Inhibition of Nitric Oxide Production and Proinflammatory Cytokines by Several Medicinal

A number of medicinal plants have been used to treat variousimmunological diseases. Nitric oxide (NO) has an important regulatory role in thevarious types of inflammatory processes. To investigate the NO modulatoryactivity of the extracts of several medicinal plants native to Iran includingDracocephalum kotschyi, Linum persicum, Dionysia termeana, Salvia mirzayanii,Ferulago angulata and Euphorbia cheiradenia. The methanolic extracts ofthe plants were prepared and examined for their effects on the NO production bylipopolysaccharide-stimulated mouse macrophages. The level of TNF-α and IL-1β proinflammatorycytokines in the macrophage culture were detected using enzyme-linkedimmunosorbent assay. All the extracts at concentration of 50 μg/mldemonstrated a significant decrease in NO production (p<0.001) after a 24-hourtreatment. This inhibitory effect was also seen after 48 hours. Among the extracts, L.persicum was the strongest extract in reducing the NO production at 1 μg/ml after both24 and 48-hours (nearly 100% inhibition, p<0.001). S. mirzayanii extract with 66.2 ±8% inhibition at 50 μg/ml, showed the mildest effects in 48 hour culture. In cytokinerelease determination, the extract of L. persicum significantly inhibited both TNF-α andIL-1β cytokines production by stimulated macrophages (p<0.001). D. kotschyi, D.termeana and F. angulata decreased secretion of IL-1β from the cells. These results indicate the presence of anti-inflammatory and macrophage inhibitorysubstances in these plants.