Effects of Dietary Fiber Extracted from Ipomoea aquatica on Blood Glucose Levels of Rats Following Glucose Challenge

Ipomoea aquatica Forsk., exerts significant oral hypoglycemic activity in normal and diabetic Wistar rats and type II diabetic patients [1]. The soluble and insoluble dietary fibers isolated from I. aquatica, were tested along with the whole extract for any hypoglycemic effect on rats. Isolation of soluble and insoluble dietary fiber was carried out by modifying, the method of Asp et al. without the incineration step [2]. Four groups of rats were termed whole extract (WE), soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and control with 8 rats in each. After an overnight fast the WE group was given the whole extract (1ml). To the SDF and IDF groups, suspensions of soluble and insoluble dietary fiber were given (1ml each). Distilled water was administered to the control. Rats were subjected to glucose challenge and serum glucose was determined. The mean serum glucose concentration of the rats treated with the WE, SDF, IDF and distilled water were 3.5±0.08, 5.1±0.1, 5.4±0.1 and 6.3±0.1µmol/L. Reductions in serum glucose levels of WE (p=0.0000005), SDF (p=0.000792), IDF (p=0.00154) groups were significantly higher than the control. There was a 45.3% reduction with the whole extract compared with control; (19.0% and 13.0% reductions in the SDF and IDF treated groups; ANOVA F=73.835 and p=2.06 E-13). The hypoglycemic effect exerted by the whole extract was significantly higher than the effect of soluble and insoluble dietary fiber extracted from I. aquatica. The results confirmed the presence of an active compound other than dietary fiber. Acknowledgements: Financial assistance by University of Sri Jayewardenepura is gratefully acknowledged. References: [1] Asp NG, Johansson CG, et al. (1983)J. Agric. Food Chem. 31: 476–482. [2] Malalavidhane TS, Wickramasinghe SMDN, et al (2003) Phytother Res. 7(9): 1098–100.