Roles of Aqueous Extract of Marigold on Arsenic-Induced Oxidative Damage in Pancreatic Islet β-Cells

Roles of Marigold extracts (ME) on arsenic trioxide (ATO)-induced oxidative damage to pancreatic β-cells need to be further elucidated. In this study, NIT-1 cells were treated with different concentrations of and/or ATO, following by the cell viability was detected by CCK8 assay. Then, intracellular reactive oxygen species (ROS) levels, lipid peroxide (MDA) contents and superoxide dismutase (SOD) activity were measured with a fluorescence probe method and colorimetric assay, respectively. The apoptosis rate and morphology was detected and observed with hoechst 33,258 staining assay. The mRNA levels and protein expressions of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were measured by real-time fluorescence quantitative polymerase chain reaction and protein immunoblotting assay, respectively. Our results indicated that Co-treatment with ME and ATO exacerbated the cell viability decreasing reduced by ATO, while the addition of ME after ATO treatment effectively promote the recovery of ATO reduced survival rates. The ATO group increased apoptosis (P < 0.05), while the ATO ME-treated group alleviated apoptosis caused by ATO (P < 0.05); ROS content was 1.49 and 1.26 times higher in the ATO and ATO ME groups, respectively, compared with the control group; SOD activity in the ATO group (69.66 ± 1.97 U/mg Protein) was significantly lower than that in the SOD activity in the ATO group (69.66 ± 1.97 U/mg Protein) was significantly lower than that in the control group (85.18 ± 4.57 U/mg Protein) and the ATO ME group (76.82 ± 2.30 U/mg Protein); MDA content in the ATO group (3.78 ± 0.22 nmol/mg protein) was significantly higher than that in the control group (2.71 ± 0.21 nmol/mg protein) and the ATO ME group (3.13 ± 0.19 nmol/mg protein); the mRNA levels of HO-1 and Nrf2 were elevated in the ATO group and ATO ME-treated group compared with the control group, and the trends of protein expression levels of HO-1 and Nrf2 were consistent with the trends of mRNA levels. The results of this study suggest that aqueous extracts of Marigold may be involved in antagonizing arsenic-induced oxidative damage in pancreatic β-cells by modulating the activation of the Nrf2 signaling pathway.