title: Nitric oxide-dependent vasorelaxation induced by extractive solutions and fractions of Maytenus ilicifolia Mart ex Reissek (Celastraceae) leaves.
abstract: This study reveals that an ethanolic supernatant obtained from an aqueous extractive solution prepared from residues of methanolic extracts of ground leaves of Maytenus ilicifolia is able to cause a concentration- and endothelium-dependent relaxation in pre-contract rat aorta rings, with EC(50) of 199.7 (190-210) microg/ml. The non-selective nitric oxide synthase inhibitors l-NAME and l-NMMA abolished this effect, while superoxide dismutase and MnTBAP (a non-enzymatic superoxide dismutase mimetic) enhanced it. Further, relaxation induced by this ethanolic supernatant have been strongly inhibited by the guanylate cyclase inhibitors methylene blue and ODQ, as well as by the potassium channel blockers 4-aminopyridine and tetraethylammonium, but was unchanged by the cyclooxygenase inhibitor indomethacin and the membrane receptor antagonists atropine, HOE-140 and pirilamine. Partition of the ethanolic supernatant between H(2)O and EtOAc generated a fraction several times more potent, able to fully relax endothelium-intact aorta rings with an EC(50) of 4.3 (3.9-4.8) microg/ml. (13)C NMR spectrum of this fraction showed signals typical of catechin. This study reveals that the leaves of M. ilicifolia possess one or more potent substances able to relax endothelium-intact rat aorta rings, an event that appears to involve nitric oxide production, guanylate cyclase activation and potassium channel opening.
authors.affiliation: Department of Pharmacology, Centro Politécnico, Universidade Federal do Parana, Curitiba, PR, Brazil.
authors.forename: Yanna D
authors.initials: YD
authors.lastname: Rattmann
authors.forename: Thales R
authors.initials: TR
authors.lastname: Cipriani
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Sassaki
authors.forename: Marcello
authors.initials: M
authors.lastname: Iacomini
authors.forename: Lia
authors.initials: L
authors.lastname: Rieck
authors.forename: Maria C A
authors.initials: MC
authors.lastname: Marques
authors.forename: José E
authors.initials: JE
authors.lastname: da Silva-Santos
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D029755:Maytenus; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D016861:Cyclooxygenase Inhibitors; D010936:Plant Extracts; D026902:Potassium Channel Blockers; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D006162:Guanylate Cyclase; D007213:Indomethacin