Cinnamic acid, a naturally occurring aromatic fatty acid of low toxicity, has a long history of human exposure. The cinnamic acid induces cytostasis and a reversal of malignant properties of human tumor cells in vitro. The cinnamic acid was found to induce cell differentiation as evidenced by morphological changes and increased melanin production in melanoma […]

Traditional Chinese herbs are a very popular mode for the treatment of hyperpigmentation disorders. Two hundred nineteen kinds of herbs have been screened; among them 19 kinds have been shown to inhibit tyrosinase in vitro (64). The inhibitory effects of tyrosinase activity of Atractylodes macrocephala, Bombyx mori, Ligusticum sinense, Bletilla striata, Typhonium giganteum, Astragalus complanatus, […]

Linoleic acid in vivo showed the greatest lightening effect in UVB-induced pigmentation, without toxic effects on melanocytes (53). Several protease inhibitors caused the accumulation of an approximately 60 kDa tyrosinase doublet promoted the translation of the enzyme to melanosomes (60). The evidence suggests that tyrosinase in selectively targeted by fatty acids, which seem to act […]

The benefits of AHAs have long been recognized. Sour milk [contains lactic acid (LA)] and sugarcane juice [contains glycolic acid (GA)] were applied to the face. In low concentrations, AHAs decreased corneocyte cohesion, leading to sloughing of dead cells and stimulation of new cell growth in the basal layer. In higher concentrations, they cause epidermilysis. […]

The capacity of several compounds to disperse melanin pigment and/or accelerate epidermal turnover can result in skin lightening. Chemical substances used as exfoliates, such AHAs, free fatty acids, and retinoic acid, stimulate cell renewal facilitating the removal of melanized keratinocyte, leading to melanin granules loss (53). Topical application has been shown to reduce the visibility […]

Soybean trypsin inhibitor (STI) inhibited PAR-2 cleavage, and completely inhibited the UVB-induced pigmentation of the epidermal equivalents containing melanocytes (50). Treatment with STI resulted in significant depigmentation, and reduced pigment deposition within the swine epidermis and prevented UVB-induced pigmentation in vivo. STI reduced keratinocyte ingestion of microspheres or E. coli particles (48). STI-treated cells showed […]

RWJ-50353, a serine protease inhibitor that reduced melanosome uptake in culture, is shown to have a dose-dependent depigmenting activity in vivo with no irritation or other side effects. Treatment with increasing concentrations of RWJ-50353 did not affect tyrosinase mRNA levels. Interestingly, this treatment led to decreased levels of TRP-1 and increased levels of TRP-2 mRNAs […]

Niacinamide or nicotinamide is a biologically active form of niacin (vitamin B3) involved in over 200 enzyme reactions in the form of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. Hakozaki et al. (51) suggested that niacinamide has no effect on tyrosinase activity, melanin synthesis, or cell number in melanocyte monoculture system, and no effect […]

The activation of protease-activated receptor-2 (PAR-2), a seven trans-membrane G-protein coupled receptor, which is expressed in keratinocytes and not in melanocytes, was found to activate keratinocyte phagocytosis, enhancing the melanosome transfer (48). Inhibition of PAR-2 cleavage by serine protease inhibitor, such as RWJ-50353, completely avoids the UVB-induced pigmentation of epidermal analogs (49,50).