Abstract
The β-adrenoceptor blocking, vasorelaxant and hypotensive activities of eugenolol (1-(isopropylamino)-3-[(4- allyl-2-methoxy-)phenoxy]-2-propanol) were investigated under in vivo and in vitro conditions. In pentobarbital anesthetized rats, eugenolol (0.1, 0.5, 1.0 mg/kg, i.v.) produced a dose-dependent hypotensive and bradycardia response. Eugenolol also inhibited the tachycardia effects induced by (–)isoproterenol, but did not block arterial pressor responses induced by phenylephrine. In isolated guinea pig tissues, eugenolol competitively antagonized the (–)isoproterenol-induced positive inotropic and chronotropic effects and tracheal relaxation responses. The apparent pA2 values for eugenolol on right atria, left atria and trachea were 8.23 ± 0.04, 8.36 ± 0.13 and 8.18 ± 0.12, respectively. On tracheal strips of reserpinized guinea pig, cumulative doses of eugenolol (10–10–10–7 M) produced dose-dependent relaxant responses. Preincubating the preparation with ICI 118,551 (10–8, 10–7, 10–6 M) shifted the eugenolol concentration-relaxation curve significantly to a region of higher concentrations. Binding characteristics of eugenolol and propranolol were evaluated in [3H]dihydroalprenolol binding to pig ventricular membranes. The Ki values of eugenolol and propranolol were 18.1 ± 3.2 and 3.8 ± 0.5 nM, respectively. In guinea pig isolated thoracic aorta, eugenolol relaxed more potently the contractions induced by phenylephrine than those by high K+. The vasorelaxant effect of eugenolol on phenylephrine- or high K+-induced contraction was not attenuated by TEA or Bay K 8644 pretreatment. Furthermore, eugenolol pretreatment had a greater inhibitory effect on phenylephrine induced phasic contraction than on tonic contraction. These results indicate that eugenolol exhibits non-selective β-blocking and vasorelaxant activity by inhibiting Ca2+ channels, receptor-mediated Ca2+ mobilization and by its partial β2-agonist activity. Drug Dev. Res. 40:239–250, 1997. © 1997 Wiley-Liss, Inc.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
