Inhibitory effect of Rhinacanthus nasutus (L.) Kurz leaf extract on melanogenesis in B16F10 melanoma cells

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Benjamart Pratoomthai
Warachin Gangnonngiw
Jarinyaporn Naowaboot
Thanitsara Songtavisin


Background : A previous study on the inhibitory effects of Rhinacanthus nasutus (L.) Kurz leaf ethanol extract on mushroom tyrosinase activity indicated that it contains anti-melanogenesis properties. However, other solvents especially
water had not been investigated with regards to their use as a skin whitening agent.

Objective : To investigate the inhibitory effect R. nasutus leaf water extract on melanogenesis in B16F10 melanoma cells.

Methods : R. nasutus leaf was extracted with water and a determined amount of the phenolic and flavonoid contents by using Folin-Ciocalteu and aluminium chloride colorimetric assay, respectively. The toxicity of R. nasutus leaf extract in B16F10 melanoma cells was tested by 3-(4,5-dimethylthiazol-2- yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Its potential on melanogenesis inhibition was determined by melanin content assay and tyrosinase activity assay. Data were analyzed by using SPSS.

Results : R. nasutus leaf extract have a total phenolic content of 35.75 gif.latex?\pm 0.30 mg  gallic acid equivalents per gram of extract and flavonoid of 19.17 gif.latex?\pm 0.00 mg rutin equivalent per of extract. We found that R. nasutus leaf extract decreased the melanin content and intracellular tyrosinase activity in B16F10 melanoma cells without any cytotoxicity.

Conclusion : Our results indicate that R. nasutus leaf water extract inhibited the melanin production by downregulating tyrosinase activity. Thus it might prove to be useful as a therapeutic treatment for skin hyperpigmentation disorders
and an effective component of whitening cosmetics.

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