Indole-phenol bioisosterism. Synthesis and antihypertensive activity of a pyrrolo analogue of labetalol.
The synthesis of 5-[hydroxy-2-[(1-methyl-3-phenylpropyl)amino]ethyl]-1H-indole-7- carboxamide, 5, a pyrrolo analogue of labetalol, is described. Compound 5 was found to reduce blood pressure in spontaneously hypertensive rats with an ED50 of 5 mg/kg po, without causing any decrease in heart rate. Isolated tissue studies with 5 shows that it is a nonselective beta-adrenoceptor antagonist and that it is a weaker alpha-adrenoceptor antagonist with a relative selectivity for alpha 1-receptors. Additionally, the compound displayed significant beta-adrenoceptor intrinsic sympathomimetic activity. Evidence is presented that the beta-adrenoceptor antagonist and agonist properties of 5 are mediated via hydrogen-bond formation with the receptor.
D000818:Animals; D000959:Antihypertensive Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D006860:Hydrogen Bonding; D066298:In Vitro Techniques; D007741:Labetalol / Q000031:analogs & derivatives*; D051381:Rats; D011918:Rats, Inbred SHR; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D013329:Structure-Activity Relationship
D000959:Antihypertensive Agents; D011943:Receptors, Adrenergic, beta; D007741:Labetalol