A series of vanilloid-type β-adrenoceptor blockers derived from traditional Chinese herbal medicines were synthesized and tested for their antioxidant and adrenoceptor antagonistic activities. They all possessed significant β-adrenoceptor blocking activities under in vitro experiments and radioligand binding assays. In addition, some compounds were further examined in in vito tests and produced antagonist effects matching that of propranolol and labetalol by measurements of antagonism toward (-)isoproterenol-induced tachycardia and (-)phenylephrine-induced pressor responses in anesthetized rats. Furthermore, all of the compounds had antioxidant effects inherited from their original structures. In conclusion, compound 11 had the most potent β-adrenoceptors blocking activity, 12 and 13 possessed high cardioselectivity, whereas 14, 15 and 16 possessed additional α-adrenoceptor blocking activity and 15 is the most effective antioxidant of all. the antioxidant activity may be due to their @alpha; and β unsaturated side chain at position 1 and ortho-substituted methoxy moiety on 4-phenoxyethylamine.
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