PT-141 vs Thymosin Alpha-1
Specialty
PT-141
Cyclic heptapeptide melanocortin receptor agonist, a metabolite of melanotan II studied for central MC4R signaling.
Specialty
Thymosin Alpha-1
28-amino-acid thymic peptide studied for Toll-like receptor signaling and T-cell maturation.
Side by side
| Dimension | PT-141 | Thymosin Alpha-1 |
|---|---|---|
| Molecular weight A 3.0× difference in mass — these are not comparable on a milligram-for-milligram basis. | 1025.16 g/mol | 3108.3 g/mol |
| Size class | short peptide | mid-length peptide |
| CAS number | 189691-06-3 | 62304-98-7 |
| Research area | specialty | specialty |
| Sequence | Not published as a linear sequence | Not published as a linear sequence |
| Available sizes | 10mg | 10mg |
| Entry price | $44 | $59 |
| Cost per mg | $4.40 | $5.90 |
Mechanism
PT-141
PT-141 is a cyclic heptapeptide and the deaminated metabolite of melanotan II, acting as an agonist at melanocortin receptors with principal research interest at MC4R. Unlike melanotan II it lacks significant MC1R-mediated pigmentation activity, making it a cleaner tool for isolating MC4R-mediated central effects. Its mechanism is centrally mediated rather than vascular, which distinguishes it from PDE5-targeting compounds.
Thymosin Alpha-1
Thymosin alpha-1 is a 28-amino-acid N-terminally acetylated peptide originally isolated from thymic tissue. It is among the better-characterized immunomodulatory peptides, with published mechanism centering on TLR2 and TLR9 signaling in dendritic cells and downstream effects on T-cell differentiation. Unlike much of this catalog, it has an established clinical literature under the name thymalfasin.
Evidence quality
Mechanism is not the same as evidence. Where we have assessed the literature, the verdict is stated plainly.
PT-141
Evidence base: strong by the standards of this catalogue. Randomised phase 3 trials, a published pooled safety analysis, and regulatory approval for a defined indication. The evidence supports the studied endpoint and population, not a general claim.
Full research reference →Thymosin Alpha-1
Evidence base: the largest and highest-quality in this catalogue after the incretin compounds. Multiple approved indications and a 2025 randomised phase 3 sepsis trial. The modulatory mechanism is context-dependent and correspondingly harder to interpret than a simple agonist relationship.
Full research reference →Research applications
PT-141
- MC4R and MC3R binding and selectivity assays
- Central melanocortin pathway signaling studies
- Comparative receptor profiling against melanotan II
Thymosin Alpha-1
- TLR2 and TLR9 signaling assays in dendritic cell culture
- T-cell maturation and differentiation studies
- Cytokine profiling (IL-2, IFN-γ) in immune models
- Vaccine adjuvant research
Common questions
What is the difference between PT-141 and Thymosin Alpha-1?
PT-141 is cyclic heptapeptide melanocortin receptor agonist, a metabolite of melanotan II studied for central MC4R signaling. Thymosin Alpha-1 is 28-amino-acid thymic peptide studied for Toll-like receptor signaling and T-cell maturation. They differ in molecular weight (1025.16 vs 3108.3 g/mol) and in the pathways they are studied against.
Which is more cost-effective per milligram, PT-141 or Thymosin Alpha-1?
PT-141 is lower at approximately $4.40 per milligram at its best tier, against $5.90 for the other. Cost per milligram is only meaningful relative to the concentrations a given protocol requires, since these compounds are not used at comparable masses.
Can PT-141 and Thymosin Alpha-1 be studied together?
Combination designs appear in the published literature for a number of these compounds. Whether it is appropriate for a given protocol depends entirely on the model and endpoint. We supply research compounds and do not provide protocol guidance — consult the primary literature for your specific model.
How should PT-141 and Thymosin Alpha-1 be stored?
Store lyophilized at -20°C protected from light. Reconstituted at 2-8°C for up to 30 days. For Thymosin Alpha-1: Store lyophilized at -20°C protected from light. Reconstituted at 2-8°C for up to 30 days.
Which has the stronger evidence base?
PT-141 — Evidence base: strong by the standards of this catalogue. Randomised phase 3 trials, a published pooled safety analysis, and regulatory approval for a defined indication. The evidence supports the studied endpoint and population, not a general claim. Thymosin Alpha-1 — Evidence base: the largest and highest-quality in this catalogue after the incretin compounds. Multiple approved indications and a 2025 randomised phase 3 sepsis trial. The modulatory mechanism is context-dependent and correspondingly harder to interpret than a simple agonist relationship.
All products sold on this website are intended for research and identification purposes only. These products are not intended for human dosing, injection, or ingestion.
Comparison generated from Lyra Vital catalog data. Every specification is reconciled against the certificate of analysis for the shipped batch.