Banaba (Lagerstroemia speciosa L.) has been recognized as a folk medicine for diabetes in the Philippines. A hot water extract (HWE) of banaba leaves dose-dependently suppressed the elevation of blood glucose after oral administration of starch, but had no such effect after ingestion of glucose. The HWE was fractionated using HP-20 column chromatography, and its methanol fraction (HPME) was found to suppress the elevation of blood glucose after oral administration of starch. The inhibitory action of the HWE on activities of α-amylase and α-glucosidases was then examined in vitro. The HWE inhibited the activities of α-amylase, maltase, glucoamylase, sucrase and isomaltase, with estimated IC₅₀ values of 0.53, 0.89, 1.24, 2.85 and 4.95mg/mL, respectively. The HPME also inhibited α-amylase and glucoamylase with IC₅₀ values of 0.44 and 0.83mg/mL, respectively. These results suggest that the inhibitory effect of banaba on postprandial hyperglycemia is due to inhibition of α-amylase and α-glucosidases. Banaba may be a useful natural material for the prevention and therapy of diabetes.

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The effects of guar gum alone, or mixed with xanthan gum, on plasma and liver lipids were studied in rats fed high-sucrose diets. Rats were fed a high-starch diet (control diet), a high-sucrose diet (HS diet), or a HS diet supplemented with guar gum (HS-G diet) or a mixture of guar gum and xanthan gum (2:1, w/w, HS-GX diet) at 3% for 4 weeks. The plasma levels of glucose and insulin were not altered by intake of the HS, HS-G, or HS-GX diet. The plasma total cholesterol and plasma and liver triacylglycerol levels were elevated in rats fed the HS diet compared to rats fed the control diet, and were lowered to the control level in rats fed the HS-G or HS-GX diet. The HS-GX diet had a significantly more marked effect than the HS-G diet. Bile acids and lipids excreted in feces were increased in rats fed the HS-G or HS-GX diet, and the effects of the latter diet were significantly higher than those of the former. Fatty acid synthase activity in the liver, which was increased in rats fed the HS diet, was lowered in rats fed the HS-GX diet. The mechanism responsible for the cholesterol-lowering effect of the HS-GX diet was partly related to enhanced excretion of bile acids into feces, while that responsible for the hypotriacylglycerolemic effect was related to the decreased absorption of dietary lipids and decreased activity of fatty acid synthase in the liver.

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The effects of chloride on stroke incidence and blood pressure were examined in salt-sensitive hypertensive rats. Stroke-prone spontaneously hypertensive rats (SHRSP) and Dahl salt-sensitive (DahlS) rats were fed on a 3% NaCl diet with or without 5% chitosan or 5% alginate, which have potent inhibitory effects on intestinal absorption of chloride and sodium, respectively. In SHRSP, the chitosan diet prevented stroke efficiently, whereas the alginate diet had no significant preventive effect. In DahlS rats, although the chitosan diet attenuated salt-accelerated hypertension, the alginate diet had no effect on blood pressure. In DahlS rats, 1h of feeding on the high-salt diet increased the serum chloride concentration and stimulated the activity of angiotensin converting enzyme (ACE), whereas no changes were seen in the group given the high-salt diet with chitosan. These results suggest that chloride induces stroke and hypertension in salt-sensitive hypertensive rats, concomitant with stimulation of serum ACE activity.

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The durations of α-glucosidase inhibitory activity of various sugars administered to unrestrained, unanesthetized rats via portal cannulae were examined. The measured duration were the times for which elevation of portal glucose levels resulting from continuous intragastric infusion of maltose or sucrose were suppressed by the sugars. D-Xylose (0.24g/kg), L-arabinose (0.24g/kg) and D-glucurono-6, 3-lactone (0.24g/kg), as well as acarbose (0.024g/kg) and voglibose (0.00024g/kg), α-glucosidase inhibitors, suppressed the elevation of portal glucose levels. The durations of the inhibitory effects of D-xylose, L-arabinose, D-glucurono-6, 3-lactone, acarbose and voglibose were 150min, 60min, 90min, 120min and >170min, respectively. These findings indicate the importance of measuring the duration of the inhibitory effect on α-glucosidase when studying α-glucosidase inhibitors.

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A new enteral nutritional formula containing whey protein hydrolysate (WPH) was evaluated for its suppressive effect on indomethacin-induced ulcers. In the first experiment, fewer intestinal ulcers appeared (1/7) in male Sprague-Dawley rats that has received subcutaneous indomethacin administration during the WPH formula feeding period than in those fed formulas containing amino acids (4/6) and intact protein (6/7) as nitrogen sources. In the second experiment, rats were cross-fed on different formulas, and fewer intestinal ulcers appeared in those pre-fed with WPH formula (1/7 in pre WPH- post WPH, 1/8 in WPH-ED, 6/7 in ED-WPH, 5/7 in ED-ED). Similar results were also obtained for cecal ulcers. These results suggest that the WPH formula has a suppressive effect on indomethacin-induced ulcers.

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The effect of oral administration of Kurozu moromi powder on a mouse IgE-mediated dermatitis model was examined. Both immediate type and delayed type responses elicited by the IgE-antigen treatment were significantly and dose-dependently suppressed in mice treated with the Kurozu moromi powder. Thus, it would be of great interest to examine the effect of Kurozu moromi powder on human atopic dermatitis.

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