2.6. Melanogenesis Assay on Human and Mouse Melanocytes
B16 cells (CRL-6323™; American Type Culture Collection (ATCC), Manassas, VA) and A375 cells (CRL-
1619™, ATCC) were purchased from ATCC and cultured according to the recommendations provided. B16 and
A375 cells were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with 10% fetal bovine
albumin and Penicillin-Streptomycin (100 U/mL). Cells were sub-cultured every alternate day.
For melanogenesis assay, two hundred thousands of B16 cells and A375 cells were seeded onto each well of
6-well culture plates and incubated for 2 days, or 4 days, with or without the extracts of EBN, respectively. Five
mM of vitamin C, 50 μM of tBHQ and 2% kojic acid served as positive controls. For A375 cells, α-MSH was
added on day 2 as to stimulate the formation of melanin. To extract melanin from cells, the samples were dissolved
in 100 mL of 1 M NaOH after washing twice with PBS. Samples were incubated at 60˚C for 1 hour and
mixed to solubilize the melanin. The optical density of mixed solution was detected at 405 nm, and the absorbance
was converted to melanin concentration by a standard curve.