Radical scavenger and antioxidant activities of selected medicinal plants

Oxidative damage that results in lipid peroxidation can inactivate cellular components and can have serious effects on the cells, probably leading to ageing as well as several diseases. In recent years much attention has been focused on this subject, especially in the field of clinical medicine. Several natural compounds from plants exhibit antioxidant and/or radical scavenger properties. It also has become clear that the direct free radical scavenging effect and/or membrane protection play an important role in the action mechanism of several old established drugs. The natural antioxidant nutrients also deserve attention as they offer the possibility to replace the optimal overall antioxidant status. The aim of the present work was to prove the phytotherapeutical significance of some officinal and popular medicinal plants on the base of their antioxidant activity due to their influence on pathological free radical reactions. Experimental methods were planned and developed in order to measure the antioxidant, free radical scavenging, immunmodulant, membrane protecting activities and to monitor the cholesterol-, lipid peroxidation-lowering capacity of plant extracts and enriched/isolated fractions. Complex phytochemical screening and analytical standardization was carried out considering the potential bioactive constituents, which were determined by chromatographic and spectroscopic techniques. The non-specific scavenger activities of the medicinal plant extracts were studied by the chemiluminometric technique. Relationships were proved between the quantity / composition of active ingredients and scavenger activities of the individual extracts. Our results so far suggest that medicinal plants, their phytotherapeutical preparation or isolated constituents as supplements of human diets are promising as preventative agents when free radical reactions are involved in the pathogenesis of diseases. As natural antioxidants seldom work singly by themselves but as part of a synergistic action of antioxidative systems, further studies are needed.