The roots and rhizomes of Nardostachys chinensis have neuroprotection and cardiovascular protection effects. However, the specific mechanism of N. chinensis is not yet clear. Nardochinoid C (DC) is a new compound with new skeleton isolated from N. chinensis and this study for the first time explored the anti-inflammatory and anti-oxidant effect of DC. The results showed that DC significantly reduced the release of nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-activated RAW264.7 cells. The expression of pro-inflammatory proteins including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were also obviously inhibited by DC in LPS-activated RAW264.7 cells. Besides, the production of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were also remarkably inhibited by DC in LPS-activated RAW264.7 cells. DC also suppressed inflammation indicators including COX-2, PGE2, TNF-α, and IL-6 in LPS-stimulated THP-1 macrophages. Furthermore, DC inhibited the macrophage M1 phenotype and the production of reactive oxygen species (ROS) in LPS-activated RAW264.7 cells. Mechanism studies showed that DC mainly activated nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway, increased the level of anti-oxidant protein heme oxygenase-1 (HO-1) and thus produced the anti-inflammatory and anti-oxidant effects, which were abolished by Nrf2 siRNA and HO-1 inhibitor. These findings suggested that DC could be a new Nrf2 activator for the treatment and prevention of diseases related to inflammation and oxidative stress.

Sinomenine (SIN), an alkaloid derived from the plant Sinomenium acutum, has anti-inflammatory and analgesic effects and has been used for rheumatoid arthritis treatment in China. This study aims to verify the hypothesis that SIN acts on α7 nicotinic acetylcholine receptor (α7nAChR) to inhibit the activation of macrophages stimulated by lipopolysaccharide. The prototypical α7nAChR antagonist α-bungarotoxin and mecamylamine attenuated the effect of SIN on tumor necrosis factor-α and interleukin-6 in RAW264.7 murine macrophage-like cells and primary peritoneal macrophages of mouse induced by lipopolysaccharide. With the knockdown of α7nAChR expression in RAW264.7 cells by small interfering RNA, the inhibitory effect of SIN on tumor necrosis factor-α and interleukin-6 was reversed. Sinomenine decreased p65 expression in nuclear and increased IκBα expression in cytoplasm, and these effects were reversed by the α7nAChR small interfering RNA as well. These results indicate that the anti-inflammatory effects of SIN on macrophages in vitro depend on α7nAChR.

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