Livagen

1 Identity

Short-chain bioregulator (Khavinson peptides). Synthetic linear all-L tetrapeptide of four proteinogenic residues. The name is a trade name from the Khavinson short-peptide bioregulator program; the commercial terms "cytogen" and "peptide bioregulator" describe the program, not the molecule, and are not identity statements. No CAS number is asserted: CAS varies by peptide across this class and none is independently verified for it. Same-program names sitting on the same shelf are different articles, each with its own mass, and they are enumerated in the salt and variant note below.

Sequence

H-Lys-Glu-Asp-Ala-OH; one-letter KEDA, four residues, free acid. All-L, entirely proteinogenic. Free N-terminal alpha-amine, free lysine epsilon-amine, two free side-chain carboxyls (Glu2, Asp3), free C-terminal carboxylic acid. No amidation, no acetylation, no acylation, no cysteine and therefore no disulfide, no methionine, no tryptophan, no tyrosine and no aromatic residue at all, which has a direct analytical consequence: 280 nm is not a valid detection wavelength for this article. The sequence is an attribution, not A verified structure: it is taken from vendor catalogs and from the originating group's own publications, and those sequences have not been verified against a regulatory monograph; formula, molecular weight and CAS are not independently verified anywhere in this class. Everything downstream of the sequence in this record is exact; the sequence itself is a commercial attribution and is flagged as such wherever it is relied on. The arithmetic that follows reproduces exactly, and reproducing it confirms the arithmetic and not the compound.

Molecular formula

C18H31N5O9 (free acid, on the KEDA attribution). Mono-acetate C20H35N5O11; mono-trifluoroacetate C20H32F3N5O11; bis-acetate C22H39N5O13. Aspartyl succinimide intermediate C18H29N5O8. C-terminal amide C18H32N6O8.

Average mass

461.472 Da (C18H31N5O9), on IUPAC 2021 abridged conventional atomic weights. A value of 461.467 also circulates; the formula gives 461.472, and the small spread is an atomic-weight revision rather than an unexplained discrepancy. Salt forms: mono-acetate 521.52, of which 11.5 percent of the gross weight is acetate; mono-trifluoroacetate 575.49, of which 19.8 percent is trifluoroacetate. On a 461 Da tetrapeptide with two basic sites the counterion is a first-order quantity and not a rounding adjustment: a vial certified as 20 mg of "Livagen" with no net peptide number can hold 16 mg of peptide. Succinimide intermediate 443.46, which is 18.01 Da lighter. C-terminal amide 460.49, which is 0.98 Da lighter.

Monoisotopic mass

461.21218 Da neutral (C18H31N5O9). [M+H]+ 462.21946; [M+2H]2+ 231.61337; [M-H]- 460.20490. Succinimide intermediate 443.20161. C-terminal amide 460.22816. Identity is specified at plus or minus 5 ppm reported to four decimal places, not at plus or minus 10 ppm, and the near-neighbor arithmetic in the variant note below is what forces the tighter figure across this whole family: the Epitalon and Vesugen pair sit about 93 ppm apart, and a looser tolerance cannot discriminate within the family.

Salt / variant note

The confusables field inverts on this record. The risk is not that a named analogue is substituted for a known compound; it is that any member of the Khavinson series can be shipped under this trade name and no arithmetic on the certificate contradicts it, because the name is a trade name and not a structure. What a buyer can do is identify which series member actually arrived. Computed from formula, all in-house: Vilon (KE) C11H21N3O5, 275.31 / 275.14812; Vesilut (ED) C9H14N2O7, 262.22 / 262.08010; Chonluten (EDG) C11H17N3O8, 319.27 / 319.10156; Cartalax (AED) C12H19N3O8, 333.30 / 333.11721; Thymagen (EW) C16H19N3O5, 333.34 / 333.13247, and note that Cartalax and Thymagen differ by 0.05 Da on average mass and print identically at one decimal place; Ovagen (EDL) C15H25N3O8, 375.38 / 375.16416; Epitalon (AEDG) C14H22N4O9, 390.35 / 390.13868; Vesugen (KED) C15H26N4O8, 390.39 / 390.17506, Epitalon and Vesugen differing by 0.04 Da average and 0.036 Da monoisotopic, about 93 ppm, which nominal-mass data does not separate at all; Pinealon (EDR) C15H26N6O8, 418.41 / 418.18121; Cortagen (AEDP) C17H26N4O9, 430.41 / 430.16998; Bronchogen (AEDL) C18H30N4O9, 446.46 / 446.20128; TESTAGEN (KEDG) C17H29N5O9, 447.45 / 447.19653, the critical neighbor for this record, exactly 14.03 Da lighter, one methylene, a single Gly-for-Ala substitution at the C-terminus and the likeliest single-residue error in the family; Prostamax (KEDP) C20H33N5O9, 487.51 / 487.22783; Cardiogen (AEDR) C18H31N7O9, 489.49 / 489.21833; Pancragen (KEDW) C26H36N6O9, 576.61 / 576.25438. Then the isomer class no mass measurement reaches: the compositional permutations of KEDA, among them KEAD, KDEA, KDAE, KAED, KADE, EKDA and DKEA, all share C18H31N5O9 and are identical at every decimal place of both average and monoisotopic mass; only the b/y ion series separates them. And the sideways risk out of the peptide line entirely: the Cytomax organ preparations are sold by the same vendors under the same brand lineage, are tissue extracts, and have no molecular mass to check.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

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

Published literature exists and the class is graded D: animal and in-vitro evidence only. What exists, by study type and identifier, and it is class-level rather than compound-specific. Khavinson VKh, Neuro Endocrinol Lett, 2002, PMID 12374906: review, animal and human studies, from the originating institution, describing the tissue-extract-to-synthetic-peptide program. Khavinson V, Linkova N, Diatlova A, Trofimova S, Stem Cell Reviews and Reports, 2020, PMID 31808038, DOI 10.1007/s12015-019-09938-8: review, and the publication carrying the program's own verbatim mechanistic claim. Khavinson VK, Kvetnoii IM, Bulletin of Experimental Biology and Medicine, 2000, PMID 11276315: animal study in rats. Khavinson VKh, Kuznik BI, Ryzhak GA, Advances in Gerontology, 2012, PMID 23734519: review of experimental and animal studies, Russian with English abstract. Khavinson VKh, Kuznik BI, Ryzhak GA, Advances in Gerontology, 2013, PMID 24003726: review of human clinical studies, Russian with English abstract, a review by the originating group and not a primary randomized trial, and it is the principal source relied on for every human-facing claim made about this family. Mironova ES et al., Advances in Gerontology, 2020, PMID 32593244: review. No compound-specific primary literature for this tetrapeptide was identified, and no independently replicated randomized human trial was located for the class. The class rests on animal and in-vitro work plus non-independent, largely Russian-language clinical reviews from the originating institution, and the volume of that literature does not establish what its volume suggests.

4 Storage & specification

Storage

White lyophilized powder, acetate salt, in a screw-cap amber borosilicate vial with a PTFE-lined closure; a laboratory-chemical presentation, non-sterile, with no sterility claim. Store at -20 degrees C plus or minus 5 degrees C, tightly closed and desiccated, protected from light. Moisture is the operative control and the reason is specific: the aspartyl succinimide route that governs this sequence is hydrolytic, so a desiccant sachet travels in the secondary pack, vials are equilibrated to ambient temperature before opening, and Karl Fischer water is measured at release and at every retest point rather than at release alone. Two acidic side chains and two basic sites make the salt hygroscopic; the container is closed immediately after weighing. Short peptides with free N- and C-termini are rapidly degraded by aminopeptidases and carboxypeptidases in any biological matrix, which is a substantive experimental consideration for the buyer's own work and is stated on the certificate rather than left to be discovered. Reconstituted solution is prepared fresh, aliquoted single-use and held at -80 degrees C.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C, desiccated, assigned by protocol and not measured, pending the company's own long-term and accelerated data on the first three commercial lots. The indicating attribute is the aspartyl succinimide and its iso-Asp ring-opened product, not gross purity and not intact mass: an all-L tetrapeptide with no cysteine, no methionine, no tryptophan and no tyrosine has nothing else moving, and the accelerated arm exists principally to force that one bond. Timepoints 0, 3, 6, 9, 12, 18 and 24 months at the labeled condition, plus 6 months at 40 degrees C / 75 percent relative humidity, with water content, counterion and the two named degradants reported individually at every pull. The label is shortened on data and never extended without a completed 24-month dataset from three lots.