The active tetrapeptide fragment of Thymosin Beta-4 with anti-fibrotic and cardioprotective properties.
TB-4 Fragment, specifically Ac-SDKP (N-acetyl-seryl-aspartyl-lysyl-proline), is a naturally occurring tetrapeptide released from the parent molecule Thymosin Beta-4 by the enzyme prolyl oligopeptidase. It is the smallest biologically active fragment of TB-4 and has been shown to possess potent anti-fibrotic, anti-inflammatory, and angiogenic properties independent of the full-length TB-4 molecule.
Ac-SDKP is produced endogenously and is normally degraded by angiotensin-converting enzyme (ACE). This is notable because ACE inhibitors — widely used cardiovascular medications — raise Ac-SDKP levels, and some of the cardioprotective and anti-fibrotic benefits of ACE inhibitors may actually be mediated through Ac-SDKP accumulation.
As a research peptide, TB-4 Fragment is being explored as a more targeted, smaller-molecule alternative to full-length TB-500 for tissue repair protocols, with particular interest in cardiac and renal fibrosis prevention.
Preclinical research demonstrates Ac-SDKP inhibits collagen deposition and fibroblast proliferation, reducing fibrosis in heart, kidney, and liver models. In cardiac ischemia-reperfusion models, Ac-SDKP reduced infarct size and improved cardiac function. The anti-fibrotic effects appear to be mediated through TGF-beta/Smad signaling inhibition.
The connection to ACE inhibitors is well-established: plasma Ac-SDKP levels increase 5-fold with ACE inhibitor treatment. Studies suggest that a significant portion of ACE inhibitor cardioprotection comes from Ac-SDKP accumulation rather than angiotensin II reduction alone.
📚 Key Reference: PMID: 15246113 (Ac-SDKP anti-fibrotic)
Limited human clinical data. Preclinical safety profile is favorable. As an endogenous peptide fragment, theoretical safety profile is reassuring. Long-term effects unknown. Consult your provider.
NOT FDA-approved. Research use only. Available through specialized compounding pharmacies.