The use of phytochemicals for preventing chronic diseases associated with oxidative stress such as cataracts is hindered by their low bioavailability. The effects of nano-carriers on the antioxidant activities of extracts of black rice with giant embryo (BRGEx) and soybeans (SBx) have been determined in human lens epithelial B3 cells. Scanning (SEM) and transmission electron microscopy (TEM) demonstrated that rGO (reduced graphene oxide) has a flat surface unlike GO (graphene oxide), which has a distinctive wrinkled structure with defects. UPLC analysis revealed 41.9 μg/100 g of γ-oryzanols in water extract of BRGE, and 111.8 μg /100 g of lutein, 757.7 μg/100 g of γ-tocotrienol, 4071.4 μg/100 g of γ-tocopherol in 40% ethanol extract of soybeans, respectively. Even though a low concentration of BRGEx alone did not show any antioxidant activity in B3 cells, co-treatment of BRGEx with rGO together substantially reduced hydrogen peroxide and methylglyoxal-induced DNA damage, as determined by phosphorylated γH2AX. In addition, SBx with rGO also attenuated DNA damage. Furthermore, intracellular reactive oxygen species were significantly decreased by combining extracts of these colored grains with rGO. These results suggest a potential application of nanocarriers for enhancing the bioavailability of phytochemicals.
Keywords: bioavailability; black rice with giant embryo; oxidative DNA damage; reduced graphene oxide; γH2AX.