Kimihisa Itoh

Melanin Hyperpigmentation Inhibitors from Natural Resources

In Oriental countries, such as China, Korea and Japan, a female beauty criterion since ancient times has been a face with fair skin, and the admiration of women with young, healthy, bright and fair skin has created a whitening cosmetics market. The color of human skin and hair is determined by a number of factors. Biosynthesis of the melanin pigment, namely melanogenesis, is the most important factor. Melanogenesis is a multistage process involving melanin synthesis, melanin transport, and melanosome release. Tyrosinase is one of the key enzymes in the melanin biosynthetic pathway. Abnormal deposition of the melanin pigment causes hyperpigmentary disorders. From natural sources, a number of ingredients with an inhibitory effect on melanin hyperpigmentation have been found, and some of them were developed as cosmetic agents and over the counter (OTC) drugs in Oriental countries. On the other hand, some medicinal chemists have recently paid a lot of attention to inhibitors of melanin production to prevent hyperpigmentary disorders such as melasma, freckles and age spots. To develop novel and useful cosmetic agents, supplements, functional foods and OTC drugs, we have continued to research regulators of melanin production from natural sources since 1980. We describe here our screening strategy and studies on targeted melanin hyperpigmentation inhibitors from natural plant sources, e.g. Umbelliferae, Ericaceae, Rubiaceae, Piperaceae and Rutaceae plants. Interesting findings originating from the screening results are also described.