Hyperosmotic stress down-regulates melanin production.

<p>Hyperosmotic stress reduces melanin production but does not affect tyrosinase activity in MNT-1 cells. (A) MNT-1 cells were treated with 50 mM of the indicated sugar for 7 days, and the color of the cell pellets was monitored. NC, negative control. (B) The melanin content was measured at 450 nm. The data are representative of three independent experiments (***, P < 0.005). (C) Tyrosinase activity assay. MNT-1 cell extracts were incubated with 10 mM L-dihydroxyphenylalanine (L-DOPA), and the amount of melanin was measured at 450 nm. The data are representative of three independent experiments (N.S., not significant).