This is a working overview of thymalfasin, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-02 and is reviewed periodically as new material appears.
The peptide was identified during work in the 1970s on thymosin fraction 5, a partially purified extract of calf thymus. Investigators separated that mixture and characterized individual components, one of which they named thymosin alpha-1. The same compound later received the international nonproprietary name thymalfasin. Commercial material is produced by solid-phase peptide synthesis rather than by extraction, so synthetic and natural forms share an identical sequence. Naming conventions vary across the literature, and readers should distinguish the alpha-1 peptide from other thymosins that have unrelated sequences and functions.
Thymosin beta-4 is a separate 43-residue peptide that binds actin and participates in cell migration; it shares no sequence similarity with thymosin alpha-1 despite the common family name. Other preparative materials, such as thymosin fraction 5 and thymopoietin, contain distinct mixtures or peptides. The shared thymosin label reflects the tissue of origin used in early purification, not a common structural core. Treating these molecules as interchangeable is a frequent source of confusion in laboratory reports and in popular summaries alike.
Thymosin alpha-1 is a synthetic peptide of 28 amino acid residues that corresponds to a naturally occurring fragment first isolated from thymus tissue. Its chain is acetylated at the amino terminus, a modification that shields the peptide from rapid cleavage by aminopeptidases. The molecule carries a net negative charge at physiological pH and dissolves freely in water. Researchers classify it as an immune-modulating agent rather than a classical hormone, because it acts on several cell types of both the innate and the adaptive immune system.
Thymosin alpha-1 is supplied as a lyophilized powder in most research settings. The solid dissolves readily in water and in common aqueous buffers, and it is typically reconstituted shortly before use. Solutions are clear and colourless at ordinary working concentrations. Because the peptide is hygroscopic, weighing and reconstitution are usually performed with minimal exposure to ambient air. Aliquots are prepared to avoid repeated freeze-thaw cycles, and working solutions are kept cold.
Long-term storage is generally at minus twenty degrees Celsius or colder, preferably desiccated and protected from light. Lyophilized material is more stable than reconstituted solution, which degrades faster at room temperature. Stability depends on pH, ionic strength, and the presence of oxidising agents. Published stability data for the peptide are limited, so storage claims in catalogues should be treated as general guidance rather than measured guarantees. Freeze-thaw cycles are kept to a minimum.
Identity and purity are normally confirmed by reversed-phase high-performance liquid chromatography and mass spectrometry. The expected mass for the acetylated 28-residue peptide is close to 3108 daltons, and a mass shift indicates a modification or truncation. Peptide mapping after enzymatic digestion can resolve sequence-level questions. Counter-ion content, water content, and residual solvents are separate quality attributes that a certificate of analysis may or may not report. Aggregation is monitored by size-exclusion chromatography when relevant.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | About 3.1 kDa | 28 residues, N-terminally acetylated |
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in aqueous buffers |
| Storage temperature | 2 to 8 °C | Protect from light and moisture |
| Common synonyms | Thymalfasin; Tα1 | Same peptide sequence |
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.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
Several names appear in the literature for this peptide, including thymalfasin and the abbreviation T-alpha-1. Naming conventions differ among research articles, regulatory documents, and supplier catalogs, which complicates literature searches. Both synthetic and recombinant production routes yield a peptide with the same 28-residue sequence as the thymic isolate. Because the thymosin label also covers unrelated peptides, sources should be compared by sequence rather than by name alone.
Whether the free 28-residue peptide circulates in human tissue remains debated. The best-documented human source is prothymosin alpha, a larger acidic protein that carries the sequence at its N-terminus. Reports of measurable peptide levels in serum and lymphoid tissue exist, yet some of that signal may come from cross-reacting fragments or from the parent protein. Most reviews therefore treat prothymosin alpha as the established human molecule and describe independent circulation of the small peptide as an unresolved question.
Immunological studies connect the peptide to multiple parts of the immune response. It has been reported to engage Toll-like receptor signaling, to promote dendritic cell maturation, and to influence the balance of T helper cell subsets. Changes in natural killer cell activity and in cytokine release appear in cell culture and animal models. These observations describe broad immunomodulatory behavior rather than a single defined receptor target, and the primary molecular interaction has not been settled.
β-Lactams may form an adduct E-I* of high stability with DD-transpeptidase. The half life of this adduct is around hours, whereas the half-life of the normal reaction is in the order of milliseconds. The interference with the enzyme processes responsible for cell wall formation results in cellular lysis and death due to the triggering of the autolytic system in the bacteria.
== Properties == Bromine is the third halogen, being a nonmetal in group 17 of the periodic table. Its properties are thus similar to those of fluorine, chlorine, and iodine, and tend to be intermediate between those of chlorine and iodine, the two neighbouring halogens. Bromine has the electron configuration [Ar]4s23d104p5, with the seven electrons in the fourth and outermost shell acting as its valence electrons. Like all halogens, it is thus one electron short of a full octet, and is hence a strong oxidising agent, reacting with many elements in order to complete its outer shell. Corresponding to periodic trends, it is intermediate in electronegativity between chlorine and iodine (F: 3.98, Cl: 3.16, Br: 2.96, I: 2.66), and is less reactive than chlorine and more reactive than iodine. It is also a weaker oxidising agent than chlorine, but a stronger one than iodine. Conversely, the bromide ion is a weaker reducing agent than iodide, but a stronger one than chloride. These similarities led to chlorine, bromine, and iodine together being classified as one of the original triads of Johann Wolfgang Döbereiner, whose work foreshadowed the periodic law for chemical elements. It is intermediate in atomic radius between chlorine and iodine, and this leads to many of its atomic properties being similarly intermediate in value between chlorine and iodine, such as first ionisation energy, electron affinity, enthalpy of dissociation of the X2 molecule (X = Cl, Br, I), ionic radius, and X–X bond length.
Minoxidil — first-line, low dose topical drug for hair loss, can also be used orally at a high dose for hypertension; oral minoxidil has been implicated in heart problems including pericardial effusion. Monoamine oxidase inhibitors — used for treatment-resistant depression; may have potentially lethal dietary and drug interactions which may trigger hypertensive crisis and/or serotonin syndrome. Thalidomide — originally prescribed for morning sickness, withdrawn in 1961 owing to widespread incidence of severe birth defects (phocomelia or tetraamelia) after prenatal use by pregnant women; approved by the US Food and Drug Administration for erythema nodosum leprosum (ENL) in 1998, and new cases of multiple myeloma (administered with dexamethasone) in 2008; also used "off-label" for rare cancers; can cause multiple severe side effects and cannot be prescribed to pregnant women. Tolcapone — used in patients with Parkinson's disease who are not appropriate candidates for other adjunctive therapies; use is restricted due to hepatotoxicity. Vigabatrin — used for extreme treatment-resistant epilepsy; carries risk of permanent vision loss.
Sources: en.wikipedia.org
From the beginning of the Gaza war, reports emerged of children being killed and maimed. Children were also killed in Israeli airstrikes, including in areas designated as “safe zones” by the IDF. The numbers rose rapidly. During the first week of the war in October 2023, at least 447 children were killed. By 3 December 2023, the number had reached an estimated 6,150 children, rising to about an estimated 10,000 by mid-January 2024, with thousands more believed to be buried under rubble. Defense for Children International put the figure at 12,100 children in early February, and mid-April 2024 estimates cited around 14,500 fatalities. In May 2024, the United Nations adjusted its estimate down from 14,500 children to 7,797 identified child deaths, and by December 2024, the overall figure was again reported at roughly 14,500. By 3 September 2025, at least 19,424 children had been reported killed. In March 2024, the United Nations stated that more children had died in Gaza between October 2023 and February 2024 than the sum of all global conflicts from 2019 to 2022. Catherine M. Russell, the head of UNICEF, stated, "We haven’t seen that rate of death among children in almost any other conflict in the world". In late September 2024, Oxfam and Action on Armed Violence reported that the number of children killed in Gaza over the past year was the highest recorded in a single year for any conflict worldwide in the last 20 years.
=== Pharmacokinetics === Variations in ADME, i.e. an individual's efficiency in absorbing, tissue-distributing, metabolizing, or excreting a drug, have been found to occur in various severe cutaneous adverse reactions (SCARS) as well as other types of adverse drug reactions. These variations influence the levels and duration of a drug or its metabolite in tissues and thereby impact the drug's or metabolite's ability to evoke these reactions. For example, CYP2C9 is an important drug-metabolizing cytochrome P450; it metabolizes and thereby inactivates phenytoin. Taiwanese, Japanese, and Malaysian individuals expressing the CYP2C9*3 variant of CYP2C9, which has reduced metabolic activity compared to the wild type (i.e. CYP2c9*1) cytochrome, have increased blood levels of phenytoin and a high incidence of SJS (as well as SJS/TEN and TEN) when taking the drug. In addition to abnormalities in drug-metabolizing enzymes, dysfunctions of the kidney, liver, or GI tract which increase a SCARs-inducing drug or metabolite levels are suggested to promote SCARs responses. These ADME abnormalities, it is also suggested, may interact with particular HLA proteins and T cell receptors to promote a SCARs disorder.
Each neurotransmitter has very specific degradation pathways at regulatory points, which may be targeted by the body's regulatory system or medication. Cocaine blocks a dopamine transporter responsible for the reuptake of dopamine. Without the transporter, dopamine diffuses much more slowly from the synaptic cleft and continues to activate the dopamine receptors on the target cell.
Sources: en.wikipedia.org
It is a 28-residue synthetic peptide studied as an immune-modulating agent and approved as a drug in some countries. The sequence matches a naturally occurring fragment isolated from thymus tissue. It is not a hormone in the endocrine sense.
The name traces back to thymosin fraction 5, a crude thymus extract examined in the 1970s. Individual peptides in that mixture were labeled with Greek letters, and alpha-1 was one of them. The international nonproprietary name thymalfasin was assigned later.
No. Thymosin beta-4 contains 43 residues and binds actin, while thymosin alpha-1 contains 28 residues and acts on immune cells. The two sit in a historical naming group but share no sequence similarity, and they are not substitutes for one another.
Lyophilized powder is normally kept at minus twenty degrees Celsius or below, in a sealed container, desiccated and away from light. Reconstituted solutions are less stable and are usually refrigerated and used quickly. Repeated temperature cycling should be avoided.