Research:
Antioxidant and Cellular Protective Properties of Astragalus
Astragalus constituents, particularly the flavonoids, exert significant cellular antioxidant effects that appear to be protective against cardiovascular, hepatic, pulmonary, and renal pathological changes.54,55 In vitro, astragalus has been reported to protect against free radical-mediated renal tubular damage induced by high-energy shock waves56 and against radiation injury23. In the hearts of healthy animals and animal models of cardiovascular disease, astragalus polysaccharide and flavonoid fractions have been reported to scavenge mitochondrial free radicals, protect against lipid peroxidation, protect mitochondria from isoproterenol-induced injury, prevent diabetes-induced myocardial hypertrophy, and attenuate pathophysiological decrements in cardiac structure and function in congestive heart failure, diabetes, and experimental hypertension.57,58,59,11,60,61 Astragalus polysaccharide and flavonoid extracts have been shown to preserve kidney function in animal models of renal failure and liver functions in response to hepatotoxins.56,62,63,4,64,65,66 Similarly, astragalus appears to protect cells against hypoxic challenges. Astragaloside IV has been reported to protect human endothelial cells and intestinal epithelial cells against reperfusion injury in vitro following hemorrhagic shock.67 Cellular protection from anoxia has also been observed in cultured neurons68 and in mouse brains after transient focal ischemia69. Astragaloside IV has also inhibited platelet aggregation, decreased plasminogen activation, and facilitated intravascular lysis of fibrin clots in humans and in animal disease models.18,70 In a model of ototoxicity, Xuan et al. reported that astragalus protected cells from pathologic injury via enhanced DNA and RNA synthesis.65 In an animal study, Astragalus membranaceus had preventive and therapeutic potential in experimental colitis.1 The anti-inflammatory actions involved antioxidation along with the inhibition of adhesion molecule synthesis in the colonic tissues. In an in vitro study, astragalus and astragalus saponins potently protected endothelium-dependent relaxation against the acute injury from homocysteine through nitric oxide regulatory pathways, in which antioxidation played a key role.31
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