龍葵葉子水萃物作用於鼠類巨噬細胞株RAW 264.7之抗發炎機制探討

Abstract

Solanum nigrum Linn (SNL), a member of the Solanaceae family , is a common herb that grows wildly and abundantly in open fields .Traditionally, it has been used in chinese medicine for curing inflammatory disease and various kinds of cancers. Approximately, 25 % of all cancers are somehow associated with chronic infection and inflammation. Chronic inflammation is considered as a possible mechanism in initiating tumorigenesis, resulting from the generation of ROS (Reactive Oxygen Species)/RNS (Reactive Nitrogen Species) by macrophages in the inflamed tissue and resulted in DNA damage. Chronic dysregulated activation of some cellular ROS/Eicosanoid generating enzymes, NOX-2 (NADPH Oxidase-2), XO (Xanthine Oxidase),iNOS (inducible Nitric Oxide Synthase) and COX-2 (Cyclooxygenase-2), have been shown to play pivotal roles during this process. The signal transduction pathways related to these enzymes in macrophages mainly including NF-κB/AP-1/MAPK pathway. Thus, to study the mechanism of the potential agents with anti-inflammatory activities might be important in the effects of chemoprevention of chronic inflammation and carcinogenesis. The main aim of this study is to evaluate the anti-oxidant and anti-inflammatory effects about Solanum nigrum Linn water extracts (SNE). Using the xanthine oxidase activity assay, we found that the stem water extracts of SNL didn't inhibit xanthine oxidase activity, but only the leaf and green fruit water extracts of SNL demonstrate the inhibitory activity. We also used the nitrite assay to investigate the inhibition ability of SNL on the nitrite released in culture medium of LPS-stimulated RAW 264.7 cells. We found that only the leaf and green fruit water extracts of SNL effectively inhibited the nitrite excretion. Additionally, the leaf water extracts of SNL effectively inhibited the ROS production in LPS-stimulated RAW 264.7 cells, but the stem and fruit water extracts of SNL didn’t. These results suggested that the leaf water extracts of SNL might exert the anti-inflammatory actions by suppressing NO and ROS production and xanthine oxidase activity. Moreover, we used western blot to investigate the inhibition ability of the leaf water extracts on the cellular inflammatory signal transduction pathway . The data demonstrated that the leaf water extracts greatly inhibited the p38/JNK MAPK activity , and also had the ability to decrease the NF-κB (p65)/AP-1 (phospho c-jun) nuclear translocation level. Then, we used RT-PCR to assay the iNOS mRNA expression, indicating that the leaf water extracts could inhibit iNOS mRNA expression dose-dependently.