The polyphenol fraction of Actinidia arguta (AP) inhibited α-glucosidase activity in vitro. The oral administration of AP with maltose and starch suppressed postprandial hyperglycemia associated with the intake of the respective sugars by rats. The area under the curve (AUC) of blood glucose in the oral glucose tolerance test (OGTT) of type 2 diabetic KK-A y mice, fed AP for 6 weeks, significantly decreased when compared with that of the control group. The fraction containing isoquercitrin and hyperoside, which was prepared from AP, showed a stronger inhibitory activity for maltase. The blood glucose levels in OGTT of KK-A y mice fed isoquercitrin for 4 weeks tended to be lower at 60 min after the administration of glucose.These results suggested that AP has antidiabetic effects, and isoquercitrin, a component of AP, may be useful in preventing type 2 diabetes mellitus. A decrease in the G6Pase activity and increase in the ACO or CPT activities in the liver of KK-A y mice fed AP or isoquercitrin suggested that the suppression of gluconeogenesis and the enhancement of β-oxidation of lipids, as well as the inhibition of maltase by AP and isoquercitrin, might also be related to their anti-diabetic effects.

This study investigates the anti-fatigue effects of Acanthopanax sieboldianus (A. sieboldianus) at various exercise intensities. Two experiments were conducted in 18 Sprague-Dawley rats. In Experiment 1, a three-stage increment test (15 m/min for 5 min, and 20 m/min for 5 min and 25 m/min for 10 min) was performed using a treadmill. In Experiment 2, a 10-min swimming test was conducted. Blood samples were extracted from each rat before, during and after the exercises and the blood concentrations of lactate and glucose measured. In both experiments, water (control) or A. sieboldianus solution (ASS) was administered orally using a zonde 30 min before the exercise. In the swimming test, ASS administration significantly decreased the blood lactate level measured at the end of the exercise and 5 min post-exercise relative to the water group, although the two groups did not differ significantly in the treadmill test. Our study demonstrates that a single oral administration of A. sieboldianus prior to high-intensity exercise significantly decreases the blood lactate concentration suggesting that A. sieboldianus has an intrinsic anti-fatigue effect.

The feeding of unripe persimmon (PP) ('Hiratanenashi', pollination variant) and soluble tannin (PST), as its component, on blood pressure was examined in spontaneously hypertensive rats (SHR). Systolic blood pressure (SBP) was decreased by PP and PST administration for 2-3 days and increased after switching to the basal diet alone. Increases in serum nitric oxide level and liver NOS3 gene expression in SHR fed PP suggests that the induction of nitric oxide formation by PP administration might be involved in decreasing SBP. The decrease in ACE activity by PST administration suggests that, as a component of PP, PST mainly lowers SBP through its angiotensin I-converting enzyme (ACE) inhibitory effect. Scopoletin, contained as a minor component in PP and PST, decreased SBP by single oral administration, suggesting that it also might be involved in lowering SBP.

A compound with +,+-diphenyl-,-picrylhydrazyl (DPPH) radical scavenging activity, produced in the course of roasting co#ee beans, was isolated from instant co#ee. The chemical structure of this compound was elucidated to be --pyridinol on the basis of various spectra analyses. It prevented cytotoxicity induced by D-galactosamine in primary cultured rat hepatocytes, indicating that this compound may prevent liver injury partly induced by the action of radicals.