Thymosin A1 10 mg

Thymosin Alpha-1 — 10 mg

Purity: ≥98% (HPLC)
Form: lyophilized powder, 3 ml vial
Storage: −20 °C (before opening), +2…+8 °C (after reconstitution, no more than 28 days)
Verification: Janoshik Analytical (Czech Republic) — independent blind testing of every batch
Synonyms: Tα1, Thymalfasin, Thymosin alpha-1, Zadaxin (trade name)

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Contents

1. What is Thymosin Alpha-1?
2. Why Thymosin Alpha-1 attracts researchers' attention
3. Peptide structure
4. Immunomodulator, not immunostimulant — what is the difference
5. Mechanism of action — TLR and dendritic cells
6. Clinical studies and approvals
7. Thymosin Alpha-1 and Thymosin Beta-4 (TB-500) — do not confuse
8. Sources

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1. What is Thymosin Alpha-1?

Thymosin Alpha-1 (Tα1) is a 28-amino-acid peptide first isolated in 1977 by Allan Goldstein from an extract of calf thymus gland [1]. The thymus is the organ in which T-lymphocytes — the main "soldiers" of the adaptive immune system — mature. Thymosin Alpha-1 is one of the key signaling peptides that the thymus uses to manage the process of T-cell maturation.

The synthetic version of the peptide — thymalfasin — is marketed under the trade name Zadaxin. To date, it is the only thymic peptide that has completed a full cycle of clinical research, including Phase 3, and is approved as a medicinal product in more than 35 countries worldwide [2][3].

This makes Thymosin Alpha-1 unique in our catalog: it has one of the most substantial evidence bases among all research peptides — more than 30 randomized controlled trials involving over 11,000 patients.

For research use only. Not a medicinal product. Not intended for use in humans or animals.

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2. Why Thymosin Alpha-1 attracts researchers' attention

Thymosin Alpha-1 is of interest for several reasons, each of which is supported by clinical data:

• A modulator, not a stimulant. Unlike most immunotropic agents, Tα1 does not "rev up" the immune system in a single direction. It restores balance: strengthening a suppressed immune response and calming an excessive one [2][4]. This is fundamental: excessive stimulation of immunity can be just as dangerous as its deficiency.

• The thymus and age. The thymus is one of the first organs to "age": its involution begins as early as adolescence, and by age 50 it is largely replaced by fatty tissue. This is associated with the age-related decline in naive T-cells and the deterioration of adaptive immunity.

• Approved in 35+ countries. Zadaxin is registered in China, Italy, India, South Korea, the Philippines, Russia and a number of countries in Latin America and the Middle East — for chronic hepatitis B and as an immune adjuvant [3]. In the United States it holds Orphan Drug status for hepatitis B and hepatocellular carcinoma, but has not received full FDA approval.

• COVID-19. During the pandemic, Tα1 was used in several countries as an adjuvant therapy in severe forms of coronavirus infection. A retrospective analysis by Li et al. (2020) described a reduction in mortality in patients with severe lymphopenia [5].

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3. Peptide structure

Parameter	Value
Amino acid sequence	Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn
Number of amino acids	28
Molecular weight	3,108.43 Da
CAS number	62304-98-7
Type	Acetylated N-terminal fragment of prothymosin alpha
Origin	Thymus (thymus gland)
First isolation	Allan Goldstein, 1977
Trade name of synthetic version	Zadaxin (thymalfasin)

Thymosin Alpha-1 is the N-terminal fragment of the larger protein prothymosin alpha (109 amino acids). The synthetic molecule is fully identical to the endogenous peptide, which is one of the reasons for its high safety profile in clinical studies.

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4. Immunomodulator, not immunostimulant — what is the difference

This is the key distinction that defines Thymosin Alpha-1's place among immunotropic agents.

An immunostimulant (for example, high-dose IL-2) unconditionally increases immune activity. This can be useful in immunodeficiency, but is dangerous in autoimmune processes or chronic inflammation: stimulating an "overheated" system worsens the condition.

An immunomodulator works like a conductor: it does not increase the volume of the entire orchestra, but restores the balance between its sections. In experiments, Thymosin Alpha-1 [2][4]:

• In suppressed immunity — strengthens T-cell maturation, activates NK cells and dendritic cells
• In excessive activation — promotes the generation of regulatory T-cells (Treg), which restrain the inflammatory response
• Shifts the Th1/Th2 balance toward Th1 (cellular immunity) — which is important for antiviral and antitumor defense

It is precisely this bidirectionality — the ability both to strengthen and to calm — that makes Tα1 a subject of interest in the most varied clinical contexts: from viral infections to sepsis.

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5. Mechanism of action — TLR and dendritic cells

The molecular mechanism of Thymosin Alpha-1 has been studied in considerable detail.

The key target is the dendritic cells, the "scouts" of the immune system. They are the first to detect foreign agents and decide which type of response to launch. Tα1 interacts with the TLR2 and TLR9 receptors on the surface of dendritic cells [2].

The cascade then unfolds as follows:

1. TLR9 → activation of the MyD88 signaling pathway → IRF7
2. → Induction of the enzyme IDO (indoleamine 2,3-dioxygenase)
3. → IDO metabolizes tryptophan, creating a microenvironment that simultaneously activates effector T-cells and generates Treg
4. → Result: the immune response is activated, but balanced

The work of Romani et al. (2006), published in the journal Blood, describes this mechanism in detail at the level of dendritic cells [2]. It is precisely through the IDO-dependent pathway that Tα1 realizes its "bidirectional" immunomodulation.

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6. Clinical studies and approvals

Thymosin Alpha-1 has one of the most extensive clinical bases among all peptides:

Chronic hepatitis B

The main approved indication. In a meta-analysis of controlled studies, the combination of Tα1 + interferon-alpha showed a statistically significant increase in the rate of HBeAg seroconversion compared with interferon as monotherapy (RR 2.31; 95% CI 1.52–3.51) [3][6].

Immune adjuvant therapy

In studies, Tα1 increased the effectiveness of vaccination in the elderly and in immunocompromised patients — groups that traditionally respond poorly to standard vaccines [7].

Sepsis

A meta-analysis of randomized studies showed a reduction in mortality when Tα1 was added to standard therapy for severe sepsis. The data are heterogeneous, but the direction of the effect is consistent [3].

COVID-19

A retrospective analysis (Li et al., 2020) described a reduction in mortality in patients with severe lymphopenia who received Tα1 as an adjuvant to standard therapy [5].

Status by country

Region	Status
China, India, South Korea, Philippines	Approved (Zadaxin)
Italy	Approved
Russia	Approved
Latin America, Middle East	Approved in a number of countries
United States	Orphan Drug (hepatitis B, HCC), not approved by FDA
EU (EMA)	Not centrally approved

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7. Thymosin Alpha-1 and Thymosin Beta-4 (TB-500) — do not confuse

Despite the shared word "Thymosin" in the name, these are entirely different peptides:

Parameter	Thymosin Alpha-1	TB-500 (Thymosin Beta-4)
Length	28 amino acids	43 amino acids
Function	Immunomodulation	Tissue repair
Target	T-cells, dendritic cells, NK cells	Actin, cell migration
Clinical approvals	Yes (35+ countries)	No
Context in the LONGIVIYA catalog	Standalone product	Component of Blend Premium

Both peptides were isolated from the same source — the thymus, as part of the so-called "thymosin fraction 5." But these are different molecules with different sequences, mechanisms and areas of research.

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Sources

1. Goldstein A.L. et al. Thymosin alpha-1: isolation and sequence analysis of an immunologically active thymic polypeptide. Proc. Natl. Acad. Sci. USA, 74(2): 725–729, 1977. PubMed

2. Romani L. et al. Thymosin alpha-1 activates dendritic cell tryptophan catabolism and establishes a regulatory environment for balance of inflammation and tolerance. Blood, 108(7): 2265–2274, 2006. PubMed

3. Tuthill C. et al. Thymalfasin: biological properties and clinical applications. Curr. Pharm. Des., 6: 1–15.

4. Yang X. et al. Effect of thymosin alpha-1 on subpopulations of Th1, Th2, Th17 and regulatory T cells (Tregs) in vitro. Braz. J. Med. Biol. Res., 45(1): 25–32, 2012. PubMed

5. Li J. et al. Retrospective analysis of thymosin alpha-1 in COVID-19 patients with severe lymphopenia. Int. Immunopharmacol., 88: 106873, 2020. PubMed

6. Ciancio A., Marconi P. Thymosin alpha-1 in the treatment of chronic hepatitis B and C. Ann. N.Y. Acad. Sci., 1270: 127–133, 2012.

7. Panatto D. et al. Utility of thymosin alpha-1 (Zadaxin) as a co-adjuvant in influenza vaccines: a review. J. Prev. Med. Hyg., 52(3): 111–115, 2011.

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This material was prepared by the LONGIVIYA editorial team on the basis of published scientific research. The information is for educational purposes only and does not constitute a medical recommendation.

For research use only. Not a medicinal product. Not intended for use in humans or animals. Independent verification of every batch: Janoshik Analytical (Czech Republic).