Therapeutic Peptides in Aged Skin

By: Farzam Gorouhi, MD, and Howard I. Maibach, MD, University of California School of Medicine

Posted: August 28, 2009, from the September 2009 issue of Cosmetics & Toiletries.

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Pal-KTTKS: Palmitoyl pentapeptide-4 (Pal-KTTKS) is a synthetic signal peptide from pro-collagen I fragments. It stimulates collagen I, III and VI, in addition to fibronectin, elastin and glycosaminoglycan production.¹³ These effects have made it a popular ingredient in antiaging and antiwrinkle products.

In a study¹⁴ of 93 Caucasian females, Pal-KTTKS performed significantly better than a placebo, as assessed by expert graders and subjective observations, for the treatment of hyperpigmented age spots. Osborne et al. also showed a robust result for this peptide in reducing bumpy texture and fine wrinkles.¹⁵

Kinetin: Kinetin is another signal peptide that is derived naturally from plants. It exhibits antioxidant properties, delaying the onset of aging characteristics in human fibroblasts, and inhibits keratinocyte growth.16 Its cosmeceutical indication is mainly limited to antiaging, antiwrinkle and anti-solar purposes.

In a randomized, double-blind study, Chiu et al. compared topical kinetin with niacinamide to niacinamide alone and found significant reductions in spot, pore, wrinkle and erythema index and evenness counts in the kinetin with niacinamide group. Furthermore, significant increases in corneal hydration status were found in the same group.¹⁷ Several growth factors and cytokines have been applied to treat skin problems in elderly individuals.

Human growth factor: An antioxidant serum containing liposome-encapsulated transforming growth factor beta (TGF-β1), ascorbic acid and Cimicifuga racemosa extract in a silicone base was developeda, applied to the arms of test subjects, and compared with a placebo serum omitting the TGF-β1.¹⁸ The skin of subjects treated with TGF-β1 revealed a significant mean improvement (21.7%) in physician-rated wrinkle scores while the placebo-treated skin recorded a slight improvement (6.2%) over the baseline.