Progressiye Effects of Phlor ; dzinon Melanogenesis in B 16 Mouse Melanoma Cells

When we studied the effects of polyphenols froin apple fruits on melanogenesis in Bl6 mouse melanoma eell lines, phloridzin had dose-dependent progressive effects on melanogenesis between 10 and 500"g/ml without inhibiting cell grewth. At a concentration of 500pg/ml, phloridzin increased the melanin content in the cells to 181Y, of that in control cells. In contrast, phloretin, the aglycon gf phloridzin, did not ttctiyate melanogenesis in the cells and was cytetoxic at a concentratien of 5 "g/ml. Phloridzin increased the activity of tyrosinftse to 223% of that in control ce)ls. Furtherrnore, phloridzin inhibited the actiyity of protein kinase C (PKC), which is recognized to regulate tyresinase actiyity. The inhibition f PKC activity continued for 120min from the addition of phleridzin. Therefore, we estimated that the actiyation of me}anegenesis by ph}oridzin resu]ted from the incTease of tyrosinase a ¢ tivity caused b)' the inhibition f PKC actiyity.