Ipomoea hederacea Jacq.: A plant with promising antihypertensive and cardio-protective effects

Abstract

Ethnopharmacological relevance: Seeds of Ipomoea hederacea Jacq. (family: Convolvulaceae) are traditionally used to treat high blood pressure and cardiac diseases.

Aim of the study: Present study was conducted to validate the traditional claim and explore the possible mechanism(s) of antihypertensive effects of I. hederacea.

Materials and methods: Aqueous-ethanolic extract and activity based fractions of I. hederacea were evaluated using invasive blood pressure measuring technique, isolated tissue experiments, fructose induced hypertension/metabolic syndrome and biochemical analysis.Phytochemical analysis of active fraction was performed with aim to identify chemical composition of I. hederacea seeds. LC-MS analysis was also performed to identify the compounds proposed to be present in active fraction of I. hederacea seeds.

Results: Crude extract/fractions of I. hederacea showed dose (0.01-100 mg/kg) dependent significant hypotensive effect in normotensive anesthetized rats, similar to verapamil (0.01-30 mg/kg). Pretreatment with hexamethonium and atropine mediated no significant changes in hypotensive effect of butanol fraction of I. hederacea (Ih.Bn) at 3 mg/kg dose. However, a significant decrease in the hypotensive effect of Ih.Bn 3 mg/kg (-34.82 ± 3.36%; p < 0.05) was observed in the presence of L-NAME (20 mg/kg). Similarly, Ih.Bn (3 mg/kg) showed no significant effect on angiotensin-II response. However, response of phenylephrine (45.60 ± 9.63%; p < 0.05) and dobutamine (18.25 ± 2.10%; p < 0.01) was significantly decreased in the presence of Ih.Bn 3 mg/kg. Ih.Bn also exhibited dose dependent (0.01-100 mg/kg) antihypertensive effect in fructose induced hypertensive rats, similar to verapamil (0.01-30 mg/kg). Concomitant treatment with Ih.Bn (3, 10 and 30 mg/kg) for six weeks showed a dose dependent profound protection with significant (p < 0.01) effect at 30 mg/kg against fructose induced basal mean arterial pressure (142.2 ± 4.62 mmHg). Ih.Bn did not significantly change response of PE, Ang-II and Epi was observed in invasive and ex vivo techniques. However, Ih.Bn significantly (p < 0.01; p < 0.001) prevented against decrease in vascular response of acetylcholine in anesthetized rats and in isolated aorta of rat. A significant dose dependent decrease in triglyceride and glucose level (p < 0.001), and increase in HDL level (p < 0.05) was observed in Ih.Bn treated groups. Results of LC-MS analysis of Ih.Bn showed the presence of 24 compounds that belong to different chemical classes, including carboxylic acid, flavonoids, oligopeptides and tripeptide that are known to have antihypertensive and vasorelaxant properties.

Conclusions: Results of present study indicate the presence of hypotensive/antihypertensive effect in crude extract/fractions of I. hederacea with most potent effect shown by butanol fraction (Ih.Bn), possibly mediated through α₁ blocking, β blocking and iNOS/cGMP stimulating activity.

Keywords: Beta blocking activity; Metabolic syndrome; Nitric oxide synthase; Vascular dysfunction.