Interesting research
Palmitoyl Pentapeptide-4
INCI: Palmitoyl Pentapeptide-4 · also pal-KTTKS, Matrixyl, matrikine peptide
A five amino acid fragment of type I collagen, with a palmitic acid tail bolted on so it can cross the stratum corneum. The idea is that the fragment reads to skin as evidence that collagen has been broken, and prompts it to make more.
Why it is here
A memo to skin, and skin reads it. In the best-known split-face trial, 93 women used 3 ppm of the peptide on one side of the face for 12 weeks and had fewer wrinkles and fine lines on that side, by instrument and by expert eye. One trial puts it in the interesting tier; the result puts it in the bottle.
When collagen degrades it releases short peptide fragments. Some of those fragments, called matrikines, act as signals in their own right. KTTKS is one of them, and in fibroblast culture it upregulates collagen I, collagen III and fibronectin. On its own it is far too water loving to get through skin, so the palmitoyl chain is added as a delivery strategy. It is a plausible memo. Whether skin reads it reliably is the open question.
The receipt
A moisturizer containing 3 ppm pal-KTTKS gave significant improvement versus the identical moisturizer without it for reduction in wrinkles and fine lines, by both quantitative image analysis and expert grading, over 12 weeks.
Topical palmitoyl pentapeptide provides improvement in photoaged human facial skin. International Journal of Cosmetic Science, 2005. split-face, n = 93 women aged 35 to 55. PMID 18492182
What the study actually did
- Study
- Robinson LR, Fitzgerald NC, Doughty DG, et al. Topical palmitoyl pentapeptide provides improvement in photoaged human facial skin. 2005.
- Journal
- International Journal of Cosmetic Science 27:155-160
- Design
- Double-blind, placebo-controlled, split-face, left-right randomised
- Subjects
- 93 women aged 35 to 55 with photoaged skin
- Concentration
- 3 ppm palmitoyl pentapeptide (pal-KTTKS) in a moisturizer
- Duration
- 12 weeks
- Outcome
- Significant reduction in wrinkles and fine lines versus placebo
In practice
- Typical use
- 3 ppm of the peptide is the studied level. Suppliers usually sell it as a dilute trade solution recommended at 3 to 8 percent of the formula, which lands in that single-digit ppm range.
- Pairs with
- Niacinamide, Copper Tripeptide-1, Retinal
- Keep apart from
- Very low pH actives in the same layer: peptides are more stable near neutral, and there is no benefit to putting this one in an acidic environment.
- Cautions
- None notable. It was well tolerated in the trial and is used at parts-per-million levels. The main thing to watch for is a formula that lists it but does not say at what level.
Questions people ask
Why is Matrixyl in the interesting tier if it has a real trial?
Because it has one good trial: 93 people, double-blind, placebo-controlled, split-face, with fewer wrinkles and fine lines on the peptide side after 12 weeks. One well-run trial is real evidence. A second one at the same standard, from a different lab, is what moves an ingredient into the good tier, and until then it sits in interesting with its result intact.
Three parts per million sounds like nothing. Is that a real dose?
It is the dose that produced the published result, and for a signalling molecule that is the relevant number rather than the intuitive one. Peptides act by binding, not by bulk. More is not automatically better, and a brand advertising a much higher peptide percentage is usually quoting the trade solution, not the peptide.
Can I use peptides with retinal?
Yes. They are working on different parts of the same problem and there is no known chemical conflict at cosmetic levels. In our routine they sit in different products at different times mostly for tolerance reasons: a peptide serum in the evening under a retinal cream is a common and sensible layering order.