Nigella Sativa AQUEOUS AND HYDRO-METHANOL EXTRACTS ACT AS A NOVEL BLOCKER FOR ANGIOTENSIN II RECEPTOR TYPE I

Abstract

Background: It is well known that Nigella sativa seeds have been widely used in folk medicine for the treatment of cardiovascular diseases. Little is known, however, about their effect on angiotensin II receptor type I. Studying of such impact will be valuable in producing herbal medicines with much less side effects compared to conventional drugs. Objective: The aim of the current research was to study the blocking effect of hydromethanolic (NS.HM) and aqueous (NS.Aq) extracts of Nigella sativa on angiotensin II (Ang II) receptor type I (AT1) in isolated rat's aorta. Materials and Methods: Seed's powder was soaked in 50% hydromethanol and distilled water separately for 48 hrs, then filtered through Whatman filter papers. The solvents were evaporated to yield the crude extracts (NS.HM and NS.Aq). The effect of different concentrations (1, 2, 3 & 4 mg/ml) of NS.HM and NS.Aq extracts on isolated rat's aorta contracted with various doses of Ang II (0.3, 1.0, 3.0, 10, 30 & 100 µM) were evaluated. Results: NS.HM at concentrations 3 and 4 mg/ml, caused a very high significant (P< 0.001) inhibitory effect on the dose-response curves (DRCs) in aortic rings at doses 3 and 10 µM of Ang II as compared to the control, and a highly significant (P< 0.01) inhibition at doses one µM (for 3 mg/ml), and 1 and 30 µM (for 4 mg/ml). Furthermore, NS.HM at concentrations 1 and 2 mg/ml did not produce any significant right shifting. On the other hand, NS.Aq extract at concentration 4 mg/ml caused a very high significant (P< 0.001) right shifting DRC at doses 3 and 10 µM, and highly significant (P< 0.01) shifting at 30 µM of Ang II. Besides, significant right shifting (P< 0.05) was observed in the DRC in the presence of the extract at dose one µM as compared to the control. Nevertheless, no right shifting in the DRC of Ang II at concentrations 1, 2, and 3 mg/ml of NS.Aq was noticed. Conclusions: We conclude that Both NS.HM and NS.Aq extracts have an anti-hypertensive effect through blocking the AT1 receptors, although NS.HM extract is more potent in blocking effect on AT1R than NS.Aq. In addition, the anti-hypertensive effect of both NS.HM and NS.Aq extracts on the aorta are concentration-dependent.