Dias, CPaulo, ANascimento, JHoughton, PHawkes, JEGoncalves, ML2015-12-302015-12-302003PLANTA MEDICA. - Vol. 69, n. 11 (NOV 2003), p. 1060-10620032-0943http://hdl.handle.net/10451/21358A new natural pyrimidine derivative, 2-(4'-aminobenzenamine)pyrimidine (1), was isolated from the bulbs of Autonoe madeirensis, a Hyacinthaceae of the Madeira Archipelago (Portugal) and the structure determined on the basis of spectroscopic data. As some pyrimidine compounds are important alpha(1)-adrenergic antagonists, we investigated the effect of 1 on rat vas deferens contractility induced by the alpha(1)-agonist phenylephrine. In concentrations virtually devoid of effect on the rat vas deferens contractility, 1 shifted to the right the concentration-response curves of phenylephrine without changing the maximal effect. These results provide evidence that 1 acts as an alpha(1)-adrenoceptor antagonist and suggest a competitive mechanism of action.application/pdfengPlant SciencesChemistry, MedicinalPharmacology & Pharmacyjournal article