We evaluated antihyperglycemic and anti-obese effects of Panax ginseng berry extract and its major constituent, ginsenoside Re, in obese diabetic C57BL/6J ob/ ob mice and their lean littermates. Animals received daily intraperitoneal injections of Panax ginseng berry extract for 12 days. On day 12, 150 mg/kg extract-treated ob/ob mice became normoglycemic (137 +/- 6.7 mg/dl) and had significantly improved glucose tolerance. The overall glucose excursion during the 2-h intraperitoneal glucose tolerance test decreased by 46% (P < 0.01) compared with vehicle-treated ob/ob mice. The improvement in blood glucose levels in the extract-treated ob/ ob mice was associated with a significant reduction in serum insulin levels in fed and fasting mice. A hyperinsulinemic-euglycemic clamp study revealed a more than twofold increase in the rate of insulin-stimulated glucose disposal in treated ob/ ob mice (112 +/- 19.1 vs. 52 +/- 11.8 micromol x kg(-1) x min(-1) for the vehicle group, P < 0.01). In addition, the extract-treated ob/ob mice lost a significant amount of weight (from 51.7 +/- 1.9 g on day 0 to 45.7 +/- 1.2 on day 12, P < 0.01 vs. vehicle-treated ob/ob mice), associated with a significant reduction in food intake (P < 0.05) and a very significant increase in energy expenditure (P < 0.01) and body temperature (P < 0.01). Treatment with the extract also significantly reduced plasma cholesterol levels in ob/ob mice. Additional studies demonstrated that ginsenoside Re plays a significant role in antihyperglycemic action. This antidiabetic effect of ginsenoside Re was not associated with body weight changes, suggesting that other constituents in the extract have distinct pharmacological mechanisms on energy metabolism.

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Flavonoids within Scutellaria baicalensis may be potent antioxidants on the basis of our studies of S. baicalensis extract. To further this work, we studied the antioxidative effects of baicalein, a flavonoid component of S. baicalensis, in a chick cardiomyocyte model of reactive oxygen species (ROS) generation during hypoxia, simulated ischemia-reperfusion, or mitochondrial complex III inhibition with antimycin A. Oxidant stress was measured by oxidation of the intracellular probes 2Ј,7Ј-dichlorofluorescin diacetate and dihydroethidium. Viability was assessed by propidium iodide uptake. Baicalein attenuated oxidant stress during all conditions studied and acted within minutes of treatment. For example, baicalein given only at reperfusion dose dependently attenuated the ROS burst at 5 min after 1 h of simulated ischemia. It also decreased subsequent cell death at 3 h of reperfusion from 52.3 Ϯ 2.5% in untreated cells to 29.4 Ϯ 3.0% (with return of contractions; P Ͻ 0.001). In vitro studies using electron paramagnetic resonance spectroscopy with the spin trap 5-methoxycarbonyl-5-methyl-1-pyrroline-N-oxide revealed that baicalein scavenges superoxide but does not mimic the effects of superoxide dismutase. We conclude that baicalein can scavenge ROS generation in cardiomyocytes and that it protects against cell death in an ischemia-reperfusion model when given only at reperfusion.

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