Thymalin

1 Identity

Compositionally undefined animal-tissue extract. Described in the peer-reviewed literature as "an immunomodulatory drug containing a polypeptide extract of thymus" (PMID 37686182) and elsewhere as a "Thymalin peptide complex" (PMID 35408963); the source animal is bovine or calf. Associated work attributes part of the preparation's reported activity to short peptides including Lys-Glu and Glu-Trp, but the full composition of the preparation is not publicly defined. It is not a defined peptide and cannot be characterized by sequence, and vendor descriptions presenting it as a characterized peptide with a known sequence are describing something that does not exist in the published record. and as a thymus polypeptide extract preparation associated with the St Petersburg Institute of Bioregulation and Gerontology. No CAS number is printed for it. Not synonyms, and the confusion is commercially systematic: Thymogen and Thymagen, the program's declared synthetic dipeptide Glu-Trp, and Vilon.

Sequence

No defined sequence exists and none can be stated. The literature describes a polypeptide extract, not a molecule. Two named dipeptides recur in the associated publications as constituents of interest, Lys-Glu and Glu-Trp, and both are separately defined single entities with their own records in this catalog; naming them does not define the preparation, because their proportion, the identity of everything else present and the chain-length distribution are all undeclared. An extract has a molecular-weight distribution, not a sequence.

Molecular formula

None. Not applicable to an undefined extract, and not verifiable in principle rather than merely unverified. A refusal is printed here rather than a blank, because a blank reads as an omission and the absence is the finding.

Average mass

None, and none is determinable. There is no single molecular species, so no molecular weight exists to be measured; a mixture has a distribution. The two constituent dipeptides named in the literature do have masses of their own. Lys-Glu C11H21N3O5, 275.305 Da; Glu-Trp C16H19N3O5, 333.344 Da. Those are the masses of two named molecules that are reported to be present, not the mass of this article.

Monoisotopic mass

None, for the same reason: a monoisotopic mass is a property of one molecular formula and there is no formula. For the two named constituents: Lys-Glu 275.14812 Da; Glu-Trp 333.13247 Da. A certificate for this preparation reporting either figure as the identity of the article is a certificate for a different, defined article.

Salt / variant note

The arithmetic runs backwards here as it does for every P7 record, and a buyer should read a clean certificate as disproof. Any document for this name bearing a single molecular weight, a molecular formula, a sequence or a purity percentage is describing a different article or was written to look like a certificate. What could be shipped instead, with every figure computed on the IUPAC 2021 abridged table. Defined molecules of the same program, which do have masses: Glu-Trp C16H19N3O5, 333.344 / 333.13247; Lys-Glu C11H21N3O5, 275.305 / 275.14812; Epitalon Ala-Glu-Asp-Gly C14H22N4O9, 390.349 / 390.13868; Vesugen reported Lys-Glu-Asp C15H26N4O8, 390.393 / 390.17506; Cartalax Ala-Glu-Asp C12H19N3O8, 333.297 / 333.11721. Note two traps: Epitalon and Vesugen are 0.0364 Da apart monoisotopic, 93 ppm, and identical to one decimal on the average; Cartalax and Glu-Trp are 0.0153 Da apart, 46 ppm, and both round to 333.3. Defined thymic molecules from the adjacent naming cluster: thymosin alpha-1 C129H215N33O55, 3108.315 / 3106.50413; thymopentin C30H49N9O9, 679.776 / 679.36532; thymosin beta-4 C212H350N56O78S, 4963.506 / 4960.48632; TB-500 Ac-LKKTETQ C38H68N10O14, 889.018 / 888.49165. Four articles whose names differ by one syllable and whose masses differ by an order of magnitude. Extract for extract, the substitution nobody can detect: the program's pineal, testicular, vascular, hepatic, cartilage and retinal preparations are lyophilized powders with no declared analyte, and no certificate result distinguishes a thymic extract from a testicular one, because there is no measured attribute on which they differ. Species substitution: bovine versus porcine thymus is a PCR or peptide-mass-fingerprint question that nobody in this channel runs, and it is the question that matters most.

2 Class & testing panel

Form

Single article

Testing panel

P7 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Literature exists, is recorded by study type, and is not summarized as any effect. In vitro: PMID 35408963, Int J Mol Sci 2022, human THP-1 monocyte/macrophage line; PMID 37686182, Int J Mol Sci 2023, human blood cells, studying the constituent dipeptides Lys-Glu and Glu-Trp rather than the preparation; PMID 33237528, Bull Exp Biol Med 2020, human hematopoietic stem cells. Animal: PMID 38431810, Wiad Lek 2024 and PMID 38642352, Pol Merkur Lekarski 2024, both rat mandibular-defect models. Human: PMID 36169363, Adv Gerontol 2022, an explicitly non-randomized observational comparison in severe COVID-19; PMID 12577695 and PMID 12447484, Adv Gerontol 2002; PMID 3839953, Vopr Onkol 1985; PMID 6547012, Vestn Khir 1984, the last two Soviet-era clinical reports predating modern trial-reporting standards. No randomized controlled trial was identified and no NCT registration was located; the finding is that none was located, not that none exists. The index grades the evidence D and records that it does not reach C because there is no adequately controlled human study of any size, that essentially the whole literature originates from or is closely associated with one group, and that it is effectively unreplicated by independent investigators. Two safety-side absences are recorded as absences: no immunogenicity data and no carcinogenicity assessment were identified, and because the composition is undefined, an adverse finding could not be attributed to a specific molecule and lot-to-lot equivalence cannot be demonstrated.

4 Storage & specification

Storage

Lyophilized powder at -20 degrees C or below, protected from light and moisture, in sealed vials that are equilibrated to room temperature before opening. As an animal-tissue-derived material it is handled under the SOP for that class, with the species and the country of origin recorded on the goods-receipt note. The temperature and the light and moisture controls follow the general laboratory practice for lyophilized protein and peptide extracts; because the composition is undefined they are a handling convention rather than a stability conclusion.

Shelf life

No stability-derived retest interval is set. A retest interval states that a measured property has been shown to hold over time; this preparation has no analyte to hold constant, and no stability-indicating method can exist for a mixture of undefined composition. Each container is therefore dated from receipt, and the attributes that limit that date are the physical ones an extract can be held to — appearance, moisture and closure integrity — rather than any purity or potency figure.