Syn-AKE

1 Identity

Synthetic tripeptide benzylamide, supplied as the diacetate salt; bulk cosmetic ingredient with a current INCI name. Note the naming trap on the face of the INCI term: the ingredient is called a dipeptide and the molecule is a tripeptide derivative — three residues joined by two peptide bonds, with a benzylamide cap in place of the C-terminal acid. The name has been repeated across the trade for two decades without the discrepancy being flagged, and a seller who has not noticed it has not read the structure. Two of the three residues are non-proteinogenic: beta-alanine, which is a beta- rather than an alpha-amino acid and therefore has no alpha-stereocenter, and 2,4-diaminobutyric acid (Dab). L-proline is the only proteinogenic residue. Two stereocenters, at Pro and at Dab; no cysteine, no disulfide, no metal. 4-diamino-N-(phenylmethyl)butanamide diacetate; CAS 823202-99-9; PubChem CID 71465152. a registered trade name recorded for identification only and appearing on no label or metadata of ours; dipeptide diaminobutyroyl benzylamide diacetate (current INCI name); H-beta-Ala-Pro-Dab-NH-Bzl - 2 AcOH; beta-alanyl-L-prolyl-2. Marketed on an analogy to waglerin-1.

Sequence

H-beta-Ala-L-Pro-L-Dab-NH-CH2-C6H5, written H-beta-Ala-Pro-Dab-NHBzl. Three residues. The N-terminus is a free primary amine on beta-alanine. Position 2 is L-proline. Position 3 is L-2,4-diaminobutyric acid, whose side chain carries a second primary amine. The C-terminus is a secondary amide to a benzyl group — not a free acid and not a primary carboxamide — and that benzylamide is the reason the molecule behaves on reversed phase like something far more lipophilic than a tripeptide of this size. No one-letter string exists for this molecule and none should be accepted on a certificate: beta-alanine and Dab have no one-letter codes, and a written "APX" or similar encodes nothing. Beta-alanine has no alpha-carbon substituent, so the only chiral centers to control are Pro and Dab.

Molecular formula

C19H29N5O3 (free base); C23H37N5O7 as the diacetate, which is the supplied article and the form the INCI name and the CAS number describe. The formula is reconstructed residue by residue rather than copied, and it is corroborated against two independent commercial and registry sources.

Average mass

495.577 Da for the diacetate C23H37N5O7 and 375.473 Da for the free base C19H29N5O3, both on IUPAC 2021 abridged conventional atomic weights. Suppliers publish 495.58 for the diacetate, which is the same number to the precision stated. The free base is 75.8 percent of the diacetate by mass, so a content claim that does not say which of the two it means is out by a third, and any document that quotes one figure without naming the form it belongs to is a red flag.

Monoisotopic mass

Diacetate 495.26930 Da; free base 375.22704 Da, [M+H]+ 376.23432, [M+2H]2+ 188.62080. In electrospray the acetate counterions dissociate, so the observed ion is the free base at 376.23, and a certificate reporting 496.3 as the measured [M+H]+ has not understood its own experiment.

Salt / variant note

(1) the salt state is the commercial article and it is where the money moves. Free base C19H29N5O3 375.473 / 375.22704; mono-acetate C21H33N5O5 435.525 / 435.24817; diacetate C23H37N5O7 495.577 / 495.26930, the declared form. The molecule has two basic centers (the beta-alanine alpha-amine and the Dab side-chain amine), so two acetate equivalents is chemically sensible and is still measured rather than assumed. Free base is 75.8 percent of the diacetate and 86.2 percent of the mono-acetate. (2) The des-benzyl free acid H-beta-Ala-Pro-Dab-OH, C12H22N4O4, 286.332 / 286.16411, 89.14 Da below the benzylamide — simultaneously the hydrolysis degradant and the incomplete-synthesis residue, and far more polar, so a gradient tuned for the parent may not retain it at all. (3) The des-benzyl primary amide C12H23N5O3 285.348 / 285.18009. (4) The truncated dipeptide Pro-Dab-NHBzl C16H24N4O2 304.394 / 304.18993, 71.08 Da light, which is what a failed first coupling delivers — and which is, ironically, an actual dipeptide sold under an INCI name that says dipeptide. (5) The Dab-to-ornithine homolog C20H31N5O3 389.500 / 389.24269, one CH2 heavy at 14.03 Da, and the Dab-to-diaminopropionic-acid lower homolog C18H27N5O3 361.446 / 361.21139, one CH2 light — both from the wrong protected building block and both invisible to a nominal-mass instrument reporting "375". (6) the variant no mass can catch: substituting L-alanine for beta-alanine gives an exact constitutional isomer at C19H29N5O3, 375.473 / 375.22704, and the D-Pro and D-Dab diastereomers are likewise exactly isobaric. That is why P3 and a chiral method, and not P1: with two of three residues non-proteinogenic, two stereocenters and an exact isobar available by a single substitution, a chiral method is mandatory rather than advisory, and a panel assigned by reflex would produce a certificate that cannot establish identity. (7) The trade-solution variant: cosmetic houses ship this ingredient as a dilute aqueous solution, typically at 1 to 4 percent in finished formulations, so a percentage on a drum label denotes solution strength and not peptide content.

2 Class & testing panel

Form

Single article

Testing panel

P3 — panel definition

3 Primary sources & evidence

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

Compound-specific primary literature was not located, and that absence is the finding. No in vitro, animal or human study of this ingredient under its own name was identified across cosmeceutical peptide reviews, Cosmetic Ingredient Review safety assessments and INCI-name searching; no CIR Expert Panel safety assessment of dipeptide diaminobutyroyl benzylamide diacetate was identified, though CIR assessments of other peptide ingredients were. No human trial of any individual member of that ingredient group was identified and no NCT numbers are quoted, because none were found. The general item that applies at class level is Imhof and Leuthard, Dermatology 2021, PMID 32882685, a systematic review of topical over-the-counter antiaging agents. The delivery literature that is routinely cited for this ingredient belongs to other molecules and the citation index will not let it be borrowed: Kraeling 2015 (PMID 24754410) is a human-skin penetration study of acetyl hexapeptide-8, and Choi 2014 (PMID 25143811) concerns a palmitoylated collagen pentapeptide. Waglerin-1, the venom peptide the trade name alludes to, has its own literature, which is not literature about this article; the waglerin-1 analogy and the nicotinic-receptor rationale that accompany it in the trade are marketing devices, and no primary study of this molecule was located behind either. The gap points to a straightforward experiment: no published nicotinic acetylcholine receptor binding assay of this specific molecule was identified.

4 Storage & specification

Storage

Lyophilized or crystalline white to off-white powder as the diacetate, in the sealed original container, amber glass or an opaque HDPE bottle with an induction seal, one desiccant sachet per shipper. Labeled storage -20 degrees C plus or minus 5 degrees C, desiccated, protected from light and moisture; the container is equilibrated to room temperature inside the desiccator before opening, because a diacetate salt of a small basic peptide is hygroscopic and condensation is the commonest way a good lot is ruined after release. The benzylamide is the hydrolysis-sensitive bond and the two free amines make the article pH-sensitive in solution, so reconstituted material is held at 2 to 8 degrees C, buffered rather than left in water, and treated as single-use; freeze-thaw cycling is recorded rather than assumed harmless. Shipped on gel packs with a single-use electronic temperature logger in every shipper; excursion limits are set by the shipping validation, not by the courier. Incompatible with strong oxidizing agents; no metal-chelation or copper-compatibility question arises on this article, unlike the copper-bearing members of the cosmetic group it is usually cataloged beside.

Shelf life

Provisional retest interval 24 months at -20 degrees C plus or minus 5 degrees C in the sealed original container, desiccated and light-protected, stated as provisional pending this company's own stability data. The confirming study is long-term at -20 degrees C with pulls at 0, 3, 6, 9, 12, 18 and 24 months, accelerated at 5 degrees C plus or minus 3 degrees C and at 25 degrees C with 60 percent relative humidity, assayed by the stability-indicating RP-HPLC gradient with the des-benzyl acid at 286.33 trended by name as the governing degradant, because benzylamide hydrolysis is the only obvious chemical failure route on this structure. Water content is trended alongside it, because the acetate salt is hygroscopic and water uptake is the practical driver of that hydrolysis. The label carries a retest date, not an expiry date, and the interval is shortened without notice if a pull fails. Material reaching retest is re-assayed for purity, water, counterion stoichiometry and net peptide content and is either re-dated for a further 12 months or destroyed and recorded on the public failed-lot ledger. No compound-specific published stability data were located for this molecule; every statement here is this company's protocol, not a literature finding.