research chemical is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-07-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
Regulatory status differs by country, but TB-500 is not an approved pharmaceutical in major jurisdictions. It is commonly sold as a research chemical for laboratory use, which places responsibility for identity and purity on the supplier and the laboratory. Published human data are limited, and most reports involve preclinical models or cell culture. Questions about whether the fragment mimics all actions of thymosin beta-4, and under which conditions, remain open. Independent verification of any material is therefore a practical requirement in research settings.
TB-500 is a synthetic heptapeptide with the sequence Ac-LKKTETQ. It corresponds to a short N-terminal region of thymosin beta-4, a 43-amino-acid protein found in many cell types. The fragment contains an actin-binding motif, which is one reason it appears in laboratory studies of cell migration and cytoskeletal dynamics. TB-500 is not the full-length protein and is produced as a research chemical rather than an approved therapeutic agent. Its molecular weight is approximately 889 Da.
| 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 |
Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.
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.
Identity and purity checks for peptide material typically combine reversed-phase high-performance liquid chromatography with mass measurement, since retention time alone cannot confirm a sequence. Mass measurement verifies the expected molecular mass within instrument tolerance, while chromatographic peak area provides a purity estimate. Anti-doping analysis of urine uses related but more sensitive workflows, sometimes after solid-phase extraction. For research material, batch documentation, certificate content, and independent testing are common points of scrutiny, because supply chains outside pharmaceutical regulation vary widely in the paperwork they provide.
Reconstitution of a lyophilized peptide is normally done with sterile water or a suitable buffer under aseptic conditions. Adding solvent down the vial wall and allowing gentle dissolution instead of vigorous vortexing reduces the chance of aggregation, which can lower the effective concentration of the resulting solution. Concentrated stocks are usually diluted into working buffer shortly before use. Because no standard preparation protocol exists for TB-500 specifically, laboratories adapt general peptide handling practice, and reported results may reflect differing preparation choices.
The compound circulates in the literature as a research reagent rather than an approved therapeutic. Regulatory agencies in several countries have not authorized it for medical use, and sporting bodies list related thymosin beta-4 peptides among prohibited substances. Suppliers typically market it with a purity figure and a certificate of analysis, while peer-reviewed clinical reports remain sparse. Discussions therefore often separate laboratory findings from anecdotal reports, and reviewers tend to note the small size and methodological limits of the available studies.
TB-500 refers to a synthetic peptide fragment derived from the actin-binding region of thymosin beta-4, a protein present in most mammalian cells. The full protein contains forty-three amino acids, while the commonly sold fragment is a much shorter acetylated sequence, often cited as LKKTETQ. The fragment retains part of the actin-binding motif but lacks the remainder of the parent protein. Material sold under this name is usually lyophilized powder intended for laboratory research, and it is not a finished pharmaceutical product.
1936: Danish seismologist and geophysicist Inge Lehmann discovered that the Earth has a solid inner core distinct from its molten outer core. 1937: Canadian forensic pathologist Frances Gertrude McGill assisted the Royal Canadian Mounted Police in establishing their first forensic detection laboratory. 1937: Suzanne Comhaire-Sylvain became the first female Haitian anthropologist and the first Haitian person to complete a PhD, receiving her doctoral degree from the University of Paris. 1937: Marietta Blau and her student Hertha Wambacher, both Austrian physicists, received the Lieben Prize of the Austrian Academy of Sciences for their work on cosmic ray observations using the technique of nuclear emulsions. 1938: Nigerian physician Elizabeth Abimbola Awoliyi became the first woman to be licensed to practise medicine in Nigeria after graduating from Trinity College Dublin and the first West African female medical officer with a license of the Royal Surgeon (Dublin). 1938: Canadian geologist Alice Wilson became the first woman appointed as Fellow to the Royal Society of Canada. 1938: South African naturalist Marjorie Courtenay-Latimer discovered a living coelacanth fish caught near the Chalumna river. The species had been believed to be extinct for over 60 million years. It was named latimeria chalumnae in her honour.
As a chemist he is known best for his work on organic synthesis, including discovery of the aldol reaction Hans-Joachim Born (1909–1987), German radiochemist who participated in the Soviet nuclear weapons programme Carl Bosch (1872–1940), German chemist, pioneer in the field of high-pressure industrial chemistry. Nobel Prize in Chemistry 1931 Octave Leopold Boudouard (1872–1923), French chemist who discovered the Boudouard reaction: combination of carbon and carbon dioxide to form carbon monoxide at high temperatures Jean-Baptiste Boussingault (1802–1887), French chemist with work in agricultural science, petroleum science and metallurgy
=== Ectopic fat === Ectopic fat is the storage of triglycerides in tissues other than adipose tissue, that are supposed to contain only small amounts of fat, such as the liver, skeletal muscle, heart, and pancreas. This can interfere with cellular functions and hence organ function and is associated with insulin resistance in type 2 diabetes. It is stored in relatively high amounts around the organs of the abdominal cavity, but is not to be confused with visceral fat. The specific cause for the accumulation of ectopic fat is unknown. The cause is likely a combination of genetic, environmental, and behavioral factors that are involved in excess energy intake and decreased physical activity. Substantial weight loss can reduce ectopic fat stores in all organs and this is associated with an improvement of the function of those organs. In the latter case, non-invasive weight loss interventions like diet or exercise can decrease ectopic fat (particularly in heart and liver) in overweight or obese children and adults.
=== Acute kidney impairment === Acute kidney impairment is one of the more complicated complications of Rhabdomyolysis. The risk of kidney injuries is increased from factors such as hypovolemia, abnormalities from electrolytes, and the severity of muscle injury. Kidney dysfunction typically develops 1–2 days after the initial muscle damage. If supportive treatment is inadequate to manage this, renal replacement therapy (RRT) may be required. RRT removes excess potassium, acid, and phosphate that accumulate when the kidneys are unable to function normally and is required until kidney function is regained. Three main modalities of RRT are available: hemodialysis, continuous hemofiltration and peritoneal dialysis. The former two require access to the bloodstream (a dialysis catheter), and peritoneal dialysis is achieved by instilling fluid into the abdominal cavity and later draining it. Hemodialysis, which is normally done several times a week in chronic kidney disease, is often required daily in rhabdomyolysis. Its advantage over continuous hemofiltration is that one machine can be used multiple times a day, and that continuous administration of anticoagulant drugs is not necessary. Hemofiltration is more effective at removing large molecules from the bloodstream, such as myoglobin, but this does not seem to confer any particular benefit. Peritoneal dialysis may be difficult to administer in someone with severe abdominal injury, and it may be less effective than the other modalities.
He then may or may not have been induced to sign it", since it ran counter to Faisal's other public and private statements at the time. A 1 March interview by Le Matin quoted Faisal as saying: This feeling of respect for other religions dictates my opinion about Palestine, our neighbor. That the unhappy Jews come to reside there and behave as good citizens of this country, our humanity rejoices given that they are placed under a Muslim or Christian government mandated by The League of Nations. If they want to constitute a state and claim sovereign rights in this region, I foresee very serious dangers. It is to be feared that there will be a conflict between them and the other races. Referring to his 1922 White Paper, Churchill later wrote that "there is nothing in it to prohibit the ultimate establishment of a Jewish State." And in private, many British officials agreed with the Zionists' interpretation that a state would be established when a Jewish majority was achieved. When Chaim Weizmann met with Churchill, Lloyd George and Balfour at Balfour's home in London on 21 July 1921, Lloyd George and Balfour assured Weizmann "that by the Declaration they had always meant an eventual Jewish State," according to Weizmann minutes of that meeting. Lloyd George stated in 1937 that it was intended that Palestine would become a Jewish Commonwealth if and when Jews "had become a definite majority of the inhabitants", and Leo Amery echoed the same position in 1946.
Sources: en.wikipedia.org
CO2 + OH− ⇌ HCO−3 A reaction similar to this is almost instantaneous with carbonic anhydrase. The structure of the active site in carbonic anhydrases is well known from a number of crystal structures. It consists of a zinc ion coordinated by three imidazole nitrogen atoms from three histidine units. The fourth coordination site is occupied by a water molecule. The coordination sphere of the zinc ion is approximately tetrahedral. The positively-charged zinc ion polarizes the coordinated water molecule, and nucleophilic attack by the negatively-charged hydroxide portion on carbon dioxide proceeds rapidly. The catalytic cycle produces the bicarbonate ion and the hydrogen ion as the equilibrium:
==== Root parsley ==== Another type of parsley is grown as a root vegetable, the Hamburg root parsley (P. crispum Radicosum Group, syn. P. crispum var. tuberosum). This type of parsley produces much thicker roots than types cultivated for their leaves. Although seldom used in Britain and the United States, root parsley is common in central and eastern European cuisine, where it is used in soups and stews, or simply eaten raw, as a snack (similar to carrots). Although root parsley looks similar to the parsnip, which is among its closest relatives in the family Apiaceae, its taste is quite different.
Acquired generalized lipodystrophy (Lawrence syndrome, Lawrence–Seip syndrome) Adiposis dolorosa (Dercum's disease) Alpha-1 antitrypsin deficiency panniculitis (alpha1-protease deficiency panniculitis, alpha1-proteinase deficiency panniculitis) Atrophic connective tissue panniculitis Barraquer–Simons syndrome (acquired partial lipodystrophy, cephalothoracic lipodystrophy, progressive lipodystrophy) Benign symmetric lipomatosis (benign symmetric lipomatosis of Launois–Bensaude, Madelung's disease) Centrifugal abdominal lipodystrophy (centrifugal lipodystrophy, lipodystrophia centrifugalis abdominalis infantalis) Chronic erythema nodosum (erythema nodosum migrans, subacute migratory panniculitis of Vilanova and Piñol, subacute nodular migratory panniculitis) Cold panniculitis (popsicle panniculitis) Congenital generalized lipodystrophy (Berardinelli–Seip syndrome) Cytophagic histiocytic panniculitis Drug-induced lipodystrophy Factitial panniculitis Familial partial lipodystrophy (Köbberling–Dunnigan syndrome) Gouty panniculitis Hemihyperplasia–multiple lipomatosis syndrome HIV-associated lipodystrophy Involutional lipoatrophy Lipoatrophia annularis (Ferreira–Marques lipoatrophia) Lipoatrophia semicircularis (semicircular lipoatrophy) Lipodermatosclerosis (chronic panniculitis with lipomembranous changes, hypodermitis sclerodermiformis, sclerosing panniculitis, stasis panniculitis) Lipohypertrophy Localized lipodystrophy Neutrophilic lobular panniculitis Nodular vasculitis Non-progressive late-onset linear hemifacial lipoatrophy Pancreatic panniculitis (enzymatic panniculitis, pancreatic fat necrosis, subcutaneous fat necrosis) Poland's syndrome Post-steroid panniculitis Sclerema neonatorum Sclerosing lipogranuloma (paraffinoma) Septal panniculitis Subcutaneous fat necrosis of the newborn Traumatic panniculitis Tumor lysis syndrome Weber–Christian disease (relapsing febrile nonsuppurative panniculitis)
=== Alternative medicine === The Food and Drug Administration (FDA) does not recommend alternative therapies to treat sexual dysfunction. Many products are advertised as "herbal viagra" or "natural" sexual enhancement products, but no clinical trials or scientific studies support the effectiveness of these products for the treatment of ED, and synthetic chemical compounds similar to sildenafil have been found as adulterants in many of these products. The FDA has warned consumers that any sexual enhancement product that claims to work as well as prescription products is likely to contain such a contaminant. A 2021 review indicated that ginseng had "only trivial effects on erectile function or satisfaction with intercourse compared to placebo".
Sources: en.wikipedia.org
According to a classified (secret) report by the US Army National Ground Intelligence Center in Military Intelligence Digest dated 24 January 1997, agent designated A-232 and its ethyl analogue A-234 developed under the Foliant programme "are as toxic as VX, as resistant to treatment as soman, and more difficult to detect and easier to manufacture than VX". The binary versions of the agents reportedly use acetonitrile and an organic phosphate "that can be disguised as a pesticide precursor."
== Adverse effects == Although the absorption of betamethasone dipropionate is small, when used for prolonged periods of time (periods exceeding two weeks), or across a large surface area (total use greater than 50 grams per week), it can have adverse effects. One such effect is the ability of the corticosteroid to suppress the hypothalamic–pituitary–adrenal axis. This can lead to a depression in the release of adrenal hormones such as cortisol and adrenocorticotropic hormone, or ACTH. Symptoms of HPA axis suppression are often subtle and variable, but can often be detected using simple blood or urine tests such at ACTH stimulation test or urinary free cortisol. Those at increased risk for HPA axis suppression are those who are more likely to absorb more of the steroid through the skin. These groups include:
The laurel leaves in the coat of arms of Kaskinen, Finland (Swedish: Kaskö), may have been meant to refer to local flowering, but its origin may also be in the name of the family Bladh (Swedish: blad; 'leaf'); two members of the family – a father and a son – acquired both town rights and the status of staple town for the village at the time.
Fallout: After a Nuclear Attack – slideshow by Life magazine The Effects of Nuclear War Archived 2016-08-28 at the Wayback Machine (1979) — handbook produced by the United States Office of Technology Assessment (hosted by the Federation of American Scientists) Nuclear Attack Planning Base – 1990 (1987) — assessment of the effects of a major Soviet attack on the United States produced by the Federal Emergency Management Agency (hosted by the Federation of American Scientists) Nuclear War Survival Skills (1979/1987) — handbook produced by Oak Ridge National Laboratory (use menu at left to navigate) Ground Zero: A Javascript simulation of the effects of a nuclear explosion in a city British RAF manual on the effects of nuclear explosions dated 1955 20 Mishaps That Might Have Started Accidental Nuclear War by Alan F. Philips, M.D. Nuclear Files.org Archived 2013-03-29 at the Wayback Machine Interactive Timeline of the Nuclear Age Annotated bibliography on nuclear warfare from the Alsos Digital Library for Nuclear Issues DeVolpi, Alexander, Vladimir E. Minkov, Vadim A. Simonenko, and George S. Stanford. 2004. Nuclear Shadowboxing: Contemporary Threats from Cold War Weaponry, Vols. 1 and 2. Fidlar Doubleday. Air Weapons for the Cold War Archived 2013-07-24 at the Wayback Machine An in depth history of American air weapons and nuclear bombs from the reference book American Combat Planes of the 20th Century by Ray Wagner Nuclear Emergency and Radiation Resources NUKEMAP3D – a 3D nuclear weapons effects simulator powered by Google Maps.
Street purity of 2C-B, when tested, has been found to be relatively high. Researchers in Spain found that 2C-B samples in the country doubled between 2006 and 2009, switched from primarily powder form to tablets, and exhibited "low falsification rates". An analysis of street samples in the Netherlands found impurities "in small percentages"; only one of the impurities, the N-acetyl derivative of 2C-B, could be identified, and comprised 1.3% of the sample. The authors suggested that this compound was a by-product of 2C-B synthesis. In 2011, street prices in the United States ranged between $10 and $30 per tablet when purchased in small quantities. Larger retail purchases cost between $200 and $500 per gram. Wholesale purchases of 2C-B would lower the price ($100 to $300 per gram in 2001, $30 to $100 on the darknet in 2020).
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.
TB-500 is a synthetic heptapeptide corresponding to a fragment of thymosin beta-4. It is used in laboratory research and is not an approved drug.