TB-500 — reference

TB-500: thymosin beta-4 fragment (research use only), approximate mass 889.0 Da (the commonly sold 7-residue fragment), Not well characterised in humans half-life. Identity, evidence base, analytical considerations and limitations.

Scope

A maintained identity and evidence reference for TB-500. It is deliberately narrow: what the molecule is, what has been published about it, and what an analytical report on it can and cannot establish. It contains no dosing recommendations and is not advice about anyone's care.

Where a figure is approximate this page says so. Where something is unknown, it says that instead of filling the gap.

Identity

Masses quoted here are approximate and are given for orientation when reading an analytical report. For a mass-error calculation, use the exact monoisotopic mass computed from the elemental composition rather than a rounded figure from a reference page, including this one.

What it is

The material sold as TB-500 is usually a short actin-binding fragment of thymosin beta-4 rather than the full 43-residue protein. The two are routinely conflated, including in supplier documentation, and the preclinical literature mostly concerns the full protein.

That conflation is the most important thing to understand about this compound. Evidence about thymosin beta-4 is not automatically evidence about a seven-residue fragment of it.

Evidence base

Published studies and programmes most relevant to this compound:

• No adequately powered, published, randomised controlled human trials known to us

As with BPC-157, identity is analytically easy and efficacy is unestablished in humans.

Individual digests for several of these are maintained separately in this commons and are linked from the evidence category. A digest is a summary with its criticisms attached; it is not a substitute for reading the paper.

Analytical considerations

The usual analytical approach depends on whether the molecule is a peptide; where it is not, peptide conventions do not transfer. A purity figure is an area percentage at a stated wavelength under a stated gradient, and it is not interchangeable with a content determination.

Three things a purity assay on this compound will not tell you: how much peptide is in the container (that requires a content assay), what the counter-ion is (that requires ion chromatography or NMR), and whether anything is present that does not elute under the method used.

See Reversed-phase HPLC for peptides and LC-MS identity confirmation for the method detail.

Status and legality

Research use only. Not approved for human use.

Material sold as research-use-only is not a licensed medicine, whatever it contains and however good its certificate is. That is a statement about regulatory status rather than about quality, and it is true of high-purity material as much as of poor material.

Limitations of this page

This is a reference page maintained by volunteers, reviewed on the date shown, and it will be out of date at some point after that date. It summarises published work rather than reproducing it, and a summary always loses something. Where the summary and the source disagree, the source is right.

If you find an error, the fastest route to fixing it is a topic in doc review naming the sentence and the source. The maintainers named above are notified.