Inhibition of UVB-induced Skin Phototoxicity by a Grape Seed Extract As Modulator of Nitrosative Stress, ERK/NF-kB Signaling Pathway and Apoptosis, in SKH-1 Mice

Molecular mechanisms concerning the modulation of nitrosative stress, signal transduction and proliferation/apoptosis by a grape seed extract, Burgund Mare variety (BM), in SKH-1 mice exposed to UVB, were investigated. The animals were irradiated with single and multiple doses of UVB in 10 consecutive days. In each experiment were used five groups of animals: control, vehicle, UVB irradiated, vehicle+UVB, BM+UVB. The extract was applied topically, 30 min before each UVB exposure, in a dose of 4 mg total polyphenols/cm(2). BM remarkably inhibited UVB-induced activation of inducible nitric oxide synthase (iNOS) and therefore generation of nitric oxide (NO) and nitrotyrosine, in a UVB single dose regimen. BM also suppressed NF-kB activation by UVB but did not affect the activity of total ERK 1/2. In multiple UVB irradiations, BM increased NO formation and total ERK 1/2 activity and reduced iNOS activity and nitrotyrosine levels, inhibited cell proliferation, diminished p53 and caspase-3 immunoreactivities and increased the percentage of Bcl-2 positive cells. We concluded that BM modulates the apoptotic response of SKH-1 mice skin in UVB irradiation by the inhibition of p53, caspase-3, Bax/Bcl-2 and proliferating cell nuclear antigen expressions, as well as by reducing the activation of iNOS and NF-kB.