Studies on the antioxidative activities of Hsian-tsao (Mesona procumbens Hemsl) leaf gum.
This study aimed at evaluating the antioxidative activity of crude hsian-tsao leaf gum extracted by sodium bicarbonate solutions and precipitated by 70% ethanol. The antioxidative activities, including the radical-scavenging effects, Fe(2+)-chelating ability, and reducing power as well as the inhibition of FeSO(4)-H(2)O(2)-induced malondialdehyde formation in rat tissue homogenate were studied in vitro. It was found that the antioxidative effect provided by hsian-tsao leaf gum was strongly concentration dependent. In general, the antioxidative activity increased with increasing gum concentration, to a certain extent, and then leveled off with further increase in gum concentration. A concentrtaion-dependent kinetics for the rate of change in antioxidative activity was proposed. The antioxidative activity constant (k) and the half-inhibition concentration (IC(50)) for each antioxidative reaction studied were calculated. From a comparison of the IC(50) values for different antioxidative reactions, it seemed that hsian-tsao leaf gum was more effective in scavenging superoxide radicals than chelating Fe(2+) or scavenging alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radicals. As compared to the commercial antioxidants, hsian-tsao leaf gum showed less scavenging effect on the DPPH radical and reducing power but better superoxide radical-scavenging effect and Fe(2+)-chelating ability than alpha-tocopherol and BHT.
Department of Food and Nutrition, Providence University, 200 Chungchi Road, Shalu, Taichung 433, Taiwan.
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Lai
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Chou
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Chao
D000818:Animals; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D019659:Asteraceae / Q000737:chemistry*; D000431:Ethanol; D016166:Free Radical Scavengers / Q000494:pharmacology; D007501:Iron / Q000737:chemistry; D015227:Lipid Peroxidation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D017693:Sodium Bicarbonate; D013481:Superoxides / Q000378:metabolism
D000975:Antioxidants; D016166:Free Radical Scavengers; D010936:Plant Extracts; D013481:Superoxides; D000431:Ethanol; D008315:Malondialdehyde; D017693:Sodium Bicarbonate; D007501:Iron