Antihypertensive and vasodilator effects of methanolic extract of Inula viscosa: Biological evaluation and POM analysis of cynarin, chlorogenic acid as potential hypertensive.

Background: Inula viscosa L. (Asteraceae) is a medicinal plant widely used as a folk medicine in oriental Morocco, to treat hypertension. The antihypertensive effect of the methanolic extract obtained from I. viscosa leaves was evaluated in hypertensive L-NAME rats. Systolic blood pressure (SBP) was measured using a non-invasive indirect tail-cuff plethysmographic method. Four groups of rats were used: a control group; a hypertensive group treated with L-NAME (32mg/kg/day); a positive control group treated with L-NAME plus enalapril (15mg/kg/day) as a reference antihypertensive agent; and a group treated with L-NAME plus MeOH-extract (40mg/kg/day).

Methods: Treatment with L-NAME alone caused a progressive increase in SBP. After 4 weeks, the value of SBP reached 160±2mmHg which shows the installation of hypertension. Enalapril prevented the increase in SBP, which remained normal at 123±1mmHg after 4 weeks of treatment. The administration of MeOH-extract along with L-NAME prevented the increase in SBP as well, which remained constant at 115±1mmHg after 4 weeks of treatment. In ex-vivo models, MeOH-extract produced a relaxation of pre-contracted ring aorta (54 ± 2% of relaxation at 3g/L). But, when the rings were denuded, MeOH-extract failed to relax pre-contracted rings of aorta. Phytochemical study of I. viscosa MeOH-extract revealed the presence of phenolic compounds, such as cynarin and chlorogenic acid.

Results: The present results suggest that I. viscosa MeOH-extract has an antihypertensive, predominantly mediated by an endothelium-dependent vasodilatory effect. Cynarin and chlorogenic acid, which have a strong vasorelaxant effect may be involved in the antihypertensive effect of the plant extract. The bioinformatic POM analysis confirms the therapeutic potential of cynarin and chlorogenic acids as inhibitors of various biotargets. Based on the results, the coordination of these phytochemicals with calcium and transition metals should be studied, for better scope at antihypertensive drug development.