Summary
B7-33 is a simplified, single-chain version of the hormone relaxin-2, designed to keep relaxin’s anti-fibrotic effects while being easier to make. In mouse models of lung and heart fibrosis it reduced collagen deposition.
Structure
A single-chain peptide based on the B chain of human relaxin-2, without the A chain.
How it works
B7-33 activates the relaxin receptor RXFP1 with a bias toward the pERK pathway linked to anti-fibrotic signalling, rather than the cAMP pathway.
Research use cases
Areas where B7-33 has been studied. Inclusion here does not mean it works for that purpose.
- Pulmonary and cardiac fibrosis models
- Kidney fibrosis models
What the research found
Design and anti-fibrotic activity
Hossain and colleagues reported that B7-33 matched native relaxin’s anti-fibrotic effects in models of lung and heart fibrosis.1
Safety and open questions
No human data.
Regulatory status
Preclinical. Sold for research use.
Status was accurate when this page was last reviewed on October 26, 2026. Regulations change; check with the relevant authority before relying on it.
B7-33: common questions
Is relaxin approved as a drug?
Serelaxin, recombinant relaxin-2, was tested in acute heart failure but did not reduce mortality in the RELAX-AHF-2 trial and was not approved. B7-33 is an earlier-stage research compound.
Is B7-33 approved for human use?
Preclinical. Sold for research use.
References
- Hossain MA, Kocan M, Yao ST, et al. (2016). A single-chain derivative of the relaxin hormone is a functionally selective agonist of the G protein-coupled receptor, RXFP1. Chemical Science.
Links open a PubMed search for the exact title, or the original source where one is given.