The First Human Clinical Trial on the Skin Depigmentation Efficacy of Glycinamide Hydrochloride

Yong Chool Boo; Da Jung Jo; Chang Min Oh; Shin Young Lee; Young Mi Kim

doi:10.3390/biomedicines8080257

The First Human Clinical Trial on the Skin Depigmentation Efficacy of Glycinamide Hydrochloride

Biomedicines. 2020 Jul 31;8(8):257. doi: 10.3390/biomedicines8080257.

Authors

Yong Chool Boo^{1

2

3

4}, Da Jung Jo⁵, Chang Min Oh^{1

2

3}, Shin Young Lee⁴, Young Mi Kim⁴

Affiliations

¹ Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 41944, Korea.
² Brain Korea (BK) 21 Plus Kyungpook National University (KNU) Biomedical Convergence Program, Kyungpook National University, Daegu 41944, Korea.
³ Cell and Matrix Research Institute, Kyungpook National University, Daegu 41944, Korea.
⁴ Ruby Crown Co., Ltd., Suite 505, Korea Mediventure Center, 76 Dongnae-ro, Dong-gu, Daegu 41061, Korea.
⁵ Dermapro Skin Research Center, Dermapro Ltd., Seoul 06684, Korea.

Abstract

A previous study identified certain low molecular anti-melanogenic peptides that share a common sequence with α-melanocyte stimulating hormone (MSH) and end with a glycinamide moiety. Glycinamide itself also showed anti-melanogenic activity in cell-based assays, but neither glycine nor acetyl glycinamide were active, which indicated a special structure and activity relationship. The aim of this study was to examine the skin depigmentation efficacy of glycinamide hydrochloride in human subjects. The primary skin irritation potential of glycinamide hydrochloride was evaluated by patch testing in 30 human subjects. The skin depigmentation efficacy of glycinamide hydrochloride was evaluated in a double-blinded clinical test in 21 human subjects. The test product and a control product were applied to designated sites on the right or left side of the face twice daily for eight weeks. Skin color parameters, i.e., the melanin index, the L* value (representing skin lightness), a* value (redness), and b* value (yellowness) were measured using instruments. The individual topology angle (ITA^o, representing skin color) was calculated from L* and b values. The degree of skin pigmentation was visually assessed by two testers. The primary skin irritation test showed that a solution containing glycinamide hydrochloride up to 10% did not induce any adverse skin responses. In the efficacy test, the test product significantly reduced the melanin index, and increased L* value and ITA^o after two weeks of application relative to the baseline value at the start of the test. It also significantly lowered the degree of pigmentation after 6 weeks of application, relative to the baseline value. Differences in the melanin index, L* value, ITA^o and the degree of pigmentation between the test and control groups became statistically significant after six weeks or eight weeks of application. No signs of skin irritation were observed during the efficacy test. The present study suggests that glycinamide hydrochloride has great potential to be used in the control of skin hyperpigmentation.

Keywords: depigmenting; glycinamide hydrochloride; melanin; peptide; pigmentation; skin lightening; whitening.

Abstract

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