| Summary: | 碩士 === 國立中興大學 === 農藝學系 === 90 === Reactive oxygen free radical species (ROS) are highly reactive and potentially damaging transient chemical species formed in all cells. Cells are protected from ROS induced damage by a variety of endogenous ROS scavenging enzymes and chemical compounds. Recently there has been upsurge of interest in the therapeutic potential of medicinal plants as antioxidants in reducing such free radical induced tissue injury. In this regard, while the Hypericum perforatum, H. sampsonii, H. japonicum have long been used in herbal medicine for the treatment of burns, bruises, swelling, anxiety, antiaepressant, antinflammatory and antiseptic property, relatively little information is available concerning the antioxidant potential of these plant species. The objective of the present work was, therefore, to carry out a systematic survey of the relative levels of antioxidant potential in those selected medicinal plant species used in traditional or modern medical practice.
The results showed that all antioxidant properties including total thiol, glutathione, ascorbate, phenolic and hypericin content, the activities of superoxide dismutase, peroxidase, glutathione peroxidase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase were significantly difference among three selected medicinal plant species. The activity of superoxide dismutase was much higher than the others. Although the total antioxidant level and hypericin content in oven-dry material were higher than fresh tissue and lyophilized materials, but the antioxidant enzyme activities and total antioxidant capacity measured by the AAPH radical scavenging method were much lower than the others. Comparison the effects of extract solvent and extract methods indicated that acetone was a better solvent in the extraction of hypericin than water, and grinding extract was more efficiency to extract antioxidant substances which contributed the antioxidant capacity than infusion.
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