Everything below concerns thymosin beta-4. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-11-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
TB-500 is a research peptide whose sequence matches residues 17 to 23 of thymosin beta-4, a 43-residue protein present in most mammalian cells. The chain is seven amino acids long, written as LKKTETQ, and is normally supplied with an acetyl group on the N-terminus. Suppliers list it as a lyophilised powder under the code name TB-500, and the same sequence appears elsewhere in catalogues as the thymosin beta-4 actin-binding fragment. The label is commercial rather than systematic, so no single authority fixes exactly what TB-500 denotes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
The seven-residue chain carries several polar and charged side chains, so it dissolves readily in water and in aqueous buffers near neutral pH. No cysteine is present, so disulphide formation is not a concern and reducing agents are unnecessary. Dilute ammonium hydroxide or acetonitrile-water mixtures are sometimes used for stock solutions when initial dissolution is slow. Strongly alkaline conditions and prolonged contact with oxidising agents are avoided because they can modify lysine-containing stretches, and haze in solution usually signals incomplete dissolution or aggregated material.
Identity and purity are checked with reversed-phase high-performance liquid chromatography, which separates the target sequence from truncated or deletion analogues, and with mass spectrometry, which confirms the expected molecular mass. Amino acid analysis and peptide mapping give orthogonal confirmation but are used less often outside specialist laboratories. Counter-ion content varies: material purified on trifluoroacetic acid gradients retains trifluoroacetate, and ion exchange can convert the salt form. Residual water and solvent are measured by Karl Fischer titration or thermogravimetric analysis, and any purity figure should be read together with the method used to obtain it.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Supplied as a lyophilised cake in sealed vials |
| Solubility class | Freely soluble in water | Polar and charged side chains dominate the sequence |
| Typical storage temperature | -20 °C or below | Dry and dark; a desiccant is often recommended |
| Identity confirmation | Mass spectrometry | Observed mass compared with the theoretical value |
| Common synonyms | Thymosin beta-4 fragment | Also written as T beta 4 fragment 17-23 |
Thymosin beta-4 is a naturally occurring protein of 43 amino acids found in most mammalian cells, where it binds actin monomers and influences filament dynamics. It was first isolated from thymus tissue in the early 1980s, and its actin-binding activity was later mapped to a short region near the N-terminus. The synthetic fragment sold as TB-500 was designed to reproduce that region rather than the full protein. Whether a short fragment reproduces the behavior of the intact molecule remains an open question, since the parent protein carries additional structural elements outside the binding region.
Published research on the intact protein is substantial, covering actin regulation, cell migration, and wound models. Research using the heptapeptide fragment specifically is far smaller, and much of the circulating material originates in supplier documentation rather than peer-reviewed reports. Where fragment studies do exist, they often employ different sequences, chain lengths, or terminal modifications, which complicates direct comparison across papers. Readers encountering claims about TB-500 should therefore separate evidence about thymosin beta-4 from evidence about the fragment itself.
Discussion of the compound frequently appears alongside other short peptides described as fragments of larger proteins. That grouping is convenient but can be misleading, because fragment length, charge, and modification state determine how a peptide behaves in solution and in any experimental system. A seven-residue acetylated peptide and a full-length protein differ in mass by roughly an order of magnitude, and they cannot be assumed to share distribution or binding properties. Precision about which molecule is under discussion is the single most useful step when reading such material.
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.
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== Advantages == The nasal cavity is covered by a thin mucosa which is well vascularised. Therefore, a drug molecule can be transferred quickly across the single epithelial cell layer directly to the systemic blood circulation without first-pass hepatic and intestinal metabolism. The effect is often reached within 5 minutes for smaller drug molecules. Nasal administration can therefore be used as an alternative to oral administration, by crushing or grinding tablets or capsules and snorting or sniffing the resulting powder, providing a rapid onset of effects if a fast effect is desired or if the drug is extensively degraded in the gut or liver. Large-molecule drugs can also be delivered directly to the brain by the intranasal route, the only practical means of doing so, following the olfactory and trigeminal nerves (see section below), for widespread central distribution throughout the central nervous system with little exposure to the blood. This delivery method to the brain was functionally demonstrated in humans in 2006, using insulin, a large peptide hormone that acts as a nerve growth factor in the brain.
In Virus (2019), directed by Aashiq Abu, Kallingal played nurse Akhila, a character based on Lini Puthussery — the nurse who died treating Kerala's first patient in the 2018 Nipah virus outbreak. Lini Puthussery's husband, who attended a screening of the film, said that Kallingal's portrayal was faithful and delivered "a flawless performance as Lini". Kallingal co-produced the film with Aashiq Abu under their production banner OPM Cinemas. Sowmya Rajendran described her performance as "expressive". In the 2021 film Santhoshathinte Onnam Rahasyam, directed by Don Palathara, Kallingal played an entertainment journalist opposite Jitin Puthenchery. Baradwaj Rangan described her performance as "terrific". The film won her Best Actress at the Diorama International Film Festival. In 2023 she appeared in Neelavelicham, a horror drama co-produced with Aashiq Abu. In 2025, Kallingal starred in Theatre, written and directed by Sajin Baabu, playing Meera, a woman who has lived an isolated life on a coastal Kerala island alongside her elderly mother. The film explores the conflict between traditional belief and modern science. The film had its world premiere at the Eurasian Bridge International Film Festival in Yalta on 9 October 2025, before its theatrical release on 16 October 2025. The role was physically demanding; director Sajin Baabu noted that Kallingal spent several hours atop a coconut tree for a single scene and completed multiple retakes despite sustaining bruises.
Safrole is listed as a Table I precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances. Due to their role in the manufacture of MDMA, safrole, isosafrole, and piperonal are Category I precursors under regulation no. 273/2004 of the European Community. In the United States, safrole is currently a List I chemical. The root bark of American sassafras contains a low percentage of steam-volatile oil, which is typically 75% safrole. Attempts to refine safrole from sassafras bark in mass quantities are generally not economically viable due to low yield and high effort. However, smaller quantities can be extracted quite easily via steam distillation (about 10% of dry sassafras root bark by mass, or about 2% of fresh bark). Demand for safrole is causing rapid and illicit harvesting of the Cinnamomum parthenoxylon tree in Southeast Asia, in particular the Cardamom Mountains in Cambodia. However, it is not clear what proportion of illicitly harvested safrole is going toward MDMA production, as over 90% of the global safrole supply (about 2,000 tonnes or 2,200 short tons per year) is used to manufacture pesticides, fragrances, and other chemicals. Sustainable harvesting of safrole is possible from leaves and stems of certain plants, including the roots of camphor seedlings.
Sources: en.wikipedia.org
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Denaturing gels are run under conditions that disrupt the natural structure of the analyte, causing it to unfold into a linear chain. Thus, the mobility of each macromolecule depends only on its linear length and its mass-to-charge ratio. Thus, the secondary, tertiary, and quaternary levels of biomolecular structure are disrupted, leaving only the primary structure to be analyzed. Nucleic acids are often denatured by including urea in the buffer, while proteins are denatured using sodium dodecyl sulfate, usually as part of the SDS-PAGE process. For full denaturation of proteins, it is also necessary to reduce the covalent disulfide bonds that stabilize their tertiary and quaternary structure, a method called reducing PAGE. Reducing conditions are usually maintained by the addition of beta-mercaptoethanol or dithiothreitol. For a general analysis of protein samples, reducing PAGE is the most common form of protein electrophoresis. Denaturing conditions are necessary for proper estimation of molecular weight of RNA. RNA is able to form more intramolecular interactions than DNA which may result in change of its electrophoretic mobility. Urea, DMSO and glyoxal are the most often used denaturing agents to disrupt RNA structure. Originally, highly toxic methylmercury hydroxide was often used in denaturing RNA electrophoresis, but it may be method of choice for some samples. Denaturing gel electrophoresis is used in the DNA and RNA banding pattern-based methods temperature gradient gel electrophoresis (TGGE) and denaturing gradient gel electrophoresis (DGGE).
In order to establish the required properties for applications, a rigorous characterization of the phase separation phenomenon can be carried out by different spectroscopic and calorimetric methods, including nuclear magnetic resonance (NMR), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), infrared spectroscopy (IR), Raman spectroscopy, and Differential scanning calorimetry (DSC).
==== Pharmacological significance ==== ACE is a pharmaceutical target of ACE inhibitor drugs, which decrease the rate of conversion of angiotensin I to angiotensin II, and of angiotensin II receptor antagonists which block angiotensin II AT1 receptors. Angiotensin II results in increased inotropy, chronotropy, catecholamine and sensitivity, aldosterone levels, vasopressin levels, and cardiac remodeling and vasoconstriction through AT1 receptors on peripheral vessels (conversely, AT2 receptors impair cardiac remodeling). This is why ACE inhibitors and ARBs help to prevent remodeling that occurs secondary to angiotensin II and are beneficial in congestive heart failure.
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Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 matches only residues 17 to 23 of that chain. The two are related but differ in size, and a method that identifies one does not automatically identify the other.
It corresponds to the actin-binding region of thymosin beta-4. Commercial synthesis reproduces that seven-residue stretch, usually with an acetyl group on the N-terminus.
It is not authorised as a medicine in the United States or the European Union and is distributed as a research chemical. Labels consequently carry research-use-only statements rather than clinical indications.
Divide it into single-use aliquots and hold them frozen at -20 °C or below, protected from light. Repeated thawing of one container is the main avoidable source of variability.