Tripeptide-10 citrulline

Decorin is a protein-sugar molecule in the dermis that binds collagen fibrils and limits how they clump together, keeping fibers evenly sized and arranged. The developers reasoned that functional decorin declines as skin ages. They identified the two short sequences decorin uses to grip collagen, engineered variants with stronger binding, and screened them in a laboratory collagen fibril-formation assay; tripeptide-10 citrulline performed best.

In those experiments it shaped fibril assembly the way decorin does, producing thinner, more uniform collagen fibers. The stated aim is to influence the quality and organization of collagen rather than its amount. Whether enough of the peptide crosses intact skin to do this in people has not been shown in published studies.

Little has been published on it. The developer's 2008 paper reported laboratory work only: in a collagen fibril-formation assay, the peptide made collagen fibers thinner and more uniform, much like decorin¹. The one human study found is a small randomized trial in 24 healthy volunteers who applied products containing tripeptide-10 citrulline, acetyl hexapeptide-3, both, or neither for 60 days. Instrument measures of skin-surface roughness and water loss differed between some groups, and the authors described anti-wrinkle effects, but with about six people per group and many comparisons the results are preliminary². No larger or independent trials, and no studies of long-term outcomes, were found.

Not approved as a drug by the FDA or other regulators; it is used as a cosmetic ingredient under its INCI name¹.

Human data are minimal: one 24-person volunteer study, whose abstract does not report adverse effects². The developer's work was done in the laboratory, not in people¹. No published studies address irritation, allergy or long-term use.

1. Puig et al., Int J Cosmet Sci 2008PubMed
2. Raikou et al., J Cosmet Dermatol 2017PubMed