinical rodent models, and that an acute bolus of B7-33 reproduced the rapid vasoprotective/vascular-function effects of serelaxin in rat mesenteric artery, small renal artery and abdominal aorta [1,2], making B7-33 a reference compound in preclinical cardiovascular and fibrosis research examining single-chain, functionally selective RXFP1 agonism and pERK1/2–MMP-2-directed extracellular matrix remodelling in rodent models.

B7-33 is manufactured in a cGMP compliant, ISO9001 certified laboratory to a guaranteed purity of 98% or above. Every batch is independently tested using HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

Editorial Team

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed and approved 14 June 2026

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