TB-500 Peptide Capsules

Yakka Strength TB-500 Peptide Capsules is a Yakka Strength listing of TB-500, supplied as 60 capsules per pack and stocked through the Muscle Market range; the manufacturer does not state a strength per capsule on the label. It is sold for laboratory research only, is not for human consumption, and is sold to adults aged 18 and over. This page covers what the published research on TB-500 and thymosin beta-4 reports, what the label documents, the UK and anti-doping position, and how batch certificates are handled for Yakka Strength products.

About TB-500

TB-500 is the name used in the research-compound market for synthetic peptides based on thymosin beta-4, a 43-amino-acid protein present in most human cells. Products sold as TB-500 may contain the full sequence or a shorter fragment around the actin-binding region; the label on this listing does not say which. Thymosin beta-4 binds monomeric actin and has been studied in cell migration, angiogenesis and wound repair models. It is a peptide, so it is neither a steroid nor a SARM, even though the three are often sold side by side.

Identifier	Full thymosin beta-4	Fragment found in TB-500 products
Length	43 amino acids	7 amino acids (positions 17 to 23), acetylated at the N-terminus
Sequence	Full protein sequence	Ac-LKKTETQ
Molecular formula	C212H350N56O78S	C38H68N10O14
Molecular weight	about 4,963 g/mol	about 889 g/mol
PubChem CID	45382195	not listed here
InChIKey	UGPMCIBIHRSCBV-UHFFFAOYSA-N	not listed here

What the published research reports

A 2012 review by Goldstein and colleagues summarised the peptide's properties and the clinical programmes then under way in wounds, the cornea and cardiac repair. A 2010 randomised, placebo-controlled study gave intravenous pharmaceutical-grade thymosin beta-4 to healthy volunteers as single and repeated doses. Adverse events were infrequent and mild or moderate, and none was serious. It was a safety study, not an efficacy study, and it used injection rather than a capsule. None of those programmes has produced an approved medicine, and no published human work shows that a peptide of this size survives oral administration.

The chemistry of what is actually sold as TB-500 comes mostly from anti-doping laboratories. In 2012 the Ghent doping control laboratory analysed a TB-500 product by high-resolution mass spectrometry and identified the acetylated 17-23 fragment of thymosin beta-4, Ac-LKKTETQ, rather than the whole protein. The same year the Hong Kong Jockey Club's racing laboratory described TB-500 as a veterinary preparation built around that acetylated fragment and published a method that found it, and its breakdown products, in urine and plasma from horses given a single administration. Neither study measured any effect in people. Nothing above is a claim about this product.

This listing

• Manufacturer: Yakka Strength
• Compound: TB-500 (Thymosin Beta-4)
• Form: Capsules
• Pack size: 60 capsules
• Strength: the manufacturer does not state the amount per capsule on the label, so we do not list one
• Which peptide: the label does not say whether the capsules hold full thymosin beta-4 or the Ac-LKKTETQ fragment
• Batch certificate of analysis: shown where Yakka Strength supplies one for the batch we hold

With no stated strength, total milligrams per pack cannot be worked out, and the pack cannot be set against brands that print a figure. Our price per milligram guide explains why that matters.

TB-500 in the UK: buying, legal status and what to check

UK searches for this peptide cluster around three questions: whether it is legal ("TB 500 legal UK"), where it can be bought ("buy TB 500 UK", "TB 500 UK for sale", "TB 500 capsules UK"), and how to judge the seller.

The legal position

TB-500 is not a licensed medicine in the UK, has not been assessed by the MHRA, and is not an authorised food supplement. It is not a controlled drug either, which is why it can be supplied at all, but only as a laboratory research material to adults aged 18 and over and never for human consumption. Thymosin beta-4 and its derivatives, with TB-500 named as an example, are listed under section S2 (peptide hormones, growth factors and related substances) of the WADA Prohibited List and are prohibited at all times in sport. Our research guide covers the wider legal picture for research compounds, and the TB-500 and thymosin beta-4 research guide covers this peptide in depth.

What a trustworthy UK listing shows

• The peptide identified: whether the product is full thymosin beta-4 or the acetylated fragment, since the two differ roughly fivefold in molecular weight.
• A stated amount per capsule or vial, so a buyer can see what the pack is supposed to contain.
• Traceability: a lot code printed on every tub, matched by the lot code on its certificate.
• A named maker and a UK company behind the sale, reachable by email.
• Research-only terms: an 18+ restriction, no instructions for use and no promised results.
• Plain packaging, tracked delivery and a written returns policy.

How this listing measures up

Free Muscle is FreeMuscle LTD, a UK company in Scunthorpe. Orders ship by free tracked UK delivery in plain packaging, orders placed before 2pm Monday to Friday are processed the same working day, EU delivery takes three to seven working days, and unopened items can be returned within 30 days. Two points depend on the manufacturer and are not met on the label: the strength per capsule and the identity of the peptide. A batch certificate is the only document that could fill those gaps, and we show one only where Yakka Strength supplies it for the batch we hold. More in our UK supplier checklist.

Capsules compared with other forms

Most TB-500 on the market is freeze-dried powder in glass vials, often labelled "10mg", which is why "TB 500 10mg UK" is a common search. Capsules and tablets, as in this listing, are a newer format. The literature shows how each route was studied and where the obstacles lie.

The human programmes summarised in the 2012 review used intravenous infusion or preparations applied directly to skin or eye. The anti-doping work on the Ac-LKKTETQ fragment used horses given the veterinary preparation, not an oral form. No published study has measured whether either peptide reaches the blood intact after being swallowed. The general obstacle is digestion: stomach and intestinal proteases cleave peptide chains, and a 43-residue protein offers them many sites. Even the 7-residue fragment is a target, and the Hong Kong group's method looked for its metabolites as well as the parent peptide. Our article on whether oral peptides work covers the digestion problem across the class.

As materials the formats differ in handling rather than in molecule. A sealed vial of freeze-dried powder is dry and relatively stable, but once dissolved it becomes vulnerable to hydrolysis and contamination, and any measured volume depends on the mixing. A capsule holds a fixed fill of dry powder, usually with a filler, and its consistency from capsule to capsule depends on how evenly the batch was blended, which only a per-capsule content test can show. None of this implies that any format produces an effect.

TB-500 compared with BPC-157

BPC-157 is the peptide most often searched with this one ("TB 500 vs BPC 157", "TB 500 and BPC 157"). They are sold side by side and sometimes in the same bundle, but they come from unrelated proteins and sit in different parts of the WADA list.

Question	TB-500	BPC-157
Parent molecule	Thymosin beta-4, an intracellular actin-sequestering protein	A protein isolated from gastric juice
What is sold	Full 43-residue protein or the 7-residue Ac-LKKTETQ fragment; labels rarely say which	A single defined 15-residue sequence, GEPPPGKPADDAGLV
Size	About 4,963 g/mol (full) or about 889 g/mol (fragment)	About 1,419 g/mol
Human research	Full protein: a volunteer infusion study and early wound and eye programmes. Fragment: none	No published randomised controlled trial
UK status	Unlicensed; research material only	Unlicensed; research material only
WADA section	S2, named under thymosin beta-4 and its derivatives	S0, non-approved substances

The difference that matters most for a buyer is definition. BPC-157 has one sequence, so a certificate either finds it or does not. TB-500 is a trade name that has been applied to two different molecules, so a certificate must say which one it found before its purity figure means anything. The proposed biology also differs: thymosin beta-4's established role is holding actin in its unpolymerised form, which governs cell movement, while most BPC-157 work comes from rodent gut and tendon models. No human study has compared them, neither can be ranked above the other, and we publish no guidance on using them together. The BPC-157 collection lists every brand we hold, and BPC-157: what the research shows reviews its evidence.

Reading the certificate of analysis for this product

Yakka Strength is a third-party brand in the Muscle Market range, so the testing position differs from our own label. Every Free Muscle-brand batch is assayed by Janoshik Analytical, an independent laboratory, with the certificate sent on request by email. For Yakka Strength products we show a certificate of analysis only where the manufacturer supplies one for the specific batch we hold. A generic PDF with no batch number is not a batch certificate, and we do not present one as such. Email us with the product name and we will send what we hold, or say plainly that there is none. On a certificate for this pack, check these lines.

• Identity and method. LC-MS weighs the molecule and is the stronger test. The Ac-LKKTETQ fragment has a monoisotopic mass of about 888.5, usually seen as an ion near m/z 889.5 or, doubly charged, near m/z 445.3. Full thymosin beta-4 is far heavier and appears as a spread of multiply charged ions. HPLC alone only matches a retention time to a reference standard.
• Purity (%). The share of the chromatogram taken by the main peak. It grades cleanliness, not quantity.
• Content per capsule. The measured amount of peptide in a capsule, the figure the label omits. For peptides, check whether it is net peptide or total powder, since water and acetate counter-ions add weight.
• Batch number. It must match the lot printed on the tub you hold.
• Who tested it, and when. A named laboratory can be asked to confirm the report; the date shows whether it predates the stock.

For this brand, each missing field has a specific cost. No identity line means the certificate cannot settle whether the product is the fragment or the full protein. No content line means the strength remains unknown. A different or absent batch number means the report describes other material. Contact us with the lot number for what exists on current stock; our lab tests page and guide to reading a COA go further.

Detection, sport and testing

WADA names thymosin beta-4 and its derivatives, with TB-500 as the example, in section S2 of the Prohibited List. That section applies in and out of competition, across every sport that has adopted the World Anti-Doping Code, including testing by UK Anti-Doping. Under strict liability an athlete is responsible for any prohibited substance in their sample, whatever the label said.

Detection methods have been published for more than a decade. The Ghent laboratory proposed an LC-MS/MS strategy for the Ac-LKKTETQ fragment in plasma and urine in 2012, and the Hong Kong racing laboratory reported confirmation of the fragment at 0.01 ng/mL in equine urine and 0.02 ng/mL in equine plasma, together with its metabolites, after a single administration to horses. Those limits come from horse samples. No published study has set out how long TB-500 remains detectable in human urine, so the accurate statement is that it is detectable and the window is not established.

Storage, stability and handling

No stability study of TB-500 capsules has been published, so the expiry or best-before date printed by the manufacturer, if present, is the limit to work to. General peptide chemistry still identifies the risks. Moisture allows peptide bonds to hydrolyse and makes powder clump and capsule shells soften. Heat accelerates every degradation reaction, and light adds to it. Full thymosin beta-4 also contains a methionine residue, which oxidises readily, whereas the Ac-LKKTETQ fragment has none.

Keep the tub closed, in a cool, dry place away from direct light, radiators and damp rooms. If it is refrigerated, let it reach room temperature before opening so condensation does not form inside, and leave any desiccant sachet in the tub. Write the opening date next to the batch number. Handle the capsules as a laboratory reagent: gloves for opened capsules or loose powder, well away from food and drink, and out of reach of children and animals. Dispose of waste as chemical waste, not in household bins or drains. Keep capsules in their original container so they stay linked to the lot number and any certificate.

Glossary

• Thymosin beta-4: a 43-amino-acid protein found inside most human cells that binds actin; TB-500 products are based on it.
• Ac-LKKTETQ: the seven-residue fragment of thymosin beta-4 (positions 17 to 23), with an acetyl group added, that anti-doping laboratories identified in TB-500 products.
• Actin: the protein that forms filaments inside cells and drives cell shape and movement.
• G-actin: single, unpolymerised actin units; thymosin beta-4 holds a reserve of these.
• Acetylation: capping the first amino acid of a chain with an acetyl group (the "Ac" in Ac-LKKTETQ), adding 42 mass units.
• LC-MS/MS: liquid chromatography linked to tandem mass spectrometry, which separates, weighs and fragments each molecule for identification.
• m/z: mass-to-charge ratio, the value a mass spectrometer reports for each ion.
• Strict liability: under the World Anti-Doping Code, a positive sample is a violation whether or not the athlete knew what the product contained.

Related

• All brands of TB-500 we stock, compared, including Thoroughbred Labs TB-500 capsules
• All Yakka Strength products
• Research peptides and Yakka Strength BPC-157 capsules
• Batch testing and certificates of analysis
• Delivery and returns

This product is supplied for laboratory research use only. It has not been evaluated by the MHRA, EMA or FDA. It is not a medicine, not a food supplement and not for human consumption. Sold only to adults aged 18 and over. Nothing on this page is medical, dosing or usage advice, and descriptions of published studies are not claims about this product.

References

1. Goldstein AL, et al. Thymosin beta4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. PMID: 22074294.
2. Ruff D, et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-9. PMID: 20536472.
3. Esposito S, et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal. 2012;4(9):733-8. PMID: 22962027.
4. Ho EN, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin beta4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012;1265:57-69. PMID: 23084823.