Effect of yam (Dioscorea cayenensis) and dasheen (Colocassia esculenta) extracts on the kidney of streptozotocin-induced diabetic rats

Streptozotocin-induced diabetic wistar rats were maintained for 4 weeks on a supplement of extracts of yam (Dioscorea cayenensis) or dasheen (Colocass ia esculenta). The activities of malic enzyme, NADP(+) isocitrate dehydroge nase, Glucose 6-P-dehydrogenase and the transaminases were determined to as sess any degree of metabolic alteration caused by diabetic nephropathy. Dia betic rats fed normal diet and those fed yam extract, dasheen extract and c ommercial linamarin respectively lost weight significantly compared to heal thy controls. The diabetic rats fed dasheen extract, maintained near normog lycaemic values compared to diabetic rats on normal diet (P < 0.05). Malic enzyme activity was significantly reduced (P < 0.05) in diabetic rats on th e normal diet compared to normal healthy controls. Feeding of yam or dashee n extract raised the activity of this enzyme towards normal. Feeding of das heen extract or commercial linamarin significantly lowered (P < 0.05) the a ctivity 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 healt hy controls (P < 0.05). These results demonstrate an overall aggravation of the diabetic nephropathy by yam and dasheen extracts in the diet. In the C aribbean region where these foods are dietary staples, there may be a corre lation with the reported high prevalence of diabetes mellitus and the devel opment of renal disease.