Masato Tagawa

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.

The Effects of Blending Hydrophobic Surfactants and Hydrophilic Surfactant on some Properties

Effects of blending homogeneous octaoxyethylene-monododecyl ether and pure lipophilic surfa ctants on cloud point (Cp), PIT and emulsifying properties have been studied. Cp is proportional to HLB value of mixture. The efficiency of PIT reduction is different with respect to structure of lipophilic surfactant, and the lower HLB lipophilic surfactans have smaller efficiency of PIT reduction. PIT is linearly decreased with increasing the fraction of MGS in mixture, and efficiency of PIT reduction is larger at high fraction of BL-3 SY in mixture. BL-2SY and DGS have better O/W emulsifying properties. (BL-nSY: homogeneous POE dode cylether, MGS: glyceryl mono-stearate, DGS: glyceryl di-stearate)