Effects of an aqueous extract of Salacia reticulata, a useful plant in Sri Lanka, on postprandial hyperglycemia in rats and humans
1998
Shimoda. H. (Morishita Jintan Co. Ltd., Osaka (Japan)) | Kawamori, S. | Kawahara, Y.
Salacia reticulata is a plant commonly used in Sri Lanka for the prevention of hyperglycemia. The ihibitory effects of an aqueous extract from the stem of Salacia reticulata Wight (SRE) (Celastraceae) on postprandial hyperglycemia in rats and humans were investigated. SRE dose-dependently suppressed elevation of the serum glucose level induced by sucrose, maltose and a-starch, but not by glucose or lactose. The suppressive effect of SRE was more potent against sucrose-induced hyperglycemia than against hyperglycemia induced by the other sugars. In addition, we investigated the effects of SRE on activities of various glucosidases and alpha-amylase. The results showed that SRE strongly inhibited the activities of alpha-glucosidases prepared from yeast and rat jejunum (IC50: 5 and 8 mug/mL respectively). SRE also inhibited the activity of alpha-amylase (IC50: 35 mug/mL), but not that of beta-glucosidase. The relative inhibitory effects of SRE against partially purified alpha-glucosidases from rat jejunum showed the order: sucrase = isomaltase (IC5O: l5 mug/mL respectively) maltase (IC50: 70 mug/mL). Moreover, in a sucrose tolerance test performed on human volunteers, 5 min pretreatment with SRE (200 mg) prior to sucrose (50 g) loading significantly suppressed postprandial hyperglycemia. These results demonstrate that, based on its inhibition of alpha-glucosidases and alpha-amylase, SRE has anti-hyperglycemic activity, and may be a useful natural material for the preventi
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