Inhibitory effect of water extract of Sophora flavescens on inflammation and oxidative stress through activating Nrf2/HO-1 signaling pathway / 中草药

ABSTRACT

Objective: To study the molecular mechanisms of antioxidant effect and anti-inflammatory of water extract of Sophora flavescens (WSF) in lipopolysaccharide (LPS)-induced RAW264.7 cells. Methods: The optimum concentration of WSF was evaluated by CCK-8 assay. The inflammatory model was established with LPS by stimulating RAW264.7 cells in vitro. Then all cells were divided into control group, model group, WSF group and WSF control group. The levels of ROS and NO were analyzed with flow cytometry. Subsequently, the expression of iNOS, COX-2, Nrf2, and HO-1 was detected with qRT-PCR and Western blotting. Finally, the pro-inflammatory cytokines IL-6, TNF-α and anti-inflammatory cytokine IL-10 were detected by ELISA. Results: The CCK-8 assay revealed that 0.01 mg/mL WSF did not affect the cell viability. Compared with control group, the LPS-induced inflammatory response could significantly increase the production of NO and ROS, and the IL-6 and TNF-α were also significantly increased (P < 0.05, 0.01, and 0.001). Furthermore, the expression of iNOS and COX-2 were significantly increased (P < 0.01, 0.001), but the expression of Nrf2 and HO-1 were inhibited (P < 0.05). However, compared with model group, the WSF group not only significantly decreased the levels of NO, ROS, IL-6, and TNF-α, but also decreased the expression of iNOS and COX-2 (P < 0.05, 0.01, and 0.001). In contrast, the the level of IL-10 and the expression of Nrf2 and HO-1 were significantly increased (P < 0.05, 0.01, and 0.001). Conclusion: These results suggested that SF exerted protective effect against LPS-induced inflammatory and oxidative responses in RAW 264.7 cells by the activation of the Nrf2/HO-1 pathway.