Hibiscus Flower Extract and Niacinamide Show Enhanced Whitening Effects in Mouse Melanoma Cells (B16F10)

Melanoma, a type of cancer that most often occurs on skin exposed to UV rays, is becoming increasingly common. Recent research has focused actively on using natural products. The goal of this study was to compare the melanin-inhibitory effects of Hibiscus (Hibiscus sabdariffa L.) flower Extract (HE) and Niacinamide (NA), a functional ingredient with whitening effects, on melanoma cells. The 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the effects of HE (1, 3.5, 7, 10, and 14 μg/mL) and NA (1, 5, 10, 20, and 25 μg/mL) on cell viability. A lactate dehydrogenase cytotoxicity assay was employed to confirm the cytotoxic effect of HE and NA on mouse melanoma cells. The real-time reverse-transcription polymerase chain reaction was performed to analyze Tyrosinase (TYR), Tyrosinase-Related Protein (TRP), and Microphthalmia-associated Transcription Factor (MITF) mRNA expression levels to determine whitening effects. Vitamin C (VC, 10 µg/mL) was selected as a control. The MTT assay showed that HE and NA were non-cytotoxic at <10 μg/mL in B16F10 cells when compared to the control, VC. The cytotoxicity of HE was confirmed to be lower than the control (VC) when a concentration of 7 µg/mL or lower was applied. The cytotoxicity of NA was low even at a concentration of 10 µg/mL. HE showed greater whitening effects at lower concentrations (i.e., 1 µg/mL) than VC (10 µg/mL). HE had almost no cytotoxicity compared to NA and VC, and the expression levels of whitening inhibition genes MITF and TYR were higher than VC, indicating that it can be used as a healthy functional food or cosmetic material.