Potential probe for isolation of the β-adrenoceptor, chloropractolol

Abstract

A TECHNIQUE which has proved highly successful in the isolation and identification of pharmacological receptors, is the use of a high affinity, selective label which binds irreversibly to the receptor¹. We report here our findings with a new irreversible, potent and cardioselective (β–1) β adrenoceptor antagonist, chloropractolol (I). This new compound is a modification (Fig. 1) of practolol (II), and represents the first known selective, irreversible β antagonist. Chloropractolol (I) was prepared with the intention of incorporating an alkylating function into the parent compound, while maintaining β–1 selectivity. An additional advantage of using practolol (II) rather than propranolol as the parent molecule, is that the resultant compound should, like practolol, lack nonspecific membrane stabilising effect² and any interaction with 5–hydroxytryptamine receptors³.