To study the extracts of yam (Dioscorea cayenensis) or dasheen (Colocassia esculenta) on streptozotocin-induced diabetic wistar rats

Streptozotocin-induced diabetic wistar rats were maintained for 4 weeks on a supplement of extracts of yam (Dioscorea cayenensis) or dasheen (Colocassia esculenta). The activities of malic enzyme, NADP+ isocitrate dehydrogenase, Glucose 6-P-dehydrogenase and the transaminases were determined to assess any degree of metabolic alteration caused by diabetic nephropathy. Diabetic rats fed normal diet and those fed yam extract, dasheen extract and commercial linamarin respectively lost weight significantly compared to healthy controls. The diabetic rats fed dasheen extract, maintained near normoglycaemic values compared to diabetic rats on normal diet (P < 0.05). Malic enzyme activity was significantly reduced (P < 0.05) in diabetic rats on the normal diet compared to normal healthy controls. Feeding of yam or dasheen extract raised the activity of this enzyme towards normal. Feeding of dasheen extract or commercial linamarin significantly lowered (P < 0.05) the activity of NADP+ isocitrate dehydrogenase below that of healthy controls. Glucose 6-P-dehydrogenase activity was significantly increased (P < 0.05) in diabetic rats compared to healthy controls. Alanine transaminase in the kidney of diabetic rats fed yam extract was significantly higher than healthy controls (P < 0.05). These results demonstrate an overall aggravation of the diabetic nephropathy by yam and dasheen extracts in the diet. In the Caribbean region where these foods are dietary staples, there may be a correlation with the reported high prevalence of diabetes mellitus and the development of renal disease.