2.7. Melanin Content and Cell Viability Analyses

B16F10 melanoma cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum, 100 U/mL penicillin and 100 μg/mL streptomycin in an incubator containing 5% CO₂ at 37 °C.

The inhibitory effect of each sample on α-MSH-induced melanin contents in B16F10 cells was analyzed as described by Jin et al. [22]. The B16F10 cells were exposed to 50 µg/mL of each sample or DMSO (as a mock control) with 50 nM α-MSH for 48 h. After harvesting the cells, the cell pellets were solubilized in 1 N NaOH containing 10% DMSO at 65 °C for 1 h, after which the absorbance was measured at 490 nm. The melanin contents were expressed as percentages of the mock control. Furthermore, the viability of α-MSH-stimulated B16F10 cells treated with each sample or DMSO was determined via the MTT assay [22].

The in vitro inhibitory effects of each sample against tyrosinase activity were determined using the Tyrosinase Inhibitor Screening Kit (BioVision, Milpitas, CA, USA).