Preclinical Vascular Activity of an Aqueous Extract from Flowers of Calendula officinalis

Various parts of Calendula officinalis have been used as a medicinal herb. This study was carried out to evaluate the effects of an aqueous extract from flowers of Calendula officinalis on vascular smooth muscle of rats. The effects on aortic contraction of the extract of C. officinalis at different concentrations were assessed in endothelium-denuded rat thoracic aortic rings pre-contracted with 60 mmol/L of KCl. The results demonstrated that the extract induced a concentration-dependent relaxation in endothelium-denuded rat aortic rings with an IC50 of 0.5 ± 0.01 mg/mL. In conclusion, this investigation has shown that the mode of action on the vasorelaxant effect caused by this extract is endothelium-independent. The findings from this study provide a scientific basis for the use of this plant in traditional medicine and merits further investigations.