p-Coumaric acid as a skin whitening agent – Novel findings on its ability to attenuate melanin synthesis
p-Coumaric acid (p-CA) is a naturally occurring secondary metabolite of plants and its potential as a skin whitening agent attracts attention. p-CA was found to be a highly potent and selective inhibitor of human tyrosinase (TYR) compared to other well known TYR inhibitors such as arbutin and kojic acid. p-CA inhibited melanin synthesis in murine melanoma cells, human epidermal melanocytes and cultured 3-dimensional human skin equivalents. It also attenuated UVB-induced cytotoxicity. p-CA formulated in a cream permeated skin tissues ex vivo and its topical application mitigated UVB-induced inflammatory erythema and skin pigmentation in vivo in human skin. These findings support that p-CA has biochemical properties that make it suitable as a skin whitening ingredient in cosmetics.
Melanin is a major contributor to skin pigmentation and prevents UV-induced skin damage. However, its abnormal accumulation due to pathological or environmental factors causes aesthetic problems. In addition, many people prefer white or clean skin, and seek cosmetic products to decrease pigmentation. Thus, various ingredients such as arbutin and kojic acid have been incorporated into cosmetics in purpose of controlling unwanted skin pigmentation (1,2). However, their actual efficacies remain controversial and efforts to develop safer and more effective skin whitening ingredients continue. Here, we review recent studies on p-coumaric acid (p-CA) as a potential skin whitening agent for cosmetic use.
SKIN AND MELANIN
The skin is a vast organ that provides a barrier against mechanical, chemical and biological factors that have potentially harmful effects (3). The skin is composed of three major layers, which from outside to inside are the epidermis, dermis and hypodermis. Keratinocytes constitute most of the epidermal cells and melanocytes, Merkel cells and Langerhans cells make up the re ...