Collagen-fragment peptide · wrinkles
A cosmetic ingredient that joins palmitic acid to lysine-threonine-threonine-lysine-serine (KTTKS), a five-amino-acid piece of type I procollagen, the precursor of the skin's main structural protein. In mouse-skin experiments the fatty tail made the peptide more stable and better able to enter skin than the bare fragment. It is best known by the trade name Matrixyl.
When collagen is made, the ends of its precursor are cut off, and some of those pieces appear to signal back to the cells that made them. In 1993, researchers traced this activity to KTTKS, the smallest piece that still strongly stimulated collagen and fibronectin production in cultured fibroblasts and other connective-tissue cells1. Pal-KTTKS was designed to deliver that signal from the skin surface.
In hairless-mouse skin, both forms broke down quickly, the palmitoylated one less so; the bare peptide was not found in any skin layer, while the palmitoylated form reached the stratum corneum, epidermis, and dermis, though neither crossed full-thickness skin2.
There is a modest amount of controlled human data. In a 12-week double-blind, split-face trial run by Procter & Gamble in 93 women aged 35 to 55, a moisturizer with Pal-KTTKS was compared with the same moisturizer without it; the peptide side showed significantly greater reduction in wrinkles and fine lines by image analysis and expert grading3.
A 2023 randomized trial in 21 Indonesian women compared eye-area creams containing palmitoyl pentapeptide-4, acetyl hexapeptide-3, or placebo for eight weeks; the authors judged the pentapeptide cream best, but with about seven women per group they called it an initial study needing larger follow-up4. Beyond these, much of the support is cell and skin-permeation work1,2.
Not approved as a drug by the FDA or any other regulator found; it is used as a cosmetic ingredient2. In the US, cosmetic ingredients do not need FDA approval before they go on the market, while a product intended to affect the structure or function of the body is regulated as a drug5.
In the 93-woman split-face trial, the peptide moisturizer was well tolerated3. Beyond that, published human data on side effects are sparse, and there are no long-term studies. As with any topical cosmetic, the finished product can irritate skin or cause contact allergy.
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