RESEARCH MONOGRAPH · KDC-MN-003

TB-500

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 3 min read

Our opinion on this compound

63/100

Sister compound to BPC-157 with thinner evidence and a weirder pharmacokinetic story

TB-500 gets bundled with BPC-157 in every recovery stack online, and that bundling does it a disservice. The compound itself is a synthetic fragment (the LKKTETQ active region, basically residues 17-23) of thymosin beta-4, the actual full-length 43-residue protein that's been studied for decades in wound healing and cardiac repair.

Here's the thing. Most of the real literature, the Goldstein lab work, the AdProtech trials, the cardiac infarct studies, is on full TB4, not the LKKTETQ fragment that gets sold as TB-500. The assumption that the short fragment recapitulates the parent protein's activity is plausible because the active-site motif is preserved, but it's been tested far less rigorously than people assume. The full peptide had legitimate phase 2 dermal ulcer data; the fragment has mostly preclinical extrapolation.

Mechanism is reasonably clear. G-actin sequestration, modulation of cell migration, upregulation of laminin-5 and integrins, anti-fibrotic effects through MRTF-A pathways. The actin biology is well established at the textbook level even if the in-vivo translation is murky.

Sourcing is where this gets interesting. Synthesizing a 7-residue fragment is trivial; synthesizing the full 43-residue TB4 is non-trivial and expensive. Most vendors selling TB-500 are selling the fragment, but a few mislabel full TB4 as TB-500 or vice versa. Always check the actual sequence on the COA, not just the product name. HPLC purity tends to be fine on the short version, the longer the peptide the more attention you want on the QC.

What we don't love is the half-life claim folklore (people quote multi-day half-lives that come from a single rat IM study and got extrapolated way beyond what the data supports). And the WADA ban gives this compound a regulatory taint that distorts the literature, since a lot of the human data is from horse racing rather than clean clinical work.

Verdict: real underlying biology, weaker evidence than its reputation suggests, and a sourcing layer you actually need to read carefully.

Evidence: 50
Mechanism: 65
Reliability: 60
Safety: 70
Sourcing: 75
Value: 60
Signal: 65
Staying power: 55

Plain-language summary Intrigue 72 / 100

TB-500 is a synthetic fragment of thymosin beta-4, a protein your body makes naturally that helps tissues heal. Researchers and athletes use it for tendon, muscle, and ligament repair. Like BPC-157, it has strong animal evidence but limited human clinical data. Stocked in the Kodiac catalog as a research-only powder for laboratory work; not a medicine, not for human consumption.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Synthetic peptide fragment of thymosin beta-4

A 43-residue acetylated synthetic peptide derived from the actin-sequestering protein thymosin beta-4, studied for tissue repair, cell migration, and angiogenic endpoints.

Abstract

TB-500 is the common research-grade designation for a synthetic acetylated peptide whose primary sequence is a fragment of human thymosin beta-4 (Tbeta4), a 43-residue actin-binding protein expressed at high concentration in platelets, leukocytes, and many other cells. The most frequently cited research-grade preparation is the full-length Tbeta4 sequence (43 amino acids; molecular weight approximately 4963 Da; CAS 77591-33-4) acetylated at the N-terminus to mimic the native post-translational modification. A small minority of vendor literature has used "TB-500" to refer to a shorter active fragment (LKKTETQ, residues 17 through 23 of Tbeta4), which is a different molecule with a different mass; investigators should confirm by mass spectrometry which sequence has been supplied. This monograph documents the full-length acetylated Tbeta4 sequence supplied as the Kodiac biolabs lot of record. Reported activities span actin sequestration, fibroblast and endothelial cell migration, angiogenic remodeling, attenuated inflammatory cytokine response, and accelerated repair of cardiac, dermal, corneal, and tendon injury models. Routes studied in the preclinical literature include intravenous, intramuscular, subcutaneous, intraperitoneal, oral, and topical administration. Plasma half-life following parenteral administration is short, on the order of one hour, but tissue retention extends substantially longer. Two Phase 2 trials of recombinant Tbeta4 in dry eye and pressure ulcer indications have been reported with mixed efficacy outcomes. The compound is not approved by any regulatory authority for human or veterinary use. The principal limitations on the strength of the published evidence are the variation in commercial preparations sold as "TB-500" and the scarcity of large independent randomized human trials.

Read the full monograph

The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, reported research dose ranges, sourcing and quality verification, reconstitution and handling, stack interaction considerations, and a curated reference list. Available as a research-use-only PDF download.

KDC-MN-003

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

Kodiac sells research compounds for investigative use only.

TB-500

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