Effects of Hydroalcoholic Flower Extract of Marigold (Calendula officinalis) on the Biochemical and Histological Parameters in STZ-Induced Diabetic Rats

Background: Calendula officinalis, an aromatic plant and rich of various chemical compounds, has been widely used in folk medicine for the treatment of different diseases. Objectives: We investigated the effects of hydroalcoholic flower extract of Calendula officinalis on the biochemical and histological parameters in STZ-induced diabetic rats. Methods: Thirty-six male Wistar rats were divided into four groups: healthy control, diabetic control, diabetic treated with 250 and 500 mg/kg of the hydro-alcoholic extract, respectively. The biochemical and histological measurements were assessed by standard methods. Results: The oral administration of the hydroalcoholic extract of marigold flower resulted in a recovery of body weight and significantly decreased fasting blood sugar (FBS) (P < 0.05). Alanine aminotransferase (ALT), albumin and total bilirubin concentration were significantly recovered after treatment with the extract (P < 0.05). Measurement of homeostasis model assessment for beta-cell function (HOMA-beta) indicated that the reduction of serum insulin concentration after treatment with the extract may be due to the recovery of beta cell function. Moreover, the extract induced insulin secretion from the rat's isolated pancreatic islets under a glucose-stimulated condition in a dose-dependent manner. The STZ-induced complications on the pancreas, kidneys, and liver were improved after treatment with the extract. Conclusions: Our findings suggest that the potential protective effects of marigold flower extract against the diabetic-induced complicationsmaybe mediated by its effect on the reduction of blood glucose and its direct effect on the glucose-stimulated insulin secretion.