Matrixyl Synthe'6 (Palmitoyl Tripeptide-38): Evidence & Status

Palmitoyl tripeptide-38 — trade name Matrixyl Synthe'6, made by Sederma/Croda — is a synthetic, lipid-anchored matrikine peptide designed as a topical anti-aging cosmetic active. Its appeal in skincare is the claim that it tells dermal and epidermal cells to rebuild six extracellular-matrix constituents. This monograph separates that plausible mechanism from what has actually been demonstrated in human skin.1

This article is informational and editorial content for educational purposes only. It is not medical advice, not a protocol to follow, and not a sourcing or buying guide. Palmitoyl tripeptide-38 is a topical cosmetic ingredient, not an injectable or systemic drug. Dosing and concentration figures are reported strictly as seen in the published literature and manufacturer technical data, for completeness — not as recommendations. Consult a licensed clinician before using any new product.

What is Matrixyl Synthe'6 and how does it work?

Palmitoyl tripeptide-38 is the active in Matrixyl Synthe'6, a third-generation member of Sederma's Matrixyl family launched around 2011-2012.12 The molecule is a tripeptide — lysine-methionine-sulfone-lysine (Pal-Lys-Met(O2)-Lys) — bearing an N-terminal C16 palmitic-acid chain; molecular formula C33H65N5O7S, molar mass 675.97 g/mol, CAS 1101448-24-1.1 The peptide core is derived from a KMK sequence found in the connective-tissue proteins collagen VI and laminin. The methionine is oxidized to the sulfone form, reported to improve stability and receptor affinity, and the palmitoyl tail raises lipophilicity (logP about 4) to aid penetration of the skin's lipid barrier.11 The standard raw material (INCI: glycerin, water, hydroxypropyl cyclodextrin, palmitoyl tripeptide-38) contains 0.025 wt% active, the cyclodextrin acting as a solubilizing carrier.10

Mechanistically, matrikines are peptide fragments released from matrix proteins during tissue remodeling that act as signaling molecules to fibroblasts and keratinocytes.2 Palmitoyl tripeptide-38 is classed among signal peptides — one of four cosmetic-peptide groups (signal, carrier, neurotransmitter-inhibitory, enzyme-inhibitor) — that up-regulate matrix synthesis rather than relaxing muscle like neurotransmitter peptides. It is reported to act on two skin layers: in the epidermis, stimulating laminins, fibronectin, hyaluronic acid and CD44; and in the dermis, stimulating collagens I, III and IV, fibronectin and hyaluronic acid — hence the 'Synthe'6' name for six matrix constituents.29 Crucially, a precise membrane receptor has not been definitively characterized in peer-reviewed literature, so 'binds fibroblast receptors' is mechanistic inference and is graded down accordingly. As a leave-on topical, systemic pharmacokinetics are not the relevant frame; the CIR found no meaningful human absorption-distribution-metabolism-excretion data beyond percutaneous absorption for palmitoyl oligopeptides.7

What is the evidence by indication?

The single evidenced use is topical wrinkle reduction and dermal redensification. The supporting data fall into three tiers, summarized below.

The in-vitro findings establish biological plausibility, not clinical effect.29 The strongest human numbers come from a manufacturer placebo-controlled study reported in review literature: 25 women aged 42-70 applied 2% palmitoyl tripeptide-38 twice daily for two months, with forehead wrinkle volume and depth down 31% and 16.3% and a 28% improvement in 'lifting'; crow's-feet wrinkle surface, volume and maximum depth fell 28.5%, 21.1% and 15%.2 Those figures originate from Sederma's own technical dossier and have not been independently replicated.

The one peer-reviewed in-vivo study is Lintner, Gerstein & Solish (2020): a serum combining 15% L-ascorbic acid, vitamin E and 5 ppm palmitoyl tripeptide-38 in 35 women (mean age 64), applied once daily for 56 days, improved periorbital wrinkle metrics and skin-tone parameters.3 The caveats are decisive: open-label, no vehicle control, a multi-ingredient serum (the effect is not attributable to the peptide alone), funded by the manufacturer, and all three authors paid consultants — limitations the authors acknowledged. A separate three-study industry report reaches similarly favorable conclusions.4 Independent corroboration is absent: the 2026 systematic review and meta-analysis of peptides for skin aging — 19 RCTs, 1,341 participants, indexed at PubMed — included no RCT of palmitoyl tripeptide-38 at all, and judged the topical-peptide evidence base limited and heterogeneous.5

What doses and concentrations appear in the literature?

Reported strictly as information, not a protocol. The route is topical, leave-on facial application — no injectable, oral or systemic use is described in legitimate literature.2 Finished-product studies used the Matrixyl Synthe'6 raw material at about 2% (the raw material being 0.025 wt% active), and the peer-reviewed serum used 5 ppm of palmitoyl tripeptide-38.3 For palmitoyl peptides broadly, active concentrations of roughly 1-30 ppm are typical, with under 10 ppm customary.7 Frequency is once to twice daily, with visible or instrumented effects emerging at about 2-8 weeks of continuous use.3 There is no reconstitution step: this is a pre-formulated cosmetic active in a glycerin/water/cyclodextrin carrier, applied as supplied in finished products — it is not a lyophilized injectable peptide and should not be treated as one.10

How safe is palmitoyl tripeptide-38?

Across the in-vivo studies the peptide-containing serums were well tolerated, with no adverse effects attributed to the serum over 56 days.3 Palmitoyl peptides are generally regarded as non-irritating at cosmetic-use concentrations; a trade formulation at 100 ppm was non-irritating in a rabbit-eye test.7 Rare individual allergic or contact-sensitivity reactions are possible, so a patch test is advised.13 The honest data gap: the CIR noted that dedicated skin-irritation and sensitization studies, and absorption data beyond percutaneous absorption, were not found in the published literature — so safety rests largely on cosmetic-use history and the class's low systemic exposure rather than robust toxicology of this specific molecule.7 Unlike growth-factor actives, no credible angiogenesis or tumor-promotion signal has been reported for this matrikine; that risk is theoretical and not substantiated, but also not formally excluded by long-term human data. Avoid the eyelid margin and eyes, use caution on broken or inflamed skin, and in pregnancy or lactation seek clinician guidance, since peptide-specific safety data do not exist.11

What is the FDA and WADA status in 2026?

Palmitoyl tripeptide-38 is regulated as a cosmetic ingredient, not a drug. It has no FDA-approved therapeutic indication, requires no premarket approval as used cosmetically, and is INCI-listed and marketed in the US and EU.8 It is not a compounding bulk substance, not a 503A or 503B compounded drug, not DEA-scheduled, and not sold as an injectable 'research chemical, not for human use' — distinguishing it sharply from systemic injectable research peptides. As a cosmetic, marketing it with drug-like claims (altering skin structure or function to treat disease) would re-classify it as an unapproved drug under FDA law.8 Its safety is covered within the Cosmetic Ingredient Review assessment of palmitoyl oligopeptides.7

For athletes the picture is simple: not prohibited. Topical cosmetic peptides of this class do not appear on the WADA Prohibited List and impose no athlete restrictions.12 All reported in-vivo efficacy data are in women, with studied populations middle-aged to older (42-74) and established photoaging; effects in men, in younger skin and in darker skin types are unstudied.3

Bottom line. Matrixyl Synthe'6 pairs a coherent, well-described matrikine mechanism (Grade C, in-vitro) with real but low-tier human evidence for modest wrinkle softening (Grade B, lower bound). The strongest percentages are manufacturer-generated and the one peer-reviewed in-vivo study is open-label, vehicle-uncontrolled and confounded by co-ingredients. No independent RCT of this specific peptide exists. Legally it is low-risk: a cosmetic ingredient, not an approved drug, not WADA-banned, and not part of the injectable research-peptide gray market. Cross-reference the companion monographs on Matrixyl (palmitoyl pentapeptide-4) and Matrixyl 3000, the predecessor peptides.