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J Cosmet Dermatol. 2011 Sep;10(3):217-23. doi: 10.1111/j.1473-2165.2011.00569.x.

Facial skin-lightening benefits of the tetrapeptide Pro-Lys-Glu-Lys on subjects with skin types V-VI living in South Africa.

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Evonik Goldschmidt GmbH, Essen, Germany.



Irregular skin pigmentation may be a substantial contributor to the signs of aging and to a person's lack of psychological well-being. Although a large number of skin-lightening agents are available, the opportunity exists to identify more efficacious agents, agents that target alternative biological mechanisms.


To provide clinical evidence of the skin-lightening effect of the tetrapeptide, Pro-Lys-Glu-Lys (PKEK), on subjects with skin types V-VI living in South Africa.


Pro-Lys-Glu-Lys was evaluated in a double-blind and vehicle-controlled clinical study using expert grading of digital images by comparing its effects in subjects with skin types V-VI suffering from facial melasma and postinflammatory hyperpigmentation.


This study demonstrated the efficacy of PKEK on subjects with skin types V-VI. On comparing the two treatments, the skin-lightening peptide-containing formulation was significantly superior to the vehicle at 12 weeks on overall appearance (P < 0.05) and evenness of skin tone (P < 0.01).


The tetrapeptide, PKEK, has proven skin-lightening benefits on skin discoloration from melasma and postinflammatory hyperpigmentation. These studies have been conducted on subjects with skin types V-VI living in South Africa, but we believe this technology to be suitable for all racial groups.

[Indexed for MEDLINE]

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