If you have been reading about thymosin beta-4 and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-12-30. Numbers and descriptions here follow the published literature rather than marketing material.
Identity and purity are assessed with a small set of standard techniques. Reverse-phase high-performance liquid chromatography gives a purity estimate from peak area, usually recorded at 214 or 220 nanometers, where the peptide bond absorbs. Mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidized species. Amino acid analysis or tandem mass spectrometry sequencing can verify the sequence itself. Additional quality attributes include water content, residual trifluoroacetic acid carried over from purification, and endotoxin where the material is intended for biological work.
The compound is most often distributed as a lyophilized powder, appearing white to off-white and forming a loose cake or fluffy solid. It is hygroscopic to some degree, so brief exposure to humid air can add water weight and complicate weighing. The peptide dissolves readily in water and in neutral aqueous buffers, and aqueous solubility is generally described as high, well above the concentrations used in typical assays. Some polar organic solvents are also usable, which matters when a concentrated stock is prepared before dilution into buffer.
Sports authorities classify the peptide as a prohibited substance, and it appears on the World Anti-Doping Agency list under peptide hormones, growth factors, and related substances. Racing jurisdictions for horses and dogs have issued separate restrictions, and several national bodies treat it as a controlled or prescription-only item. As a research chemical it is sold without a therapeutic indication, and labels usually state that the product is not for human or veterinary use. Regulatory treatment therefore varies by country.
Detection in biological matrices generally relies on liquid chromatography coupled with tandem mass spectrometry, because the peptide lacks a convenient ultraviolet chromophore beyond the amide backbone. Immunoassays have been described, but antibodies raised against the fragment can cross-react with the full-length protein or with unrelated peptides, so findings usually require confirmation by a second technique. Sample preparation typically involves protein precipitation followed by solid-phase extraction. Reported detection windows depend on dose, route, matrix, and instrument sensitivity.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized cake or fluffy solid |
| Water solubility | High | Dissolves in water and neutral buffers |
| Dry storage | -20 °C or below | Dry, dark, desiccated |
| Reconstituted storage | Frozen, single thaw | Repeated freeze-thaw promotes loss |
| Purity method | Reverse-phase HPLC | Peak area read at 214 or 220 nm |
Laboratory work on thymosin beta-4 describes binding to monomeric actin and effects on cell migration, angiogenesis, and inflammatory signaling in cultured cells. Animal models have examined skin, corneal, and cardiac repair after injury, with outcomes reported mainly in preclinical literature. Most of that evidence concerns the parent protein rather than preparations labelled TB-500, so extrapolation from animal findings to a specific commercial product remains uncertain. Whether the two behave identically in living systems has not been established in controlled human studies.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
TB-500 is a synthetic peptide preparation marketed under a name derived from thymosin beta-4, a 43-residue actin-binding protein first isolated from thymus tissue. The full-length protein has a reported molecular mass near 4963 Da, while material sold as TB-500 is often described as a fragment containing the actin-binding motif LKKTETQ. Because suppliers use the name inconsistently, published sources sometimes refer to the same label as a fragment, a synthetic copy, or a related analog. This naming ambiguity complicates direct comparison of reports across studies.
Interest in the fragment grew during the 1990s and 2000s, when it moved from laboratory work into sports and supplement markets. Anti-doping bodies added thymosin beta-4 fragments to prohibited lists, and a small number of adverse analytical findings have been reported in competition testing. Published controlled human trials remain scarce. Most mechanistic evidence comes from cell culture and animal models, and those studies examine endpoints such as cell migration, wound closure and inflammation markers. That evidence supports research interest but does not establish clinical benefit, and broad regenerative claims should be read as unverified.
TB-500 is a short synthetic peptide sold under a trade name rather than a systematic chemical name. Suppliers usually describe it as a fragment of thymosin beta-4 and ship it as a lyophilised powder intended for laboratory use. Because the label is commercial, the exact sequence attributed to it is not fully consistent across catalogues, and some listings present a seven-residue peptide while others describe related fragments of similar length. It is not an approved medicine in any major jurisdiction, and it is handled as a research chemical.
Thymosin beta-4 is a 43-residue actin-binding protein found in most mammalian cell types, where it participates in cytoskeletal regulation and cell migration. TB-500 represents only a short fragment of that protein and does not include the remaining residues. Whether the isolated fragment reproduces the full range of activities reported for the intact protein remains an open question. Researchers commonly treat the two as related but distinct entities when comparing results.
Published work involving this sequence spans actin-binding assays, cell-migration studies, wound-healing models, and cardiovascular or musculoskeletal experiments. Much of the biological rationale derives from in vitro systems and animal models, and the number of controlled human studies is small. Reported outcomes vary across preparations, doses, and routes, which complicates comparison between studies. Reviews generally describe the evidence base as preliminary rather than settled. Mechanistic explanations are often proposed by analogy to the parent protein rather than demonstrated directly.
The designation TB-500 circulates in laboratory and catalog contexts without a single agreed definition. Most product listings apply it to an N-terminally acetylated seven-residue fragment of thymosin beta-4, while other listings attach the same label to the full 43-residue protein. Because the term is commercial rather than systematic, two entries bearing identical names may describe different molecules. Any documentation should therefore state which sequence a given sample is claimed to contain.
The fragment most often associated with the name carries the sequence Ac-LKKTETQ, matching residues 17 through 23 of thymosin beta-4. That region holds the actin-binding motif responsible for much of the parent protein's biochemical activity. Apart from N-terminal acetylation the peptide is unmodified and contains no disulfide bonds, so it shows little ordered secondary structure in solution. Full-length thymosin beta-4 is instead a 43-residue polypeptide of roughly 4.9 kDa found widely across mammalian cell types.
==== Traumatic brain injury ==== Atomoxetine is sometimes used in the treatment of cognitive impairment and frontal lobe symptoms due to conditions like traumatic brain injury (TBI). It is used to treat ADHD-like symptoms such as sustained attentional problems, disinhibition, lack of arousal, fatigue, and depression, including symptoms from cognitive disengagement syndrome. A 2015 Cochrane review identified only one study of atomoxetine for TBI and found no positive effects. Aside from TBI, atomoxetine was found to be effective in the treatment of akinetic mutism following subarachnoid hemorrhage in a case report.
== Further reading == Juego, Bonn (2017). "The Philippines 2017: Duterte-led authoritarian populism and its liberal-democratic roots" (PDF). Asia Maior; the Journal of the Italian Think Tank on Asia Founded by Giorgio Borsa in 1989. XXVIII. Viella s.r.l. & Associazione Asia Maior: 129–163. ISSN 2385-2526. Archived from the original (PDF) on December 1, 2022. Retrieved December 1, 2022. "The Punisher". Eye for an Eye. (Vice) Bethesda Softworks LLC. Archived from the original on March 10, 2016. Retrieved September 14, 2016.
== History == Glenmark was incorporated on 18 November 1977. It began producing generic drugs and active pharmaceutical ingredients for markets in India, Russia, and Africa, and went public on Indian stock exchanges in 1999. Glenn Saldanha, Gracias's son, became managing director in 2001 after working at Eli Lilly and Company and PricewaterhouseCoopers. Under his leadership the company expanded internationally; by 2008 it had become one of India's larger pharmaceutical manufacturers by sales volume, and in 2011 consolidated worldwide sales reached $778 million. That year Glenmark established its first North American manufacturing facility in Monroe, North Carolina. In the mid-2010s, Glenmark changed direction. The generic drug industry was seeing fewer patent expirations, and the company began developing proprietary medicines in oncology, dermatology, and respiratory treatments. It researched drugs internally and licensed them to larger pharmaceutical companies. By 2016, four Glenmark drugs were in clinical development. A respiratory treatment was licensed for commercialisation in North America and Japan, and a diabetes drug was licensed to Merck's German division. Sales that fiscal year were approximately ₹81 billion (about $1.25 billion), ranking it fourth among India's pharmaceutical manufacturers by revenue. Glenmark built a consumer healthcare business in India that included the antifungal Candid, launched in 1979, the respiratory medication Ascoril, and La Shield. It divested the intimate hygiene brand VWash to Hindustan Unilever in March 2020.
Arterial pH < 7.3 (taken by sampling of blood from an artery); or, All three of an international normalized ratio (INR) of greater than 6.5, serum creatinine of greater than 300 micromoles per litre and the presence of encephalopathy (of grade III or IV). These three are markers of coagulopathy, kidney function and mental status.
The parenteral route is any route that is not enteral (par- + enteral). Parenteral administration can be performed by injection, that is, using a needle (usually a hypodermic needle) and a syringe, or by the insertion of an indwelling catheter. Locations of application of parenteral administration include:
Sources: en.wikipedia.org
== Desorption mass spectrometry matrix == In mass spectrometry this compound is often abbreviated as "3-NBA" or "m-NBA." It has been used as a liquid matrix for fast atom bombardment and matrix-assisted laser desorption ionization. In electrospray ionization 3-NBA is doped into low surface tension spray solvents to increase analyte charging.
== Research == Chlorpromazine has tentative benefit in animals infected with Naegleria fowleri and shows antifungal and antibacterial activity in vitro. Like other phenothiazine derivatives such as perphenazine, trifluoperazine, and triflupromazine, it inhibits tubulin polymerization.
== Medical uses == Suvorexant is used for the treatment of insomnia, characterized by difficulties with sleep onset and/or sleep maintenance, in adults. At a dose of 15 to 20 mg and in terms of treatment–placebo difference, it reduces time to sleep onset by up to 10 minutes, reduces time awake after sleep onset by about 15 to 30 minutes, and increases total sleep time by about 10 to 20 minutes. A 2017 systematic review and meta-analysis of randomized controlled trials of suvorexant for insomnia likewise found that the medication improved subjective sleep onset, subjective total sleep time, and subjective sleep quality when assessed at one to three months of treatment. The effectiveness of approved doses of suvorexant (≤20 mg) in the treatment of insomnia is said to be modest. Network meta-analyses have assessed the sleep-promoting effects of suvorexant and have compared them to those of other orexin receptor antagonists like lemborexant and daridorexant as well as to other sleep aids including benzodiazepines, Z-drugs, antihistamines, sedative antidepressants (e.g., trazodone, doxepin, amitriptyline, mirtazapine), and melatonin receptor agonists. A major systematic review and network meta-analysis of insomnia medications published in 2022 found that suvorexant had an effect size (standardized mean difference (SMD)) against placebo for treatment of insomnia at 4 weeks of 0.31 (95% CITooltip confidence interval 0.01 to 0.62).
== Dried plasma spot == This technology is similar to dried blood spot sampling however instead of collecting whole blood on a membrane, it separates red blood cells from plasma. A dried plasma spot (DPS) is usually a drop of capillary blood on a plasma separation card, the first membrane will filter all the red blood cells, while the second membrane aborbs the cell free plasma. This method is ideal for processing and storage of plasma.
Sources: en.wikipedia.org
Short transit at ambient temperature is generally tolerated, but long-term storage at room temperature is not recommended. Heat, moisture, and light all accelerate degradation. Cold, dry, dark storage is the conventional choice.
Suppliers typically quote a percentage derived from reverse-phase HPLC peak area. That figure reflects the relative amount of the main peak and does not by itself confirm identity or exclude related impurities. Mass spectrometry is commonly paired with it for confirmation.
Peptides purified by reverse-phase chromatography often carry trifluoroacetate as a counter-ion, which adds mass and can affect solubility and apparent behavior in assays. Acetate and hydrochloride forms are also offered. Knowing which form is present matters when calculating how much peptide a given weight contains.
The most common approach is liquid chromatography with tandem mass spectrometry after extraction from blood or urine. Immunoassays exist but are generally treated as screening tools because of cross-reactivity.