John W. Quigley, Kurt Blanock, Koichiro Kameyama, Shigeo Kondo, Daniel Bucks, Kozo Yonemoto, Albert M. Dorsky, Masato Tagawa, Murata Tomoji, Toshio Onuma, and Chie Sakai
The inhibitory effects of magnesium ascorbyl phosphate (VC-PMG) on melanogenesis were investigated in vitro using purified tyrosinase, B16F10 murine melanoma cell extract, and KHm-1/4 human melanoma cells. VC-PMG inhibited tyrosinase activity at a concentration of more than 0.001% for the purified tyrosinase, at a concentration of more than 0.01% for the B16F10 murine melanoma cells extract, and at a concentration of 0.1% for the KHm-1/4 human melanoma cells.Percutaneous absorption of 14C-labeled VC-PMG was examined by applying creams containing 3% VC-PMG onto dermatomed human cadaver skin. After 48 hours, VC-PMG was retained in the skin at levels of less than 2% of the applied dose.The lightening effects of VC-PMG on hyperpigmentation disorders, such as ephelides, chloasma, and senile freckle, in human skin in vivo were also studied. Cream containing 10% VC-PMG was applied to the pigmented area of 34 patients' faces twice a day for three months. Measurement by a color difference meter showed that the color of those pigmentations for 26 patients was lightened due to the topical application of VC-PMG cream. VC-PMG cream was also applied to non-pigmented area of 27 out of 34 patients. VC-PMG cream was also effective in lightening on 11 out of 27 healthy skin.These results suggested that VC-PMG was absorbed by topical application, and stayed in the skin, and inhibited tyrosinase activity of melanocytes. In vivo results clearly showed that topical application of VC-PMG can be effective in lightening human skin pigmentations.