The regulation of collagen fibres is controlled by a number of molecules one of which is called decorin. As we get older, decorin activity declines. The new peptide, tripeptide-10 citrulline, is supposed to mimic decorin so that the collagen fibres are fooled into thinking they should still be productive.
A trial was conducted on 43 women, about half of which were given tripeptide-10 citrulline. Granted this was conducted by the manufacturer, Lipotec. Nevertheless, the results (published in the International Journal of Cosmetic Science) aren't bad with 54% showing an increase in skin suppleness. Over a two month period, it was shown to make the fibres more uniform.
Look out for a tripeptide-10 citrulline showing up in potions and lotions later this year.