Controversial effects of Calendula officinalis L. on Biochemical and Pathological Factors of Nephropathy in Diabetic Wistar Rats

Chronic hyperglycemia leads to microvascular and macrovascular complications such as diabetic nephropathy. Medicinal plants are good sources for finding new therapeutic chemicals to improve diabetes and relieve its symptoms. The purpose of the present study was to evaluate the effect of the hydroalcoholic extract (300 mg/kg) of Calendula officinalis (marigold) on blood biochemical profiles and histopathological changes in kidney of streptozotocin-induced diabetic rats. Twenty male Wistar rats were divided to four groups: Normal control (NC), diabetic control (DC), normal C. officinalis (N+CO) 300 mg/kg, and diabetic C. officinalis (D+CO) 300 mg/kg. The rats were treated for a period of 13 weeks. Diabetes was induced by Streptozocin injection, intraperitoneally. Level of glucose, urea, creatinine and also total anti-oxidant capacity, malondialdehyde, total oxidant status in serum and histological alterations in the kidney were analyzed. Level of serum glucose, urea, creatinine, malondialdehyde and total oxidant status were increased in diabetic rats, whereas, total anti-oxidant capacity was decreased compared to the control animals. Also, histological findings confirmed the absence of integrity in glomerulus and mass infiltration in kidney tissue in diabetic rats compared to the normal controls. Calendula officinalis extract had no effect on blood glucose, but it decreased blood urea nitrogen and creatinine, total oxidant status and malondialdehyde while it increased total anti-oxidant capacity in the diabetic extract-treated group when compared to diabetic rats. Calendula officinalis could not prevent nephropathy changes in the diabetic rats. Therefore, our results suggest that although administration of 300 mg/kg of Calendula officinalis extract showed salutary effects on anti-oxidant profile, yet its protective effects on anti-diabetic and regenerative properties on nephropathy were ambiguous and require more investigations.