solid-phase synthesis 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 2025-12-21. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
The name itself causes confusion, because several unrelated thymic peptides share the thymosin label. Thymosin beta-4, for example, is a different molecule with different functions. Naming conventions in the literature also mix descriptive research terms with assigned nonproprietary names, so a reader should confirm which entity a given paper addresses. Clarifying that point is usually the first step in interpreting any claim about this peptide.
Thymosin alpha-1 is a 28-residue peptide first isolated from thymus tissue in the 1970s. It corresponds to the N-terminal portion of thymosin beta-4, from which it is cleaved in vivo. The peptide carries an acetyl group at its N-terminus, a modification that affects its charge and stability. Synthetic material produced by solid-phase peptide synthesis is chemically identical to the natural fragment and is the form used in research and clinical studies.
Laboratory work indicates that the peptide acts on cells of both the innate and adaptive immune systems. Reported effects include signalling through Toll-like receptors on dendritic cells, enhanced T-cell maturation, and increased natural killer cell activity. These actions are described largely from cell-culture and animal experiments, and the precise receptor-level events remain incompletely defined. Studies in humans have generally measured immune markers rather than a single defined molecular target. The resulting picture remains partly descriptive.
| Property | Value | Notes |
|---|---|---|
| Residue count | 28 amino acids | Acetyl group on the first residue |
| Approximate molecular mass | 3108 daltons | Calculated from the consensus sequence |
| Origin | Cleavage product of prothymosin alpha | Not encoded as a separate gene product |
| Primary research focus | Immune modulation | Studied in viral hepatitis and as a vaccine adjuvant |
| Common synonyms | Thymalfasin, Tα1, thymosin alpha 1 | Thymalfasin is the assigned nonproprietary name |
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography, which separates the peptide from closely related impurities and from truncated or oxidized variants. Mass spectrometry supplies the molecular mass and confirms the expected sequence length, while amino acid analysis can be used to check composition. Because the molecule has no chromophore beyond the peptide backbone, ultraviolet detection is typically performed at a low wavelength, where baseline interference from solvents and buffers is a practical concern. Water content and counter-ion content are often reported alongside purity.
Practical handling focuses on limiting adsorption and contamination. The peptide dissolves readily in water, and dilute solutions tend to adhere to plastic and glass surfaces, so an inert carrier protein or a defined buffer can reduce losses in laboratory work. Workers also record the counter-ion form, since an acetate or trifluoroacetate salt changes the mass balance of the weighed powder. Documentation of lot number, purity value, and storage history supports reproducibility when results from different laboratories are compared.
Thymosin alpha-1 is a synthetic peptide of 28 amino acids, corresponding to the N-terminal fragment of prothymosin alpha. Its sequence begins with acetylation at the N-terminus, a modification that affects stability and receptor interaction. The peptide is acidic, with a calculated isoelectric point near 4.2, and carries no disulfide bonds, so its secondary structure is largely flexible in solution. Molecular mass is approximately 3108 daltons. The native form was first isolated from bovine thymus tissue, while pharmaceutical material is produced by solid-phase peptide synthesis.
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.
== History == Approval by the US Food and Drug Administration (FDA) was based on TRIDENT-1, a global, multicenter, single-arm, open-label, multi-cohort clinical trial (NCT03093116) which included participants with ROS1-positive locally advanced or metastatic non-small cell lung cancer. Efficacy was evaluated in 71 ROS1 tyrosine kinase inhibitor-naïve participants who received up to one prior line of platinum-based chemotherapy and/or immunotherapy and 56 participants who received one prior ROS1 tyrosine kinase inhibitor with no prior platinum-based chemotherapy or immunotherapy. The FDA granted the application for repotrectinib priority review, breakthrough therapy, and fast track designations.
=== Children === In most countries, fluoroquinolones are only approved for use in children under narrowly defined circumstances, owing in part to the observation of high rates of musculoskeletal adverse events in fluoroquinolone-treated juvenile animals. The use of fluoroquinolones in those 18 years of age and under is only FDA approved for complicated UTI's (pyelonephritis and for postexposure prophylaxis) and treatment of inhalation anthrax. In the UK, the prescribing indications for fluoroquinolones for children are severely restricted. Only inhalational anthrax and pseudomonal infections in cystic fibrosis infections are licensed indications in the UK due to ongoing safety concerns. In a study comparing the safety and efficacy of levofloxacin to that of azithromycin or ceftriaxone in 712 children with community-acquired pneumonia, serious adverse events were experienced by 6% of those treated with levofloxacin and 4% of those treated with comparator antibiotics. Most of these were considered by the treating physician to be unrelated or doubtfully related to the study drug. Two deaths were observed in the levofloxacin group, neither of which was thought to be treatment-related. Spontaneous reports to the U.S. FDA Adverse Effects Reporting System at the time of the 20 September 2011 U.S. FDA Pediatric Drugs Advisory Committee included musculoskeletal events (39, including five cases of tendon rupture) and central nervous system events (19, including five cases of seizures) as the most common spontaneous reports between April 2005 and March 2008.
All FSL Kode constructs disperse in water and are therefore compatible with inkjet printers. FSL constructs can be printed with a standard desktop inkjet printer directly onto paper to create immunoassays. An empty ink cartridge is filled with an FSL construct and words, barcodes, or graphics are printed. A Perspex template is adhered to the surface to create reaction wells. The method is then a standard EIA procedure, but blocking of serum is not required and undiluted serum can be used. A typical procedure is as follows: add serum, incubate, wash by immersion, add secondary EIA conjugate, incubate, wash, add NBT/BCIP precipitating substrate and stop the reaction when developed by washing (Fig. 9). The result is stable for years.
Sources: en.wikipedia.org
=== Archives === Lt. John T. Alderson collection of Japan photographs Archived September 4, 2015, at the Wayback Machine. circa 1890s. 40 photographic prints (1 box) : hand colored; sizes vary. At the University of Washington Libraries, Special Collections.
=== Pyrimidine derivatives === Pyrimidine analogues are antimetabolites that interfere with nucleic acid synthesis. Some of them have been shown to fit the ATP-binding pocket of GSK-3β to lower blood glucose levels and improve some neuronal diseases.
The Serbian Revolution coincided with the Russo-Turkish War (1806–1812) (in which the French diplomat, Horace François Bastien Sébastiani de La Porta played a very important role in provoking the war), which were a proxy conflict of the Coalition Wars, having most of the time Serbs revolutionaries the support of the Russian Empire, while the Ottoman Empire was an ally of the French Empire. This was due to the fact that both empires feared Napoleon's moves to the east as the subsequent Peace of Pressburg brought France into Balkan affairs. The most radical and liberal rebels were also inspired in some way by the French Revolution (specially the rise of nationalism) and the autonomy of the Illyrian Provinces (Serbs initially felt that French presence in the region could have developed into military aid in support of the insurrection against Ottoman rule as a sister republic, but Napoleon didn't want to increase Russian or Austrian influence in the region).
=== MeSH D12.644.400 – neuropeptides === MeSH D12.644.400.070 – angiotensins MeSH D12.644.400.070.075 – angiotensin i MeSH D12.644.400.070.078 – angiotensin ii MeSH D12.644.400.070.080 – angiotensin iii MeSH D12.644.400.085 – bombesin MeSH D12.644.400.090 – bradykinin MeSH D12.644.400.095 – calcitonin MeSH D12.644.400.097 – calcitonin gene-related peptide MeSH D12.644.400.100 – carnosine MeSH D12.644.400.105 – cholecystokinin MeSH D12.644.400.120 – corticotropin MeSH D12.644.400.125 – corticotropin-releasing hormone MeSH D12.644.400.200 – delta sleep-inducing peptide MeSH D12.644.400.235 – fmrfamide MeSH D12.644.400.250 – galanin MeSH D12.644.400.275 – galanin-like peptide MeSH D12.644.400.300 – gastric inhibitory polypeptide MeSH D12.644.400.315 – gastrin-releasing peptide MeSH D12.644.400.320 – gastrins MeSH D12.644.400.340 – glucagon precursors MeSH D12.644.400.340.500 – glucagon MeSH D12.644.400.350 – gonadorelin MeSH D12.644.400.450 – motilin MeSH D12.644.400.460 – melanocyte-stimulating hormones MeSH D12.644.400.460.050 – alpha-msh MeSH D12.644.400.460.075 – beta-msh MeSH D12.644.400.460.115 – gamma-msh MeSH D12.644.400.465 – msh release-inhibiting hormone MeSH D12.644.400.470 – msh-releasing hormone MeSH D12.644.400.500 – neuropeptide y MeSH D12.644.400.525 – neurophysins MeSH D12.644.400.550 – neurotensin MeSH D12.644.400.575 – opioid peptides MeSH D12.644.400.575.180 – dynorphins MeSH D12.644.400.575.241 – endorphins MeSH D12.644.400.575.241.030 – alpha-endorphin MeSH D12.644.400.575.241.080 – beta-endorphin MeSH D12.644.400.575.241.360 – gamma-endorphin MeSH D12.644.400.575.281 – enkephalins MeSH D12.644.400.575.281.075 – enkephalin, ala(2)-mephe(4)-gly(5)- MeSH D12.644.400.575.281.231 – enkephalin, leucine MeSH D12.644.400.575.281.381 – enkephalin, methionine MeSH D12.644.400.575.281.600 – enkephalin, d-penicillamine (2,5)- MeSH D12.644.400.600 – pancreatic polypeptide MeSH D12.644.400.610 – peptide phi MeSH D12.644.400.625 – pituitary adenylate cyclase-activating polypeptide MeSH D12.644.400.640 – pituitary hormone release inhibiting hormones MeSH D12.644.400.645 – pituitary hormone-releasing hormones MeSH D12.644.400.680 – prolactin release-inhibiting hormone MeSH D12.644.400.700 – prolactin-releasing hormone MeSH D12.644.400.702 – thyrotropin-releasing hormone MeSH D12.644.400.705 – secretin MeSH D12.644.400.720 – somatostatin MeSH D12.644.400.740 – somatotropin-releasing hormone MeSH D12.644.400.800 – tachykinins MeSH D12.644.400.800.354 – eledoisin MeSH D12.644.400.800.475 – kassinin MeSH D12.644.400.800.500 – neurokinin a MeSH D12.644.400.800.550 – neurokinin b MeSH D12.644.400.800.625 – physalaemin MeSH D12.644.400.800.750 – substance p MeSH D12.644.400.875 – vasoactive intestinal peptide MeSH D12.644.400.900 – vasopressins MeSH D12.644.400.900.050 – argipressin MeSH D12.644.400.900.400 – lypressin MeSH D12.644.400.900.700 – oxytocin MeSH D12.644.400.900.900 – vasotocin
Sources: en.wikipedia.org
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.
The two share a family name but have different sequences, sizes, and functions. Thymosin beta-4 is a 43-residue peptide associated with actin binding and cell migration. Thymosin alpha-1 is a 28-residue peptide linked mainly to immune signaling.
Thymalfasin is the assigned international nonproprietary name for the synthetic 28-residue peptide. Thymosin alpha-1 is the descriptive research name for the same molecule. Which term appears depends on the context and the regulatory document.
It corresponds to the first 28 amino acids of thymosin beta-4, a larger protein found in many tissues. The fragment is acetylated at its N-terminus and is produced synthetically for research and pharmaceutical use. Synthetic and natural forms share the same sequence.