In the flora of Turkey, the genus Veronica L. (Scrophulariaceae) is represented by 79 species, 26 of which are endemic.1) In traditional Turkish medicines, some Veronica species are used as diuretics and in the healing of wound.2) In addition, several Veronica species are used to treat cancer, influenza, hemoptysis, leryngopharyngitis, hernia, cough and respiratory diseases and are also used as an expectorant and antiscorbutic. [3][4][5] Veronica species contain mainly iridoid glucosides, especially benzoic and cinnamic acid esters of catalpol, some phenylethanoid and flavonoid glycosides. [6][7][8][9][10][11] However, there is no report on the action mechanism of this genus.In our continuous research on Turkish medicinal plants, we have tried to evaluate the biological and pharmacological activity of Veronica species using a bioassay-guided fractionation method. In the present study, focusing on anti-inflammatory and cytotoxic activities, we screened five Veronica species. Suppressive effects on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated macrophages were used to evaluate anti-inflammatory activity. Activated macrophages produce large amounts of important effector molecules that elicit inflammation. NO, a bioactive free radical, is one of these critical mediators which is produced by inducible NO synthase (iNOS) in inflammatory macrophages when stimulated with bacterial membrane components, LPS and cytokines.12) Although many studies have demonstrated that cytokine-induced NO production can damage parasites or tumor cells, NO is also linked to damage and death of normal cells.13) In fact, higher NO levels are demonstrated in patients with rheumatoid arthritis, systemic lupus erythematosous and inflammatory myositis, indicating that NO elicits and aggravates inflammation.14) The inflammatory effect of NO is mediated by its ability as a free radical and is associated with the increase in iNOS expression. Therefore, the suppressive effect on NO production in LPS stimulated macrophages is one of the useful indexes for evaluating antiinflammatory activity. The level of iNOS expression and the free radical scavenging ability mainly regulates NO level. In the present study, we assessed the anti-inflammatory effect of Veronica species by determining NO levels, iNOS expression and radical scavenging activity. Radical scavenging activity was evaluated using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging system. In this assay, antioxidants react with the stable free radical DPPH (which gives a strong absorption at 517 nm), resulting on the production of colorless 2,2-diphenyl-1-picryl hydrazine.
15)In addition, to find a novel activity of Veronica species, the cytotoxicity after treatment of tumor cells (KB and B16) with test fractions was determined using microculture tetrazolium assay.
16) MATERIALS AND METHODSReagents LPS (from Escherichia coli) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) were purchased from Sigma (St. Louis, MO, U.S.A.). Thioglycol...
