Vialox (Pentapeptide-3V)

1 Identity

Base synthetic pentapeptide, C-terminally amidated. Five residues, four of them proteinogenic L-amino acids and one achiral (glycine), free N-terminal alpha-amino group, no acylation, no cyclization, no cysteine, no disulfide, no metal, no non-proteinogenic residue. The single modification is the C-terminal primary amide at Ala5 in place of a free acid, and it is an identity attribute rather than a detail. One strongly basic center, the arginine guanidinium, plus the N-terminal amine; no aromatic residue, therefore no 280 nm chromophore. Two proline residues in a five-residue chain make cis/trans amide-bond isomerism a real chromatographic phenomenon rather than a theoretical one. Sold as a bulk topical cosmetic ingredient and laboratory raw material, in neat powder form by research vendors and as a formulated aqueous solution under the trade name by the ingredient house. and the correct designation is pentapeptide-3. no CAS number and no registry entry: the trailing V is a contraction of the trade name. with the salt form indexed separately as Vialox peptide diacetate. "Pentapeptide-3V" has no INCI listing. recorded for identification only and appearing on no label or metadata of ours; H-Gly-Pro-Arg-Pro-Ala-NH2; GPRPA-NH2; glycyl-L-prolyl-L-arginyl-L-prolyl-L-alaninamide; CAS 135679-88-8; PubChem CID 11605666. which is the current INCI name and the correct chemical designation; Vialox.

Sequence

H-Gly-L-Pro-L-Arg-L-Pro-L-Ala-NH2 (GPRPA-NH2). Five residues; Gly1 is achiral, Pro2, Arg3, Pro4 and Ala5 are L. Free N-terminal alpha-amino group; C-terminal primary amide, not a free acid. No acetylation, no acylation, no cyclization, no disulfide, no non-proteinogenic residue. The amide is the attribute a resin choice gets wrong and a mass method must therefore prove: the free acid is a different article 0.984 Da heavier. Two prolines in five residues have a practical consequence that belongs on the specification and not in a footnote — slow cis/trans isomerization about the Xaa-Pro bonds produces broadened or split peaks on a fast reversed-phase gradient at ambient temperature, which is a conformational artifact and not an impurity, and a method that does not control column temperature will report it as one.

Molecular formula

C21H37N9O5 as the free peptide — the form the CAS number and the INCI name describe. Salt forms carried as separate formula units and not folded into the identity: mono-acetate C23H41N9O7; diacetate C25H45N9O9, which is separately indexed at PubChem CID 127258903; mono-trifluoroacetate C23H38F3N9O7; di-trifluoroacetate C25H39F6N9O9. With two basic centers the article readily carries two counterions, so the salt state is a stated attribute rather than an assumption.

Average mass

Average mass 495.585 Da (C21H37N9O5), computed from the formula and independently reconstructed residue-by-residue from Gly-Pro-Arg-Pro-Ala with a C-terminal amide; the two routes return the same formula and the same number, and a supplier listing publishes MW 495.58 for the same formula, which is the same figure to the precision stated. Salt forms: mono-acetate 555.637; diacetate 615.689; mono-trifluoroacetate 609.607; di-trifluoroacetate 723.629. The free peptide is 80.5 percent of the diacetate and 68.5 percent of the di-trifluoroacetate by mass, so a content claim that does not say which it means is out by up to 31 percent.

Monoisotopic mass

495.29177 Da neutral (C21H37N9O5). Working ions: [M+H]+ m/z 496.29905, [M+2H]2+ m/z 248.65316. A plus or minus 5 ppm window on the neutral is plus or minus 0.0025 Da. Free acid (des-amido) C21H36N8O6, 496.569 average / 496.27578 monoisotopic — plus 0.98401 Da, and at the 2+ charge state that gap is 0.49 m/z. Diacetate formula unit 615.33402; mono-acetate 555.31289. Two basic centers and a guanidinium make 2+ the dominant ion in positive-mode electrospray, so the charge state is printed on the certificate and the des-amido limit is demonstrated at the charge state actually used.

Salt / variant note

A mass collision between two articles sold from the same catalog page at the same size. Syn-AKE, dipeptide diaminobutyroyl benzylamide diacetate, is supplied as the diacetate and that is the form its INCI name and CAS number describe: C23H37N5O7, 495.577 average / 495.26930 monoisotopic. This article as the free peptide is C21H37N9O5, 495.585 average / 495.29177 monoisotopic. The average masses differ by 0.008 Da. A certificate printing "MW 495.6", or any nominal or single-quadrupole figure, cannot distinguish them, and both articles are sold in the same 200 mg size. The monoisotopic masses differ by 0.02247 Da, which is 45 ppm at m/z 495 — resolvable at the plus or minus 5 ppm this panel requires and invisible at anything coarser. Two cheap discriminators exist and both are written into the certificate: elemental composition, since N9O5 against N5O7 is unmistakable in an accurate-mass fit, and the isotope pattern that follows from it. Other variants. (1) free acid (des-amido) C21H36N8O6, 496.569 / 496.27578, plus 0.984 Da: the characteristic defect of an amide-terminating synthesis, partially co-eluting, a different article. (2) salt axis: free peptide 495.585, mono-acetate 555.637, diacetate 615.689 (separately indexed at PubChem), mono-trifluoroacetate 609.607, di-trifluoroacetate 723.629; the free peptide is 68.5 percent of the di-trifluoroacetate. (3) sequence-adjacent articles, each computed from its formula: GPRP-NH2 C18H32N8O4, 424.506 / 424.25465, this sequence minus its C-terminal Ala and 71.08 Da lighter, the truncation a failed first coupling leaves behind; GPRP free acid C18H31N7O5, 425.490 / 425.23867, a stocked reagent in the fibrin literature under its own name; GPRPG-NH2 C20H35N9O5, 481.558 / 481.27612, Ala-for-Gly and 14.03 Da lighter; APRPA-NH2 C22H39N9O5, 509.612 / 509.30742, Gly-for-Ala and 14.03 Da heavier; GPKPA-NH2 C21H37N7O5, 467.571 / 467.28562, Lys-for-Arg and 28.01 Da lighter. (4) STEREOISOMERS: four chiral centers, all isobaric with the parent at every resolution; the all-D and mixed-configuration peptides are invisible to mass. (5) CONFORMERS, not impurities: cis/trans isomerism about the two Xaa-Pro bonds broadens or splits peaks on an uncontrolled gradient. (6) same-shelf cosmetic articles at the same 200 mg size: Pentapeptide-18 (Leuphasyl), Syn-Coll, palmitoyl tetrapeptide-7, AHK-Cu, Pal-GHK, Pal-AHK, Nonapeptide-1, Decapeptide-12 and "Lipopeptide" — the last of which is a structural class rather than a molecule.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definitionP1 rather than P2 or P3, and the reason is on the face of the structure: there is no D-residue and no non-proteinogenic residue, so P3 would be wrong, and there is no acylation, so P2 would be wrong. Chirality is nonetheless a first-lot qualification test, because the four stereocenters are isobaric with the parent. Column temperature is controlled on the purity method so that a cis/trans proline conformer is not integrated as an impurity, and the elemental-composition fit from accurate mass is a printed release attribute rather than a good-practice extra

3 Primary sources & evidence

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

Literature exists for the field, and no compound-specific primary literature was located for this article under its own INCI name — in vitro, animal or human — in a search covering cosmeceutical peptide reviews, Cosmetic Ingredient Review safety assessments and targeted INCI-name searches, nor in a further search of 14 August 2026. The eleven-ingredient cosmetic group carries an evidence grade of F on that basis: no meaningful primary evidence, mechanisms asserted by analogy to better-characterized molecules, and product claims tracing to supplier technical literature rather than to independent peer-reviewed work. Claims circulating in the trade under this name are not restated here, in either direction, because restating a claim in order to rebut it still puts it on the page. Class-level citations, kept separate on the catalog page and belonging to other molecules: Kraeling et al., Cutan Ocul Toxicol 2015, PMID 24754410, in vitro, excised human cadaver and hairless guinea pig skin; Choi et al., Biomol Ther 2014, PMID 25143811, in vitro, hairless mouse skin; Imhof and Leuthard, Dermatology 2021, PMID 32882685, systematic review; Chen et al., World J Clin Cases 2021, PMID 33748252, case report on injection of a cosmetic peptide. No human trial of this article was located and no NCT number is quoted because none was found; ClinicalTrials.gov could not be queried within that search, so this is "none located" rather than "none exist". No Cosmetic Ingredient Review safety assessment for this specific ingredient was located in a targeted search that did return assessments for other peptide ingredients. Literature volume by study type is printed at the head of the research page.

4 Storage & specification

Storage

White to off-white lyophilized powder in the sealed original jar with in-pack desiccant, protected from light and moisture; non-sterile, no sterility claim, no stoppered-and-crimped format, no dose-shaped vial. Labeled storage 2-8 degrees C for the working jar and -20 degrees C plus or minus 5 degrees C for the retained reference portion, both desiccated. The article is freely water-soluble and needs no co-solvent, which distinguishes it from the palmitoylated members of the same shelf and is a handling fact and nothing more. It is hygroscopic, and the jar is equilibrated to room temperature sealed before opening so that condensation does not move the water figure and with it the net peptide claim. Shipped ambient with a temperature-excursion indicator; cumulative excursions to 25 degrees C for up to 14 days are accepted against the stability protocol and recorded on the lot record. Reconstituted aqueous solutions are refrigerated and used promptly — free-termini peptides with an unblocked N-terminus are substrate for any residual aminopeptidase activity in a biological matrix.

Shelf life

Provisional 24-month retest interval at 2-8 degrees C, and provisional 36 months at -20 degrees C plus or minus 5 degrees C for the retained reference portion, both provisional placeholders for this company's own ICH Q1A-format study on three production lots — long-term at 5 degrees C plus or minus 3 degrees C, accelerated at 25 degrees C / 60 percent RH — replacing them at the 12-month data point. The stability-indicating attribute is C-terminal amide hydrolysis to the free acid at plus 0.984 Da, and the method must be demonstrated to resolve it from parent before the first lot goes on stability; an area-percent purity figure alone does not date this molecule, because the degradant partially co-elutes with it. Water content is trended alongside. There is no oxidation-labile residue — no Met, no Trp, no Cys — and no aspartyl-glycine motif, so photostability is not the governing arm here as it is on the tyrosine-containing articles on the same shelf. Shortened on data, never extended without a completed dataset.