Thymosin Alpha-1 (Tα1 / Thymalfasin)

✅ Synthetic 28-aa N-acetylated peptide (prothymosin α residues 2-29)
✅ TLR9 + TLR2 agonist; Th1-polarised T-cell maturation
✅ Clinically approved (Zadaxin) in 35+ countries for HBV / HCV
✅ Defined single-sequence peptide — distinct from multi-component Thymalin
✅ CAS 62304-98-7 (free) / 62304-94-3 (acetate); MW 3,108.3

Thymosin Alpha-1 contains synthetic 28-aa immunomodulatory research peptide.

Artikelnummer: Ej tillgängligt Kategori: Peptides Tagg: immune research peptide, research peptide, Th1 polarisation, Thymalfasin, Thymosin Alpha-1, TLR9 agonist, Tα1, Zadaxin

✓ Medically reviewed by Morgan Ellis — Pharmacy Researcher · 8 years experience · Last reviewed: May 2026

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Quick Answer — What is Thymosin Alpha-1?

Thymosin Alpha-1 (Tα1; clinically Thymalfasin / Zadaxin) is a synthetic 28-amino-acid peptide (CAS 62304-98-7 free, 62304-94-3 acetate; MW 3,108.3 g/mol) corresponding to the N-terminal 28 residues of the natural thymus-derived prothymosin precursor. 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-OH. Mechanism: activates TLR9 and TLR2 on dendritic cells and macrophages, drives Th1-polarised T-cell maturation, increases CD4+ and CD8+ T-cell proliferation, and enhances IFN-γ / IL-2 cytokine production. Clinically approved in 35+ countries (under brand Zadaxin) for chronic hepatitis B and C, and used as immune-support adjuvant in oncology research. For laboratory research use only. Defined single-sequence 28-aa peptide — distinct from the multi-component Thymalin polypeptide preparation.

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Specification	Detail
Compound Class	Synthetic 28-aa immunomodulatory peptide (prothymosin α N-terminal fragment); TLR9/TLR2 agonist; defined single-sequence thymic peptide
Chemical Name	Thymosin Alpha-1 (synonyms: Tα1, Thymalfasin, Zadaxin)
CAS Number	62304-98-7 (free peptide); 62304-94-3 (acetate salt)
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-OH (28 amino acids; N-terminal acetylation; corresponds to residues 2–29 of prothymosin α)
Molecular Weight	3,108.3 g/mol
Molecular Formula	C₁₂₉H₂₁₅N₃₃O₅₅; MW 3108.32 g/mol (28-aa N-terminal acetylated peptide, free acid C-terminus).
Mechanism	Activates TLR9 (toll-like receptor 9) on dendritic cells and plasmacytoid DCs, with secondary TLR2 engagement. Downstream effects: MyD88-IRAK-NF-κB signalling cascade; Th1-polarised T-cell maturation; increased CD4+ / CD8+ T-cell proliferation; enhanced IFN-γ and IL-2 production; activated NK cell cytotoxicity; modulation of regulatory T-cell (Treg) balance. Net effect is broad immune-restoration / Th1-enhancement.
Form / Purity / Storage	Lyophilized white-to-off-white powder, ≥99% HPLC. Store 2–8 °C short-term, −20 °C long-term. Reconstituted: 2–8 °C, use within 30 days. Avoid freeze-thaw.
Research Use	For laboratory research use only. Zadaxin (clinical Tα1) is approved in 35+ countries for chronic HBV and HCV (not FDA-approved in the US). Not on the WADA Prohibited List.

Mechanism of Action — TLR9 / TLR2 Activation + Th1 Polarisation

Thymosin Alpha-1 is a defined-sequence immune-modulating peptide with extensive characterised mechanism in published research:

TLR9 agonism on dendritic cells — Tα1 binds TLR9 (an endosomal pattern-recognition receptor normally activated by CpG-DNA motifs) on dendritic cells and plasmacytoid DCs, triggering MyD88 → IRAK → NF-κB signalling. This produces a DC-maturation phenotype with upregulated MHC class II, CD80, CD86 co-stimulatory molecules.
Secondary TLR2 engagement — Lower-affinity TLR2 binding on macrophages and DCs contributes additional pro-inflammatory cytokine output.
Th1-polarised T-cell maturation — Mature TLR9-activated DCs prime CD4+ T cells toward Th1 differentiation; IL-12 from activated DCs is the key Th1-polarising signal.
CD4+ and CD8+ T-cell expansion — Tα1-treated cohorts show measurable increase in circulating CD4+ and CD8+ T cells with reduced CD4+/CD8+ ratio normalisation.
NK-cell cytotoxicity enhancement — IL-12-driven NK activation produces increased IFN-γ output and enhanced tumour-cell / virus-infected-cell killing.
Regulatory T-cell (Treg) modulation — Published research has documented Tα1-mediated effects on Treg homeostasis with reduced FoxP3+ Treg proportion in chronic-infection contexts.

Published Research Applications

Chronic HBV and HCV research — most-published clinical application; Zadaxin approved in 35+ countries for these indications
Oncology immune-support research — used in published research as immunoadjuvant in melanoma, hepatocellular carcinoma, lung cancer protocols
HIV / immunosuppressed-host research — CD4+ T-cell expansion in published HIV-research contexts
Sepsis / severe-infection immune-modulation research — Tα1 has been investigated in sepsis-immunoparalysis reversal research
TLR9 pharmacology — Tα1 is one of the canonical peptide TLR9 agonists alongside CpG ODNs
Vaccine-adjuvant research — Th1-polarising adjuvant utility

For related research peptides see Thymalin (multi-component thymic extract — Khavinson bioregulator class), LL-37 (innate-immunity antimicrobial peptide), Epitalon (Khavinson pineal bioregulator). Browse the full peptide research catalog.

Available Strengths

Vial Strength	Pack Sizes
5 mg — standard research; matches Zadaxin clinical-vial-size pattern	10 or 20 vials
10 mg — extended-protocol or high-dose research; lowest per-mg cost	10 or 20 vials

How It Compares — Thymosin Alpha-1 vs Thymalin

Both are thymic immune peptides. Thymosin Alpha-1 is a defined single-sequence 28-amino-acid peptide (CAS 62304-98-7) with well-characterised TLR9/TLR2 mechanism. Thymalin is a multi-component polypeptide preparation extracted from thymic tissue — containing multiple short oligopeptides whose individual sequences vary slightly between batches. For research requiring defined-sequence pharmacology, Thymosin Alpha-1 is the cleaner tool. For research requiring the broader Khavinson-bioregulator-class effect of thymic-extract preparations, Thymalin is the choice.

💧 Need BAC water? Reconstituting any lyophilized vial requires sterile bacteriostatic water. Pair this product with our BAC Water (Bacteriostatic Water) — 30 mL multi-dose vial, 0.9% benzyl-alcohol-preserved, USP-grade.

Storage and Reconstitution

Store lyophilized vials at 2–8 °C short-term, −20 °C long-term. Reconstitute with bacteriostatic water (1.0 mL per 5 mg vial → 5 mg/mL; 1.0 mL per 10 mg vial → 10 mg/mL). Swirl gently. Store reconstituted at 2–8 °C, use within 30 days.

FAQ

What is the difference between Thymosin Alpha-1 and Thymalin?

Thymosin Alpha-1 is a defined synthetic 28-aa peptide with characterised TLR9/TLR2 mechanism. Thymalin is a multi-component thymic tissue extract preparation. See the comparison section above.

Is Thymosin Alpha-1 FDA-approved?

Zadaxin (clinical Thymalfasin) is approved in 35+ countries (China, Italy, others) for chronic HBV and HCV — but is NOT FDA-approved in the US.

What dose ranges are used in research?

Clinical Zadaxin dosing is 1.6 mg SC twice weekly for 6 months in HCV/HBV protocols. Rodent in-vivo research uses 50–200 µg/kg SC. In-vitro DC stimulation typically uses 0.1–10 µg/mL.

Can Thymosin Alpha-1 be combined with other immune peptides?

Yes — published research has examined Tα1 + IFN-α (HCV protocols), Tα1 + checkpoint inhibitors (oncology research), and Tα1 + Thymalin or LL-37 for broader immune-modulation work.

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Other Immune / Anti-Microbial Research Peptides

Thymalin — Multi-component Khavinson-class thymic polypeptide preparation
LL-37 (Cathelicidin) — Innate-immunity antimicrobial peptide
Epitalon — Khavinson pineal-axis tetrapeptide
Selank — Anxiolytic + immune-modulating Russian peptide
BPC-157 — Tissue-repair pentadecapeptide
BAC Water (Bacteriostatic Water) — Required for reconstituting any lyophilized vial — sterile, 0.9% benzyl-alcohol-preserved diluent