Inhibitory effect of magnesium L-ascorbyl-2-phosphate (VC-PMG) on melanogenesis in vitro and in vivo

Background: An inhibitory effect of ascorbic acid (AsA) on melanogenesis has been described. However, AsA is quickly oxidized and decomposed in aqueous solution and thus is not generally useful as a depigmenting agent. Objective: Our purpose was to examine the effect on pigmentation of magnesium-L-ascorbyl-2-phosphate (VC-PMG), a stable derivative of AsA. Methods: Percutaneous absorption of VC-PMG was examined in dermatomed human skin, and its effect on melanin production by mammalian tyrosinase and human melanoma cells in culture was also measured. A 10% VC-PMG cream was applied to the patients. Results: VC-PMG suppressed melanin formation by tyrosinase and melanoma cells. In situ experiments demonstrated that VC-PMG cream was absorbed into the epidermis and that 1.6% remained 48 hours after application. The lightening effect was significant in 19 of 34 patients with chloasma or senile freckles and in 3 of 25 patients with normal skin. Conclusion: VC-PMG is effective in reducing skin hyperpigmentation in some patients.