Hypoglycemic Effect of Calendula arvensis Flowers is Mediated by Digestive Enzyme Inhibition

Background: Calendula arvensis is an annual Mediterranean plant growing in Morocco between Rabat and Khemissat. C. arvensisis is known in folk medicine as an anti-inflammatory and antipyretic remedy. However, few reports have investigated its pharmacological properties. Methods: The objective of the present study was to determine chemical composition of C. arvensis flowers, and to investigate their antidiabetic activities by mean of digestive enzyme inhibition. The profile of phenolic compounds was established by HPLC-DAD-QTOF-MS analysis. While the antidiabetic activity was evaluated by the in vitro enzyme inhibition assays. Results: Phytochemical analysis revealed the presence of anthocyanins, flavonoids, tannins, and saponins as major elements. Whereas, alkaloids and terpenes were not detected in the plant samples. The chromatographic quantification identified 18 metabolites, with the caffeic acid as a major element. C. arvensis aqueous and methanolic extracts exhibited higher inhibitory potential against α-amylase, α- glucosidase and ß-galactosidase compared to the hexanic extract. Conclusion: The present study brings evidence to the hypoglycemic effect of C. arvensis flowers through enzyme inhibitory activities, and identifies the possible phenolic compounds associated with this activity.