Thymagen

1 Identity

Declared synthetic dipeptide of the Khavinson short-peptide program. On the declared sequence it is a two-residue molecule with a free alpha-amino N-terminus, a free C-terminal acid, no cysteine, no disulfide and no non-proteinogenic residue. That class assignment rests entirely on a vendor and originator declaration and not on a monograph. If a supplier declares an extract under this name, the class assignment falls and the record moves to P7 with the extract line. The thymic member of the Khavinson "cytogen" line of defined synthetic short peptides, as distinct from the "cytomax" tissue-extract line. Widely cataloged alongside Vilon, Vesugen, Vesilut, Cartalax and Bronchogen.

Sequence

Declared, not confirmed: H-Glu-Trp-OH. The originating group's published entry lists Thymagen as Glu-Trp, and says in the same passage that the sequences of this family are as stated in vendor catalogs and in the group's own publications, with no independent check against a regulatory monograph. The declaration is therefore two-thirds of an identity statement and not the whole of one, because the string Glu-Trp names at least four distinct molecules: the glutamyl linkage may be alpha or gamma, and the glutamate may be L or D. Gamma-D-Glu-L-Trp is a separately developed compound sold as golotimod, CAS 229305-39-9, at institutional scale. Until a supplier fixes linkage and configuration in writing, this record does not assert which molecule the name denotes.

Molecular formula

C16H19N3O5 on the declared sequence, free acid. A mono-sodium salt C16H18N3NaO5 is the form registered in the Russian Federation for the same declared dipeptide under the adjacent trade name and may be offered here. The formula is arithmetic applied to a declaration; it is not independent evidence of what is in a vial, and no formula distinguishes the alpha from the gamma linkage or the L from the D glutamate.

Average mass

333.344 Da (C16H19N3O5, free acid), computed from the declared formula on IUPAC 2021 abridged conventional atomic weights (C 12.011, H 1.008, N 14.007, O 15.999). Mono-sodium salt C16H18N3NaO5, 355.326 Da; the free acid is 93.8 percent of the salt by mass, which is the correction a labeled-milligram figure needs and rarely gets.

Monoisotopic mass

333.13247 Da neutral (C16H19N3O5); [M+H]+ 334.13975; [M-H]- 332.12519. Mono-sodium salt 355.11441. A plus or minus 5 ppm window on [M+H]+ is plus or minus 0.0017 Da, which is easily met and proves almost nothing here, because the isomers that matter share the formula exactly.

Salt / variant note

The substitution problem here is the worst class in the catalog, because the leading confusable is not near the target, it is exactly isobaric with it, and it is a stocked catalog item. Same formula, same mass, different molecule: gamma-D-Glu-L-Trp, developed as SCV-07 and sold as golotimod, CAS 229305-39-9, C16H19N3O5, 333.344 / 333.13247, differing only in linkage and configuration, both invisible to mass spectrometry at any resolving power. Gamma-L-Glu-L-Trp, the regiochemical impurity produced by coupling through the side-chain carboxyl. Alpha-L-Glu-D-Trp and alpha-D-Glu-L-Trp, the chiral impurities. Trp-Glu, the reversed dipeptide. At least five molecules share 333.13247. Name collision within the catalog: Thymogen, declared as the same dipeptide, is carried as a separate record here, and no analytical result distinguishes the two names because the names are not analytical attributes. Mass-resolvable forms, each an arithmetic check a buyer can run: mono-sodium salt C16H18N3NaO5 355.326 / 355.11441; 1:1 trifluoroacetate-paired form C18H20F3N3O7 447.367 / 447.12533, of which the free acid is only 74.5 percent by mass; pyroGlu-Trp C16H17N3O4 315.329 / 315.12191, 18.01 Da light, the N-terminal cyclization product; oxidized tryptophan at plus 15.995 (C16H19N3O6, 349.343 / 349.12739) and plus 31.99 (C16H19N3O7, 365.342 / 365.12230); the kynurenine-type product at plus 3.995 (C15H19N3O6, 337.332 / 337.12739), a shift small enough to be dismissed as calibration noise; N-acetyl-Glu-Trp C18H21N3O6 375.381 / 375.14304 if the terminus was capped; and the unreacted starting materials, free L-Trp 204.229 / 204.08988 and free L-Glu 147.130 / 147.05316. Tryptophan is UV-bright at 280 nm, so residual free Trp distorts a purity figure read at the wrong wavelength. Cartalax, Ala-Glu-Asp, C12H19N3O8, is 333.297 average and 333.11721 monoisotopic, another peptide of the same program sold by the same vendors, 46 ppm away monoisotopic and identical to one decimal place on the average, so a certificate reading "333.3" has excluded neither.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definitionprovisional, with mandatory P3 chiral and regiochemical additions; it reverts to P7 if a supplier declares an extract rather than a synthetic single entity

3 Primary sources & evidence

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

Literature exists for the class and is recorded by study type, with no statement of what any member does. The index grades the family D: animal and in-vitro work plus non-independent, largely Russian-language reviews from the originating institution, with no independently replicated randomized human trial located. Named items: Khavinson VKh, Neuro Endocrinol Lett 2002, PMID 12374906, review; Khavinson V, Linkova N, Diatlova A, Trofimova S, Stem Cell Rev Rep 2020, PMID 31808038, review, and the source of the program's verbatim mechanistic claim about penetration of the cell and nuclear membranes; Khavinson VK, Kvetnoii IM, Bull Exp Biol Med 2000, PMID 11276315, rat study; Khavinson VKh, Kuznik BI, Ryzhak GA, Adv Gerontol 2012, PMID 23734519, review of experimental studies, and Adv Gerontol 2013, PMID 24003726, review of clinical reports rather than a primary randomized trial; Mironova ES et al., Adv Gerontol 2020, PMID 32593244, review. The index records the field's own objection to the program's central structural claim, that sequence-specific DNA recognition by a di- or tripeptide implies too few contacts to specify a unique genomic site, and notes that the claim has been advanced almost exclusively by one group over three decades. No publication located was conducted on a lot whose linkage and configuration were declared, which is why no citation here can be attached to a specific vial.

4 Storage & specification

Storage

The labeled condition is lyophilized white to off-white solid in the sealed original vial under foil overwrap or in amber glass, -20 degrees C plus or minus 5 degrees C, desiccated, protected from light. On the declared sequence this is among the most light-sensitive materials in the catalog: the single tryptophan is the oxidation- and photolysis-labile point of the molecule. Sampling is performed under yellow light and the sampling record captures cumulative light exposure, so that an out-of-specification oxidation result can be traced to handling rather than argued about.

Shelf life

The provisional retest interval is 24 months at -20 degrees C plus or minus 5 degrees C in the sealed original container protected from light, provisional pending the company's own stability data. Because tryptophan oxidation and N-terminal pyroglutamate formation are the two named degradation routes, the confirming study runs an ICH Q1B photostability arm alongside the long-term and accelerated arms, and the stability-indicating method must resolve pyroGlu-Trp at minus 18.011 Da and the plus 15.995 Da oxidation product from parent.