Cardioprotective effect of hydroalcoholic extract stem bark of Xeroderris stuhlmannii on cadmium chloride-induced hypertension and its possible vasorelaxant mechanism on isolated aortic rats

Abstract Background Xeroderris stuhlmannii is a medicinal plant, widely used in Cameroonian folk medicine to treat hypertension. Objective This study aimed to investigate the beneficial effect of X. stuhlmannii in hypertensive rats and to explore the vasorelaxant mechanisms of its hydroalcoholic extract and to determine the compounds responsible of the activities. Materials and methods Hydroalcoholic extract, fractions, subfractions and isolated compounds were screened for the antihypertensive activity in Wistar rat of either sex using a noninvasive method to record blood pressure (BP) and heart rate (HR). At the end of the treatment, the level of nitrite in the tissues and the histological analysis of the heart and aorta were determined. Vasorelaxant activity of the plant was carried out in vitro, on the contractile responses of aortic rings induced by phenylephrine (10−6 M) or KCl (60 mM). Mechanisms involved vasorelaxation effect of X. stuhlmannii were assessed using various antagonists. Results Treatment of Cadmium-hypertensive rats with extract significantly (p ˂ 0.001) reduced BP and HR, improved nitrite level, ameliorated heart and aorta alterations. Moreover, the hydroalcoholic extract, fractions, subfraction and odoratin-induced vasorelaxant effect. The preincubation with NG-nitro-L-arginine methyl ester, methylene blue and tetraethylammonium partially inhibited hydroalcoholic extract/fraction-induced relaxation. The extract completely inhibited the effects on CaCl2-induced contracted rings and reduced the contraction induced by phenylephrine in a Ca2+-free solution. Conclusion These results support the traditional use of X. stuhlmannii in the treatment of hypertension. This effect may be due in part to the plant’s vasorelaxant activity and the presence of compounds such as phenol in plant extracts.