Blood pressure lowering effect and vascular activity of Phyllanthus niruri extract: The role of NO/cGMP signaling pathway and β-adrenoceptor mediated relaxation of isolated aortic rings. (25th March 2020)

• Record Type: Journal Article
• Authors: Bello, Idris; Usman, Nasiba Salisu; Dewa, Aidiahmad; Abubakar, Kabiru; Aminu, Nafiu; Asmawi, Mohd Zaini; Mahmud, Roziahanim
• Is Part Of: Journal of ethnopharmacology. Volume 250(2020)
• Publication Date: 2020-03-25
• Subjects: Phyllanthus niruri -- Hypertension -- Antihypertensive -- Isolated aorta rings -- Vasorelaxation -- GC-MS; Ethnopharmacology -- Periodicals; Pharmacognosy -- Periodicals; Herbs -- Periodicals; Herbs -- Periodicals; Pharmacognosy -- Periodicals; Pharmacognosie -- Périodiques; Herbes -- Périodiques; 615.1
• DOI: 10.1016/j.jep.2019.112461
• Languages: English
• ISSNs: 0378-8741

Abstract

Abstract: Ethnopharmacological relevance: Phyllanthus niruri have a long history of use in the traditional treatment of various ailments including hypertension. Literature reports have indicated that it is a potent antihypertensive herbal medication used traditionally. Aim of the study: This study was carried out to investigate the antihypertensive and vasodilatory activity of four solvents extracts of P. niruri namely; petroleum ether (PEPN), chloroform (CLPN), methanol (MEPN) and water (WEPN), with the aim of elucidating the mechanism of action and identifying the phytochemical constituents. Materials and methods: Male Spontaneous Hypertensive Rats (SHRs) were given oral gavage of P. niruri extract daily for two weeks and the blood pressure was recorded in vivo . We also determine the vasodilation effect of the extracts on rings of isolated thoracic aorta pre-contracted with phenylephrine (PE, 1 μM). Endothelium-intact or endothelium-denuded aorta rings were pre-incubated with various antagonists like 1H-[1, 2, 4] oxadiazolo-[4, 3-a]quinoxalin-1-one (ODQ, 10 μM) and Methylene blue (MB 10 μM), sGC inhibitors; Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 10 μM) a nitric oxide synthase (NOS) inhibitor; atropine (10 μM), a cholinergic receptor blocker; indomethacin (10 μM), a cyclooxygenase inhibitor and various K + channel blockers such as glibenclamide (10 μM) and tetraethyl ammonium (TEA 10 μM) for mechanism study. Results: SHRs receiving P. niruri extracts showed a significant decrease in their blood pressure (BP) when compared to the baseline value, with PEPN being more potent. The extracts (0.125–4 mg/mL) also induced vasorelaxation on endothelium-intact aorta rings. PEPN elicited the most potent maximum relaxation effect (Rmax ). Mechanism assessment of PEPN showed that its relaxation effect is significantly suppressed in endothelium-denuded aorta rings. Pre-incubation of aorta rings with atropine, L-NAME, ODQ, indomethacin, and propranolol also significantly attenuated its relaxation effect. Conversely, incubation with TEA and glibenclamide did not show a significant effect on PEPN-induced relaxation. Conclusion: This study indicates that the antihypertensive activity of P. niruri extract is mediated by vasoactive phytoconstituents that dilate the arterial wall via endothelium-dependent pathways and β-adrenoceptor activity which, in turn, cause vasorelaxation and reduce blood pressure. Graphical abstract: Image 1