Chulalongkorn Medical Journal


Background : A previous study on the inhibitory effects of Rhinacanthus nasutus (L.)Kurz leaf ethanol extract on mushroom tyrosinase activity indicated that itcontains anti-melanogenesis properties. However, other solvents especiallywater had not been investigated with regards to their use as a skin whiteningagent.Objective : To investigate the inhibitory effect R. nasutus leaf water extract onmelanogenesis in B16F10 melanoma cells.Methods R. nasutus leaf was extracted with water and a determined amount ofthe phenolic and flavonoid contents by using Folin-Ciocalteu and aluminiumchloride colorimetric assay, respectively. The toxicity of R. nasutus leafextract in B16F10 melanoma cells was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Its potential onmelanogenesis inhibition was determined by melanin content assay andtyrosinase activity assay. Data were analyzed by using SPSS.Results : R. nasutus leaf extract have a total phenolic content of 35.75 ± 0.30 mggallic acid equivalents per gram of extract and flavonoid of 19.17 ± 0.00 mgrutin equivalent per of extract. We found that R. nasutus leaf extractdecreased the melanin content and intracellular tyrosinase activity inB16F10 melanoma cells without any cytotoxicity.Conclusion Our results indicate that R. nasutus leaf water extract inhibited the melaninproduction by downregulating tyrosinase activity. Thus it might prove tobe useful as a therapeutic treatment for skin hyperpigmentation disordersand an effective component of whitening cosmetics.


Faculty of Medicine, Chulalongkorn University

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