Sesquiterpene fractions of Artemisia plants as potent inhibitors of inducible nitric oxide synthase and cyclooxygenase-2 expression.

OBJECTIVES: Artemisia species are important medicinal plants throughout the world. Some species are traditionally used for their anti-inflammatory effect. The present study was designed to isolate sesquiterpene fractions from several Artemisia species and evaluate their anti-inflammatory activities on key mediators and signaling molecules involved in regulation of inflammation. MATERIALS AND METHODS: Sesquiterpene fractions were prepared from several Artemisia species using the Herz-Högenauer technique. Lipopolysaccharide (LPS)-stimulated J774A.1 macrophages were exposed to isolated fractions. Their possible cytotoxic effect was examined using MTT assay. In addition, nitric oxide (NO) release was measured using Griess method and prostaglandin E2 (PGE2) level was determined by enzyme-linked immunosorbent assay (ELISA). Moreover, protein expression of pro-inflammatory enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were investigated using Western blot analysis. RESULTS: Nitric oxide level produced by LPS-primed macrophages was significantly decreased with all prepared fractions in a dose-dependent manner. Saturated sesquiterpene lactones-rich species (Artemisia kopetdaghensis, Artemisia santolina, Artemisia sieberi) showed the highest suppressive activity on NO and PGE2 production via suppression of iNOS and COX-2 expression. Fractions bearing unusual (Artemisia fragrans and Artemisia absinthium) and unsaturated sesquiterpene lactones (Artemisia ciniformis) possess less modulatory effect on PGE2 production and COX-2 expression. CONCLUSION: It can be concluded that some of the medicinally beneficial effects attributed to Artemisia plants may be associated with the inhibition of pro-inflammatory signaling pathways. However, these effects could be dependent on the type of their sesquiterpene content. These findings also introduce new Artemis species cultivated in Iran as a useful anti-inflammatory agents.

St. John's wort and its component hyperforin alleviate experimental autoimmune encephalomyelitis through expansion of regulatory T-cells.

Multiple sclerosis (MS) is a central nervous system disorder mainly characterized by inflammation, demyelination and axonal injury. Anti-inflammatory agents can be used to ameliorate the disease process. Hypericum perforatum L or St. John's wort is widely used as an anti-depressant and anti-inflammatory remedy in traditional and herbal medicine. Based on St. John's wort properties, the therapeutic potentials of an H. perforatum extract (HPE) and a single component, hyperforin were evaluated for effectiveness against MOG35-55-induced experimental autoimmune encephalomyelitis (EAE), an animal model for human multiple sclerosis. Female C57BL/6 mice were immunized with specific antigen MOG35-55 and then administered different doses of hyperforin or HPE post-immunization. Clinical symptoms/other relevant parameters were assessed daily. Histological analysis of the spinal cord was performed. T-cell proliferative activity was also evaluated using a BrdU assay. The effect of hyperforin on regulatory T-cells (Treg cells) was assessed using flow cytometry. The results indicate hyperforin and HPE reduced the incidence and severity of EAE, an outcome that closely correlated with an inhibition of pathological features (leukocyte infiltration and demyelination) and antigen-specific T-cell proliferation. The study also showed that hyperforin caused increased Treg cell levels in the spleen. These results indicated that hyperforin and HPE could attenuate EAE autoimmune responses by inhibiting immune cell infiltration and expansion of Treg cell and could eventually be considered as a potential candidate for use in the treatment of MS.