TB-500 comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-03-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Lyophilised material is stable for extended periods when kept dry and cold, and suppliers typically recommend storage well below freezing. Once dissolved, the peptide is handled at refrigeration temperatures and used within a short period, because peptide bonds and the acetylated terminus can be affected by repeated freeze-thaw cycles, proteases, or extreme pH. Bacteriostatic water and saline are both described as solvents, although preservatives can interfere with some analytical workflows. Reconstituted solutions are inspected for particulates before use.
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.
TB-500 is a laboratory label applied to a short synthetic peptide that is widely described as a fragment of thymosin beta-4, an actin-binding protein present in most mammalian cells. Suppliers and review articles usually present TB-500 as the N-terminal region of that protein, but the exact sequence attached to the name is not consistent across sources. Some product descriptions list a seven-residue chain; others use the label loosely for the parent protein itself. Because of that variation, any technical discussion of TB-500 needs to state which sequence is meant.
Thymosin beta-4 contains 43 amino acids and has a reported molecular mass near 4963 Da. The short fragment most often associated with the TB-500 label, an acetylated chain beginning LKKTETQ, has a reported mass near 889 Da, so the two are easily separated in analytical work. Mass spectrometry and amino acid analysis can confirm which material is present in a given sample. Statements treating TB-500 and thymosin beta-4 as interchangeable are therefore imprecise, even though the two appear together in much of the same literature.
Interest in the compound comes largely from studies of the parent protein, which participates in actin sequestration, cell migration and tissue repair processes. Whether a short fragment reproduces those activities is a separate question that remains open in the published record. Many summaries describe mechanisms by analogy to thymosin beta-4 rather than from direct measurements on the fragment. Claims about activity should be treated as provisional unless a cited study specifies the exact peptide, its purity and the assay used.
| Property | Value | Notes |
|---|---|---|
| Analytical method | LC-MS/MS | Preferred confirmatory technique |
| Appearance | White to off-white powder | Lyophilised form |
| Solubility | Freely soluble in water | Also described in saline |
| Storage temperature | Below -20 °C for powder | Short-term refrigeration for solutions |
| Regulatory status | Prohibited in sport | Listed under peptide hormones |
Biological interest in this peptide centers on its relationship to actin dynamics. Thymosin beta-4 binds monomeric actin through an LKKTET motif, and a short sequence carrying that motif can compete with other actin-binding proteins in cell-free preparations. Investigators propose that such competition shifts the balance between filament assembly and disassembly, which in turn affects how readily a cell extends protrusions and migrates. Most of the supporting observations come from cultured cells and purified protein systems rather than from intact organisms.
Animal work has examined the peptide in models of cardiac injury, skin wounding, and corneal repair, with reported outcomes covering cell migration, inflammatory cell influx, and tissue remodeling. Several of those experiments used the full-length protein or longer fragments instead of the seven-residue sequence, which makes direct comparison between reports difficult. Results are generally described as tissue-dependent, and effect sizes vary considerably across laboratories. Independent replication is uneven, so the overall picture is incomplete rather than settled.
Proposed activity centers on actin sequestration and on the movement of cells during repair processes. In cell culture and animal models, the fragment has been associated with migration, tube formation, and tissue remodeling. These observations are frequently described as preliminary, because most published work uses rodent or in vitro systems rather than controlled human trials. Whether the short fragment reproduces the effects of the full protein remains an open question, and the relationship between dose, route, and measured outcome is not well characterized.
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.
== Biography == Youvan received an associate degree in electronics and a bachelor's degree in biology from Pittsburg State University. He received his Ph.D. degree in biophysics from UC Berkeley in 1981. Youvan was an associate professor of chemistry at MIT, where he specialized in the study of photosynthesis, specifically the spectral analysis of photosynthetic bacteria. Youvan, along with Mary M. Yang, developed instrumentation to study the spectra of bacteria directly from a petri dish.
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=== Chemicals === BASF produces a wide range of chemicals such as solvents, amines, resins, glues, electronic-grade chemicals, industrial gases, basic petrochemicals, and inorganic chemicals. The most important customers for this segment are the pharmaceutical, construction, textile, and automotive industries.
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Acne necrotica Acquired generalized hypertrichosis (acquired hypertrichosis lanuginosa, hypertrichosis lanuginosa acquisita) Acquired perforating dermatosis (acquired perforating collagenosis) Acrokeratosis paraneoplastica of Bazex (acrokeratosis neoplastica, Bazex syndrome) Acroosteolysis Acute paronychia Alopecia areata Alopecia neoplastica Anagen effluvium Androgenic alopecia (androgenetic alopecia) Anhidrosis (hypohidrosis) Anonychia Apparent leukonychia Beau's lines Blue nails Bromidrosis (apocrine bromhidrosis, fetid sweat, malodorous sweating, osmidrosis) Bubble hair deformity Central centrifugal cicatricial alopecia (follicular degeneration syndrome, pseudopelade of the central scalp) Chevron nail (herringbone nail) Chromhidrosis (colored sweat) Chronic paronychia Cicatricial alopecia Clubbing (drumstick fingers, Hippocratic fingers, watch-glass nails) Congenital onychodysplasia of the index fingers Disseminate and recurrent infundibulofolliculitis Erosive pustular dermatitis of the scalp (erosive pustular dermatosis of the scalp) Erythromelanosis follicularis faciei et colli Folliculitis decalvans Folliculitis nares perforans Fox–Fordyce disease Frontal fibrosing alopecia Generalized congenital hypertrichosis (congenital hypertrichosis lanuginosa) Generalized hyperhidrosis Graham-Little syndrome Granulosis rubra nasi Green nails Gustatory hyperhidrosis Hair casts (pseudonits) Hair follicle nevus (vellus hamartoma) Hairy palms and soles Half and half nails (Lindsay's nails) Hangnail Hapalonychia Hematidrosis Hirsutism Hook nail Hot comb alopecia Hypertrichosis cubiti (hairy elbow syndrome) Hypertrichosis simplex of the scalp Intermittent hair–follicle dystrophy Keratosis pilaris atrophicans Kinking hair (acquired progressive kinking) Koenen's tumor (Koenen's periungual fibroma, periungual fibroma) Koilonychia (spoon nails) Kyrle disease Leukonychia (white nails) Lichen planopilaris (acuminatus, follicular lichen planus, lichen planus follicularis, peripilaris) Lichen planus of the nails Lichen spinulosus (keratosis spinulosa) Lipedematous alopecia (lipedematous scalp) Localized acquired hypertrichosis Localized congenital hypertrichosis Longitudinal erythronychia Longitudinal melanonychia Loose anagen syndrome (loose anagen hair syndrome) Lupus erythematosus Madarosis Malalignment of the nail plate Male-pattern baldness Marie–Unna hereditary hypotrichosis (Marie–Unna hypotrichosis) Median nail dystrophy (dystrophia unguis mediana canaliformis, median canaliform dystrophy of Heller, solenonychia) Mees' lines Melanonychia Menkes kinky hair syndrome (kinky hair disease, Menkes disease) Monilethrix (beaded hair) Muehrcke's nails (Muehrcke's lines) Nail–patella syndrome (Fong syndrome, hereditary osteoonychodysplasia, HOOD syndrome) Neoplasms of the nailbed Nevoid hypertrichosis Noncicatricial alopecia Onychauxis Onychoatrophy Onychocryptosis (ingrown nail, unguis incarnatus) Onychogryphosis (ram's horn nails) Onycholysis Onychomadesis Onychomatricoma Onychophagia (nail biting) Onychophosis Onychoptosis defluvium (alopecia unguium) Onychorrhexis (brittle nails) Onychoschizia Onychotillomania Ophiasis Palmoplantar hyperhidrosis (emotional hyperhidrosis) Parakeratosis pustulosa Patterned acquired hypertrichosis Perforating folliculitis Pili annulati (ringed hair) Pili bifurcati Pili multigemini Pili pseudoannulati (pseudo pili annulati) Pili torti (twisted hairs) Pincer nails (omega nails, trumpet nails) Pityriasis amiantacea (tinea amiantacea) Platonychia Plica neuropathica (felted hair) Plummer's nail Premature greying of hair Prepubertal hypertrichosis Pressure alopecia (postoperative alopecia, pressure-induced alopecia) Pseudofolliculitis barbae (barber's itch, folliculitis barbae traumatica, razor bumps, scarring pseudofolliculitis of the beard, shave bumps) Pseudopelade of Brocq (alopecia cicatrisata) Psoriatic nails Pterygium inversum unguis (pterygium inversus unguis, ventral pterygium) Pterygium unguis (dorsal pterygium) Purpura of the nail bed Racquet nail (brachyonychia, nail en raquette, racquet thumb) Recurrent palmoplantar hidradenitis (idiopathic palmoplantar hidradenitis, idiopathic plantar hidradenitis, painful plantar erythema, palmoplantar eccrine hidradenitis, plantar panniculitis) Red lunulae Ross' syndrome Rubinstein–Taybi syndrome Setleis syndrome Shell nail syndrome Short anagen syndrome Splinter hemorrhage Spotted lunulae Staining of the nail plate Subungual hematoma Telogen effluvium Terry's nails Traction alopecia Traumatic alopecia Traumatic anserine folliculosis Triangular alopecia (temporal alopecia, temporal triangular alopecia) Trichomegaly Trichomycosis axillaris Trichorrhexis invaginata (bamboo hair) Trichorrhexis nodosa Trichostasis spinulosa Tufted folliculitis Tumor alopecia Twenty-nail dystrophy (sandpapered nails, trachyonychia) Uncombable hair syndrome (cheveux incoiffable, pili trianguli et canaliculi, spun-glass hair) Wooly hair nevus (woolly hair nevus) X-linked hypertrichosis
According to the DSM, it "is the more specific DSM-5 diagnostic category in which erectile dysfunction persists for at least 6 months and causes distress in the individual." The ICD-10, to which the DSM refers regarding Erectile dysfunction, lists it under Failure of genital response (F52.2). The latest edition of the ICD – namely, the ICD-11 – lists the condition as Male erectile dysfunction (HA01.1).
=== „Das Alphabet bis S“ (2023) === „Das Alphabet bis S“ [The Alphabet up to the letter S], Kermani's most expansive novel since „Dein Name“, can be read as a complementary text to it: while „Dein Name“ leads up to a separation between the male first-person narrator and his partner (without the breakup actually occurring in the novel), Das „Alphabet bis S“ looks back on a failed marriage. It is noteworthy that „Das Alphabet“ is told from the perspective of an unnamed female narrator, whose undated (but numbered) diary entries structure the text. The novel’s composition is more stringent than in „Dein Name“, partly because the 365 chapters—beginning with New Year's Day—cover exactly one year. And partly because—as the title suggests—the self-proclaimed “reader- writer” works her way alphabetically through the unread books on her bookshelf over the course of the year, reaching the surnames beginning with S. Kermani’s play with autofiction familiar from previous texts takes on a new direction here in that the protagonist's life, her reading, and thinking show numerous parallels to the author Navid Kermani (from her Muslim background to her work as a writer to her affinity for soccer to her committed commemoration of the dead). In addition, the combination of narrative and essayistic passages resembles the technique used in „Dein Name“. On the one hand, then, the separation between author and narrator seems obvious here. On the other hand, the text ironically suggests that it might be read as a femalely inverted mirror version of Kermani's own life and writing.
Sources: en.wikipedia.org
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.
Dry lyophilised powder is normally kept frozen and protected from moisture and light. Dissolved material is handled cold and used promptly to limit degradation.
It is not licensed as a medicine in major markets and is distributed as a research chemical. Sports organisations prohibit its use, and some countries restrict import and supply.
No. TB-500 is a trade-style label used for a synthetic peptide described as a fragment of thymosin beta-4, while thymosin beta-4 is the full 43-residue protein. The two differ in size and are not interchangeable terms in analytical work.