In vitro antioxidant properties and total phenolic contents of wetland medicinal plants in Taiwan

The aim of this study was to examine the possible antioxidant activities of the methanol and water extracts of 31 medicinal wetland plants in Taiwan. We assayed for such properties such as: TEAC, DPPH radical scavenging, total polyphenol content, total flavonoid and total flavonol contents using the reducing power method. Our results showed that Rotala rotundifolia, Juncus effusus var. decipiens, Cyperus inn, Salix warburgii, Lindernia antipoda, Kyllinga brevifolia, and Typha orientalis possessed both high antioxidant activities and high total polyphenol contents. There was a low correlation between TEAC and total polyphenol content (water extracts, R-2=0.14; methanol extracts, R-2=0.23) thus eliminating high phenolic content as an important factor in determining the wetland plants' antioxidant capacities. Our results demonstrated that although phytochemicals in the wetland medicinal plants may contribute significantly to their antioxidant activities, these antioxidant activities were not directly related to the polyphenol quantity. Phytochemicals may play key roles in the potent antioxidant activity of wetland medicinal plants. The potential of these easily accessible sources of natural antioxidants should be explored by the pharmaceutical, medical, and health food industries.