Everything below concerns immune modulation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-07-24. Numbers and descriptions here follow the published literature rather than marketing material.
Within the immune system, the peptide acts on several cell types rather than a single target. Reported activities include promotion of T-cell maturation, enhancement of natural killer cell activity, and modulation of cytokine production by dendritic cells and macrophages. Some of these effects appear to operate through toll-like receptor signaling, though the precise receptor-level mechanism remains debated. Whether the observed immune changes translate into clinical benefit is a separate question and depends on the indication studied.
The peptide was described in the 1970s as a component of thymic extracts, and early research focused on restoring immune function in immunodeficiency states. A synthetic version entered clinical development in the 1980s and is approved as a drug in several countries for conditions such as chronic hepatitis B and certain immunodeficiencies. Approval status varies widely by jurisdiction, and in the United States it is not an approved therapeutic. Regulatory and clinical positions differ, so statements about efficacy should be tied to specific indications and studies.
Thymosin alpha-1 is a short peptide of 28 amino acid residues first described in the 1970s as a component of thymic extracts. Its N-terminal residue carries an acetyl group, and the sequence is highly conserved across mammalian species. The peptide is not encoded as a standalone gene product; it is released by proteolytic cleavage from the N-terminus of prothymosin alpha, a larger acidic nuclear protein. That precursor relationship places it within a broader family of thymic and immune-associated peptides that have been studied for decades.
The activity of this peptide is generally described as immunomodulatory rather than directly antimicrobial. Experimental work links it to signaling through certain Toll-like receptors on dendritic cells and to downstream maturation of antigen-presenting cells. Reported effects include expansion of T cell subsets, shifts in cytokine profiles, and increased natural killer cell activity. These observations come largely from cell culture and animal models, and the precise receptor-level events in humans remain incompletely characterized.
The compound has been investigated as an adjunct in chronic viral hepatitis and as a vaccine adjuvant, with results that vary by study design and population. Regulators in some countries have approved a synthetic form for specific indications, while other agencies have not. Whether the peptide produces consistent clinical benefit across diverse patient groups is still an open question, and many trials have been small. Its status is therefore best described as investigational in many contexts and established only narrowly.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic peptide, 28 residues | N-terminal fragment of prothymosin alpha |
| Molecular mass | About 3108 Da | Acetylated form |
| Isoelectric point | Near 4.2 | Acidic peptide |
| Appearance | White to off-white lyophilized powder | Common supplied form |
| Typical storage | -20 °C or below, dry | Solution stability is lower |
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
20世纪70年代，研究者从胸腺提取物中纯化出多种小肽，Tα1是其中被较早表征的一种。最初的制备依赖组织匀浆和层析步骤，产量低且成分复杂。随着固相肽合成技术成熟，实验室和工业界能够生产与天然序列一致的合成版本。合成肽的纯度可达95%以上，并可通过反相高效液相色谱和质谱进行鉴定。这一转变使研究不再依赖动物胸腺来源。
市售的胸腺素α1通常以冻干粉形式提供，溶解后用于注射。其氨基酸组成包括多个酸性残基，因此在中性pH下带负电荷。该肽可溶于水和生理盐水，但在有机溶剂中溶解度有限。储存条件通常为冻干状态下负20摄氏度，溶解后需冷藏并避免反复冻融。常见的同义词包括胸腺肽α1、thymalfasin和Tα1。
Lyophilized thymosin alpha 1 is typically stored refrigerated at 2 to 8 degrees Celsius and kept away from light. Reconstituted solutions are less stable and are usually used promptly after preparation. Repeated freeze-thaw cycles are avoided because they can promote aggregation and loss of activity. The peptide adsorbs to some plastic and glass surfaces, so a carrier protein is often added to dilute working solutions. Manufacturer instructions and published protocols both govern handling.
Identity and purity testing for thymosin alpha 1 relies mainly on reversed-phase high-performance liquid chromatography and mass spectrometry. Chromatography separates the parent peptide from truncated or modified variants, while mass spectrometry confirms the expected molecular mass. Amino acid analysis and peptide mapping provide additional sequence confirmation. Counterion content, water content, and residual solvents are measured separately as part of specification testing. No single method captures every attribute, so laboratories combine several techniques.
== Medical uses == Tazarotene is most commonly used topically to treat acne vulgaris, psoriasis, and photoaging. Like other topical retinoids, such as tretinoin and adapalene, tazarotene can be used in a regimen with benzoyl peroxide and/or an oral antibiotic, such as clindamycin or dapsone, for the treatment of acne. This results in increased efficacy compared to tazarotene monotherapy. Combination therapy utilizing tazarotene alongside a mid- to high-potency corticosteroid is more effective in treating psoriasis compared to monotherapy of either drug. Tazarotene can also be used for the treatment of photodamaged skin. It can reduce the histological and clinical signs of photodamaged skin, such as fine lines, wrinkles, hyperpigmentation, and lentigo. The therapy is more effective when used with the daily application of sunscreen.
== Nonrennet coagulation == Many soft cheeses are produced without use of rennet, by coagulating milk with acid, such as citric acid or vinegar, or the lactic acid produced by soured milk. Cream cheese, paneer, rubing, and other acid-set cheeses are traditionally made this way. The acidification can also come from bacterial fermentation such as in cultured milk. Vegan alternatives to cheese are manufactured without using animal milk but instead use soy, wheat, rice or cashew. These can be coagulated with acid using sources such as vinegar or lemon juice.
== Recreational use == In 1979, the first case of xylazine toxicity was reported in a 34-year-old male who had self-medicated for insomnia with an injection of 1g of xylazine. In the US, Xylazine is not regulated as a controlled substance under the Controlled Substances Act. It is sold online through distributors often without requiring proof of a veterinary license. The cost to purchase Xylazine from overseas suppliers is around $6–20 per kilogram. This low price makes it attractive for dealers looking for a cheap additive that is addictive and not treatable with opiate withdrawal medications. The withdrawal can last for two weeks and has a quicker onset than fentanyl. As an adulterant, xylazine is most commonly ingested with fentanyl. Xylazine has also been reported in combination with medetomidine, another potent α2-adrenergic receptor agonist. It is unknown if drug users are ingesting it knowingly. As of 2024, Seattle police report that some users wrongly believe they are consuming higher-quality fentanyl. Xylazine's street name in Puerto Rico is anestesia de caballo, which translates to "horse anesthetic". From 2002 to 2008, its use was associated with a high number of inmate deaths at the Guerrero Correctional Institution in Aguadilla, Puerto Rico. Xylazine's street name in the United States, particularly when it is mixed with fentanyl, is "tranq", "tranq dope" and "zombie drug". As of 2012, xylazine users in Puerto Rico were more likely to be male, under age 30, living in a rural area, and injecting rather than inhaling xylazine.
Sources: en.wikipedia.org
== History == CPA was first synthesized in 1961 by Rudolf Wiechert, a Schering employee, and together with Friedmund Neumann in Berlin, they filed for a patent for CPA as "progestational agent" in 1962. The antiandrogenic activity of CPA was discovered serendipitously by Hamada, Neumann, and Karl Junkmann in 1963. Along with the steroidal antiandrogens benorterone (17α-methyl-B-nortestosterone; SKF-7690), cyproterone, BOMT (Ro 7–2340), and trimethyltrienolone (R-2956) and the nonsteroidal antiandrogens flutamide and DIMP (Ro 7–8117), CPA was one of the first antiandrogens to be discovered and researched. CPA was initially developed as a progestogen for the prevention of threatened abortion. As part of its development, it was assessed for androgenic activity to ensure that it would not produce teratogenic effects in female fetuses. The drug was administered to pregnant rats and its effects on the rat fetuses were studied. To the surprise of the researchers, all of the rat pups born appeared to be female. After 20 female rat pups in a row had been counted, it was clear that this could not be a chance occurrence. The rat pups were further evaluated and it was found that, in terms of karyotype, about 50% were actually males. The male rat pups had been feminized, and this resultant finding constituted the discovery of the powerful antiandrogenic activity of CPA. A year after patent approval in 1965, Neumann published additional evidence of CPA's antiandrogenic effect in rats; he reported an "organizational effect of CPA on the brain".
=== Cancer risk === Sirolimus may increase an individual's risk for contracting skin cancers from exposure to sunlight or UV radiation, and risk of developing lymphoma. In studies, the skin cancer risk under sirolimus was lower than under other immunosuppressants such as azathioprine and calcineurin inhibitors, and lower than under placebo.
is its oven dry mass (the attainment of constant mass generally after drying in an oven set at 103±2 °C (218±4 °F) for 24 hours as mentioned by Walker et al., 1993). The equation can also be expressed as a fraction of the mass of the water and the mass of the oven dry wood rather than a percentage. For example, 0.59 kg/kg (oven dry basis) expresses the same moisture content as 59% (oven dry basis).
Sources: en.wikipedia.org
It corresponds to a fragment of the larger protein prothymosin alpha, which is present in many tissues. The isolated 28-amino-acid peptide was originally obtained from thymus preparations, and the pharmaceutical product is synthesized rather than extracted. The term therefore describes both a natural fragment and a manufactured drug substance.
Thymosin alpha-1 is a single defined 28-residue peptide, while the broader family includes unrelated peptides such as thymosin beta-4. The shared name reflects historical isolation from thymus tissue rather than a common structure. Confusion between the two is common in older literature.
No single pathway fully accounts for its reported effects. Several studies describe interaction with innate immune receptors and downstream cytokine changes, but the complete picture is not settled. Open questions remain about which effects occur at physiological concentrations.
It is usually classified as an immunomodulatory peptide rather than a classical hormone. It derives from the larger protein prothymosin alpha and acts mainly on immune cells. The thymosin label covers a group of distinct peptides, so the naming can be misleading.