antioxidant effects of some medicinal plants

introduction: unsaturated fatty acids , one of the most important components of biological membranes , are very sensitive to oxidation processes. damage to cells and tissues by oxidation of these kinds of acids is one of the most important contributing  factors in many diseases, such as, atherosclerosis, rheumatoid arthritis and cancer. there are some available antioxidant synthetic compounds in market, but because of their side effects (toxic effects), they have not been used as antioxidant drug for now. medicinal plants, as the main natural sources of polyphenolic compounds, are interested for their antioxidant effects. the aim of this study is to examine the antioxidant effescts of some medicinal plants (of labiatae family) which are native to iran. materials and methods: the effects of hydroalcoholic extracts of six medicinal plants from labiatae family (salvia officinalis, melissa officinalis, thymus daenensis, dracocephalum kotschyi, lavandula angustifolia and dracocephalum moldavica) on decreasing oxidation of rats’ hepatocytes were investigated. these effects were  meseared by formation of mda and leakage value of sgot and ldl. results : this study indicated that, total extracts of salvia officinalis and melissa officinalis (with minimum concentration of 0.01mg/ml) and thymus daenensis and dracocephalum kotschyi (with minimum concentration of 0.05mg/ml) have more and better antioxidant effects. however, no antioxidant effects were seen from total extracts of lavandula angustifolia and dracocephalum moldavica. conclusion: it can be said that total extract of melissa officinalis has the best antioxidant effect among the six species which were investigated.