Author: Nwajiobi Ogonna Joachin
Department: Applied Biochemistry
Affiliation: Nnamdi Azikiwe University Awka
The use of local plants for the management of chronic diseases has increased in the recent past and the dietary management of diabetes mellitus is being encouraged. Two neglected plants in South-Eastern Nigeria, Dioscorea dumetorum (Kunth) Pax (Dioscoreace) and Vigna subterranea Thouars (Fabacea) were evaluated for their nutritional composition and antidiabetic potentials. The tubers and seeds of the plants were used for the studies. Standard procedures of AOAC were used to determine the proximate composition. Atomic Absorption Spectrophotometer was used to determine the mineral composition while Technicon amino acid analyser was used to detect and quantify the amino acids. Alloxan was induced intraperitoneally at the dose of 140 mg kg-1 body weight. Twenty-five animals that became diabetic were grouped into five: D.dumetorumfed, V.subterranea-fed, D.dumetorum + V.subterranea-fed, glibenclamide-administered and standard pellet-fed diabetic rats while a separate group served as a non-diabetic control making up the six groups of thirty wistar albino rats used for the studies. The blood glucose concentration was monitored daily for six days from the day the rats were confirmed diabetic. The rats were sacrificed on the sixth day and biochemical analyses were carried out to determine the lipid profile of the rats. The proximate analysis of D. dumteorum tuber and V. subterranea seed revealed that the values of moisture, ash, crude protein, crude lipid, crude fibre and carbohydrate to be 15%, 3.7%, 8%, 1%, 32%, 40% and 8%, 2.18%, 16.08%, 13.8%, 7.94%, 52% respectively. Mineral analysis in ppm (DW) indicated that the tuber of D. dumetorum contained Na(1.67), K(37.90), Mg(21.50), Ca(59.69), P(4.45), Pb(0.35), Zn(1.38), Fe (28.09), Cu (0.175),Se (12.47) and seed of V. subterranea Na(0.790), K(20.45), Mg(21.55), Ca(43.96), P(4.45), Pb(0.79), Zn(1.28), Fe(2.51), Cu(0.84) and Se(0.21). D. dumetorum had higher (p<0.05) minerals content than V. subterranea. Seventeen amino acids excluding tryptophan, glutamine and asparagine were detected and quantified. Forty-three (43)% and 39% of the amino acids determined in D.dumetorum and V. subterranea respectively were essential. V. subterranea had higher (p<0.05) amino acids content than D. dumetorum. Alloxan increased the blood glucose concentration by an average of 425%. D.dumetorum reduced the blood glucose concentration by 74%, V.subterranea by 72%, D.dumetorum + V.subterranea by 75% while glibenclamide reduced it by 52%. The concentration of triglycerides and Very Low Density Lipoprotein (VLDL) was significantly (p<0.005) lower in the two plants’-fed rats than in the diabetic control. There was no significant difference in the concentration of total cholesterol, High Density Lipoprotein (HDL) and Low Density Lipoprotein (LDL) between the treatment groups and diabetic control. These studies revealed that D. dumetorum tuber and V. subterranea seed are rich in nutritional constituents and possess antidiabetic effect. Combination of both plants may increase their nutritional quality as the plants complement each other in their nutritional composition.
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