Antidiabetic and antioxidant activities of phenolic extracts of Conyza dioscoridis (L.) shoots

Objectives : Diabetes mellitus has become one of the most prevalent diseases in many countries. Medicinal plants are recurrently the most promising sources of safe drugs for several diseases. Our study aimed to finding of antidiabetic active extracts from the shoots of Conyza dioscoridis along with investigation of the bioactive constituents and antioxidant activity. Methods : The bioactive constituents were isolated and identified by chromatographic and spectroscopic techniques. Antioxidant activity was evaluated by DPPH radical-scavenging method. Antidiabetic activity was evaluated using biochemical and histopathological parameters. Results : Four flavonoids, kampferol, quercetin, quercetin 3- O -β-D-glucopyranoside, quercetin 3- O -α-L–rhamnopyrano­syl-(1→6)-β-D- glucopyranoside, and two phenolic acids, caffiec acid and chlorogenic acid, were isolated. Fifty compounds were identified by GC/MS in the essential oil obtained by hydro-distillation of the plant, in which sesquiterpenes represented the main constituents. Ethyl acetate, methanol extracts and the herb revealed significant antioxidant activity. The extracts did not produce any obvious toxic symptoms or mortality. Significant increase and reduction of glucose and insulin were recorded, respectively in the diabetic group, while treatment of extracts restored these parameters. The histopathological studies of the diabetic rats indicated increase in the volume density of islets, percent of β cells and size of islets in the groups that received EtOAc and methanol extracts, which suggested regeneration of β cells repairs, as compared with the diabetic group. Conclusion : The net results confirmed that this plant is a promising plant with bioactive constituents. This herbal therapy appears to bring about regeneration of the endocrine pancreas cells protection in the diabetic rat.