Chronic exposure to solar ultraviolet (UV) light causes skin photoaging. Many studies have shown that
naturally occurring phytochemicals have anti-photoaging effects, but their direct target molecule(s) and
mechanism(s) remain unclear. We found that myricetin, a major flavonoid in berries and red wine,
inhibited wrinkle formation in mouse skin induced by chronic UVB irradiation (0.18 J/cm2
, 3 days/week
for 15 weeks). Myricetin treatment reduced UVB-induced epidermal thickening of mouse skin and also
suppressed UVB-induced matrix metalloproteinase-9 (MMP-9) protein expression and enzyme activity.
Myricetin appeared to exert its anti-aging effects by suppressing UVB-induced Raf kinase activity and
subsequent attenuation of UVB-induced phosphorylation of MEK and ERK in mouse skin. In vitro and in
vivo pull-down assays revealed that myricetin bound with Raf in an ATP-noncompetitive manner.
Overall, these results indicate that myricetin exerts potent anti-photoaging activity by regulating MMP-
9 expression through the suppression of Raf kinase activity