Protection against free radicals (UVB irradiation) of a water-soluble enzymatic extract from rice bran. Study using human keratinocyte monolayer and reconstructed human epidermis

The antioxidant capacity of a water-soluble enzymatic extract from rice bran (EERB) has been tested in two cell models: keratinocyte monolayers and human reconstructed epidermis. Cells were incubated in culture medium in presence of different amounts of EERB and were UVB irradiated. Cell population assessment (MTT assay) and MDA (malonaldehyde) production were evaluated. The EERB did not induce cytotoxic effect for concentrations inferior or equal to 100 μg/mL. Human keratinocyte monolayers were protected of irradiation preventing 33% the lipid peroxidation process at concentration of 10 μg/ml of EEBR. In reconstructed human epidermis, 100 μg/mL decreased lipid peroxidation process by 44% (p < 0.01) with regards to irradiated negative control. This effect was comparable to that of vitamin E at 600 μg/mL. Our data indicate that EERB is potentially able to efficiently counteract UVB-induced response. The EERB, diluted at 10% with water has very good skin compatibility. This product showed a sun protection factor of 4.8 ± 0.3. Thus we can propose EERB as a useful natural standardized extract in skin photoprotection with promising applications in the field of dermatology.