SNAP-8 (Acetyl Octapeptide-3)

1 Identity

Synthetic N-acetylated, C-terminally amidated octapeptide; bulk cosmetic ingredient with a current INCI name. Structurally it is the acetyl hexapeptide-8 sequence extended by two C-terminal residues, Ala7 and Asp8, with the primary amide carried forward onto the aspartate. All eight residues proteinogenic and L-configured; no cysteine, no disulfide, no D-residue and no non-proteinogenic residue, stated explicitly so that P3 is not applied by reflex. Two glutamates and one aspartate against two arginines make the free base amphoteric, and it is supplied as a salt. CAS 868844-74-0. "SNAP-8" is a supplier trade designation derived from SNAP-25 and is not an official name of the substance; it is recorded here for identification only and does not appear on our label or metadata. acetyl glutamyl heptapeptide-1 and acetyl glutamyl heptapeptide-3 (alternative INCI designations encountered commercially on the same article). A precisionFDA GSRS substance record exists under the preferred term acetyl octapeptide-3. Do not treat acetyl octapeptide-3 and acetyl hexapeptide-8 or acetyl hexapeptide-3 as interchangeable: they are different molecules 186.17 Da apart, and the hexapeptide names belong to the separate Argireline record in this catalog.

Sequence

Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2; one-letter Ac-EEMQRRAD-NH2, eight residues. The N-acetyl sits on the Glu1 alpha-amino nitrogen and is part of the molecule, not a protecting group left in place; it is localized by MS/MS b1/b2 assignment rather than inferred from intact mass. The C-terminus is a primary carboxamide on Asp8, not the free acid, and that distinction is worth 0.98 Da. Met3 is the oxidation-labile residue. Asp8 sitting at an amidated C-terminus is a deamidation and succinimide or iso-aspartyl rearrangement site, which is the specific chemical reason this molecule needs a stability-indicating gradient rather than a generic one. The sequence as written is corroborated by two independent supplier monographs and by residue-by-residue reconstruction from the formula.

Molecular formula

C41H70N16O16S (free base). Normally supplied as the acetate or trifluoroacetate salt, with the counterion identified and quantified rather than assumed. A formula in wide circulation for this article, C40H68N14O15S, is arithmetically impossible against the molecular weight printed beside it: C40H68N14O15S computes to 1017.127 average, 58.04 Da away from the roughly 1075 Da that the same listings publish, and the two cannot both describe one substance. The correct formula, reconstructed residue by residue from the sequence above and corroborated by two independent supplier monographs, is C41H70N16O16S at 1075.167 average and 1074.48764 monoisotopic. The CAS number is corroborated by the same commercial sources and is carried for identification, not as identity.

Average mass

1075.167 Da (C41H70N16O16S) from the formula on IUPAC 2021 abridged conventional atomic weights (C 12.011, H 1.008, N 14.007, O 15.999, S 32.06). Suppliers publish 1075.2 for the same formula, which is the same number to the precision they state it.

Monoisotopic mass

1074.48764 Da neutral free base; [M+H]+ 1075.49492; [M+2H]2+ 538.25110; [M-H]- 1073.48037. At this mass a 5 ppm window on [M+H]+ is plus or minus 0.0054 Da, which separates the free acid (+0.98 Da) and the des-acetyl species (-42.04 Da) without difficulty but does not on its own exclude an iso-aspartyl rearrangement, which is exactly isobaric.

Salt / variant note

(1) the parent hexapeptide, which is the commercial substitution. Acetyl hexapeptide-8, Ac-EEMQRR-NH2, C34H60N14O12S, 889.000 avg / 888.42358 mono — 186.17 Da lighter, a two-residue shorter synthesis, and the cheaper article by the milligram in every catalog that stocks both. A certificate reporting 889 under a SNAP-8 label is the hexapeptide. (2) The free acid Ac-EEMQRRAD-OH, C41H69N15O17S, 1076.151 avg / 1075.47166 mono, 0.98 Da heavier and invisible to any instrument reporting "1075". (3) The des-acetyl octapeptide H-EEMQRRAD-NH2, C39H68N16O15S, 1033.130 avg / 1032.47708 mono, 42.04 Da lighter, the direct process residue when the capping step is incomplete. (4) Met3 sulfoxide, C41H70N16O17S, 1091.166 avg / 1090.48256 mono, +15.999; Met3 sulfone at +31.998. This is the governing degradation class and the reason the nitrogen blanket is a specification and not a habit. (5) the variant that carries no mass difference at all: succinimide-mediated iso-aspartyl and D-iso-aspartyl rearrangement at Asp8, exactly isobaric at 1075.167 / 1074.48764 and detectable only chromatographically; the succinimide intermediate itself is 18.02 Da light at 1057.15. (6) Salt state, which is where the money moves. As the mono-acetate the free base is 94.7 percent of the powder; as the mono-trifluoroacetate 90.4 percent; the molecule has two basic side chains, so multiple equivalents are possible and stoichiometry is measured, never assumed. (7) the trade-solution variant, a tenfold assay difference rather than a chemical one: cosmetic-ingredient houses ship aqueous or aqueous and glycerin solutions, so a drum label reading 10 percent SNAP-8 denotes the supplier's dilute trade solution, not 10 percent peptide content. (8) The naming variant: acetyl glutamyl heptapeptide-1 and acetyl glutamyl heptapeptide-3 are alternative INCI designations encountered on this same article, and a certificate using either is acceptable only if the sequence and the measured mass are on it.

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 primary literature on this molecule was not located, and that absence is the finding. PubMed returns nothing for octapeptide-3 as a cosmetic wrinkle peptide; broader terms combining acetyl octapeptide and SNAP-8 return only unrelated biochemistry (cholecystokinin octapeptide, angiotensin, prion octapeptide repeats, the Pax5 octapeptide domain, C3a anaphylatoxin). No Cosmetic Ingredient Review Expert Panel safety assessment of acetyl octapeptide-3 was located, although CIR assessments were located for acetyl hexapeptide-8 amide and for several other peptide ingredient groups. No registered or published human study of the single agent was located. The one general item that does apply is Imhof and Leuthard, Dermatology 2021, a systematic review of topical over-the-counter antiaging agents, PMID 32882685, which states the class-level position that evidence supporting such ingredients is often lacking. Adjacent literature that belongs to other molecules and is routinely borrowed for this one: Blanes-Mira 2002 (PMID 18498523), an in-vitro study of the hexapeptide, and Kraeling 2015 (PMID 24754410), a human-skin penetration study of the hexapeptide. Neither is a study of this article, and the citation index will not let one borrow the other's references. Comparative-efficacy figures for this ingredient circulate in trade literature with no located primary source behind them; they are not reproduced here. An absence in the literature is an absence of evidence and not a finding in either direction.

4 Storage & specification

Storage

The labeled condition is lyophilized white to off-white powder in amber Type I glass with a bromobutyl stopper, headspace displaced with nitrogen, one desiccant sachet per shipper, stored at -20 degrees C plus or minus 5 degrees C, desiccated, protected from light and moisture. The nitrogen blanket and light protection are the specific controls for Met3 oxidation, and the label states that reason so a receiving technician cannot treat them as optional. Two arginines make the salt hygroscopic: the written procedure requires the container to be equilibrated to room temperature inside the desiccator before opening, because condensation on a hygroscopic peptide is the commonest way a good lot is ruined after release. Headspace is re-blanketed after any subdivision. Reconstituted aqueous solutions are markedly less stable than the dry powder, are held at 2 to 8 degrees C and are treated as single-use; pH excursions accelerate the Asp8 rearrangement and are controlled rather than tolerated. Shipped on gel packs with a single-use electronic temperature logger in every shipper, excursion limits set by the shipping validation and not by the courier.

Shelf life

Provisional 24-month retest interval at -20 degrees C plus or minus 5 degrees C, desiccated and light-protected. Provisional is meant literally: the interval is carried only until this company's own stability program reports, with retains from every launch lot pulled at 0, 3, 6, 9, 12, 18 and 24 months at -20 degrees C, a parallel accelerated arm at 5 degrees C plus or minus 3 degrees C and at 25 degrees C and 60 percent relative humidity, all assayed by the stability-indicating RP-HPLC method validated to resolve iso-aspartyl from aspartyl. Two attributes are trended by name because they are the two known failure routes on this sequence: total oxidized species (Met sulfoxide plus sulfone) and total iso-aspartyl. The interval is shortened without notice if either exceeds 0.3 percent growth per year at the labeled condition, and that trigger is written into the protocol rather than left to judgment. The label carries a retest date, not an expiry date. Material reaching retest is re-assayed for purity, water 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 exist for this molecule; every statement here is this company's own protocol, not a literature finding.