N-Nicotinoyl dopamine, a novel niacinamide derivative, retains high antioxidant activity and inhibits skin pigmentation.

We synthesized a novel derivative of a well-known skin-lightening compound niacinamide, N-nicotinoyl dopamine (NND). NND did not show inhibitory effects of tyrosinase and melanin synthesis in B16F10 mouse melanoma cells. However, NND retains high antioxidant activity without affecting viability of cells. In a reconstructed skin model, topical applications of 0.05% and 0.1% NND induced skin lightening and decreased melanin production without affecting the viability and morphology of melanocytes and overall tissue histology. Moreover, no evidence for skin irritation or sensitization was observed when 0.1% NND emulsion was applied onto the skin of 52 volunteers. The effect of NND on skin lightening was further revealed by pigmented spot analyses of human clinical trial. Overall, NND treatment may be a useful trial for skin lightening and treating pigmentary disorders.

Persicaria hydropiper (L.) spach and its flavonoid components, isoquercitrin and isorhamnetin, activate the Wnt/ß-catenin pathway and inhibit adipocyte differentiation of 3T3-L1 cells.

Obesity, which is related to metabolic syndrome and is associated with liver disease, represents an epidemic problem demanding effective therapeutic strategies. Evidence shows that the Wnt/ß-catenin pathway is closely associated with obesity and that small molecules regulating the Wnt/ß-catenin pathway can potentially control adipogenesis related to obesity. Eleven plant extracts activating the Wnt/ß-catenin pathway were screened by using HEK 293-TOP cells retaining the Wnt/ß-catenin signaling reporter gene. An extract of Persicaria hydropiper (L.) Spach was found to activate Wnt/ß-catenin signaling. P. hydropiper is grown worldwide in temperate climates and is found widely in Southeast Asia. The P. hydropiper extract inhibited the differentiation of adipocyte 3T3-L1 cells. Isoquercitrin and isorhamnetin, constituents of P. hydropiper, also activated Wnt/ß-catenin signaling and suppressed the differentiation of 3T3-L1 cells. These results indicate that isoquercitrin in P. hydropiper suppresses the adipogenesis of 3T3-L1 cells via the inhibition of Wnt/ß-catenin signaling. P. hydropiper and isoquercitrin may therefore be potential therapeutic agents for obesity and its associated disorders.