RESUMO
BACKGROUND: The expression of heat shock proteins (HSPs), particularly HSP70, is receiving considerable attention in the field of cosmetics, particularly given our recent report that ultraviolet-induced melanin production, skin damage and wrinkle formation were all suppressed in transgenic mice expressing HSP70. OBJECTIVE: In the present study, we searched for HSP70-inducers from a library of herbal extracts that have already been approved as quasi-pharmaceutical products in Japan. We selected an ethanol extract of Arnica montana (A. montana), based on its high HSP70-inducing activity and low cytotoxicity. METHODS: Cell viability was determined by MTT method and expression of HPS70 was monitored by immunoblotting analysis. RESULTS: From the extract, we purified and identified eight sesquiterpene lactones (AM1-8) as HSP70-inducers, among which AM-2 (helenalin 2-methylbutyrate) was selected due to its good HSP70-inducing properties and low cytotoxicity. Treatment of cultured mouse melanoma cells with AM-2 or A. montana extract up-regulated the expression of HSP70 in a dose-dependent manner. This treatment also activated heat shock factor-1, a transcription factor for hsp genes. Furthermore, pre-treatment of cells with AM-2 or A. montana extract decreased melanin production and expression and activity of tyrosinase. CONCLUSION: These results suggest that AM-2 and A. montana extract could be beneficial for use in hypopigmenting cosmetics as a consequence of their stimulatory effects on HSP70 expression.
Assuntos
Arnica , Proteínas de Choque Térmico HSP70/metabolismo , Extratos Vegetais/farmacologia , Preparações Clareadoras de Pele/farmacologia , Pigmentação da Pele/efeitos dos fármacos , Pele/efeitos dos fármacos , Animais , Arnica/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Etanol/química , Melaninas/biossíntese , Melanoma Experimental , Camundongos , Monofenol Mono-Oxigenase/metabolismo , Fitoterapia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Plantas Medicinais , Pele/metabolismo , Pele/patologia , Preparações Clareadoras de Pele/química , Preparações Clareadoras de Pele/isolamento & purificação , Solventes/química , Regulação para CimaRESUMO
Skin hyperpigmentation disorders as a result of abnormal melanin production induced by ultraviolet (UV) irradiation are both a clinical and a cosmetic problem. This melanin production is mediated by tyrosinase whose expression is positively regulated by microphthalmia-associated transcription factor (MITF). We recently found that expression of heat shock protein 70 (HSP70) inhibits melanin production. In this study, we searched for HSP70 inducers from Chinese herbs and selected an ethanol extract of Eupatorium lindleyanum (E. lindleyanum). Not only melanin production but also the activity and expression of tyrosinase were significantly suppressed in cells treated with E. lindleyanum extract as well as in HSP70-overexpressing cells. The expression of MITF was clearly suppressed in cells treated with E. lindleyanum extract but not in HSP70-overexpressing cells. These results suggest that E. lindleyanum extract suppresses the expression of tyrosinase and melanin production through both HSP70-dependent and HSP70-independent mechanisms.