title: Novel potassium channel activators. II. Synthesis and pharmacological evaluation of 3,4-dihydro-2H-1,4-benzoxazine derivatives: modification of the aromatic part.
abstract: Three new series of analogues related to 3,4-dihydro-2H-1,4-benzoxazine derivative 1a were synthesized and evaluated for their potassium channel activating activity. In the first series I, where the 6,7-positions were disubstituted, it was found that an electron-withdrawing substituent was preferable at the 6 position, but either an electron-withdrawing or releasing substituent without bulkiness was tolerated at the 7 position. In the second series II, where several heterocycles were introduced into the 6,7-positions, the oxadiazole derivative 6 showed more potent activity than cromakalim. In the third series III, where the benzene ring was replaced by a pyridine ring, borane complex 16 had equivalent activity to cromakalim. Especially, compound 6 showed a potent hypotensive effect with a long duration of action in the spontaneous hypertensive rat and had a lesser increasing effect on intracranial pressure in dogs than 1a and levcromakalim, showing a good profile as an antihypertensive agent.
authors.affiliation: Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Ibaraki, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: R
authors.initials: R
authors.lastname: Tsuzuki
authors.forename: A
authors.initials: A
authors.lastname: Matsuhisa
authors.forename: N
authors.initials: N
authors.lastname: Masuda
authors.forename: Y
authors.initials: Y
authors.lastname: Yamagiwa
authors.forename: I
authors.initials: I
authors.lastname: Yanagisawa
authors.forename: T
authors.initials: T
authors.lastname: Shibanuma
authors.forename: H
authors.initials: H
authors.lastname: Nohira
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects; D019806:Cromakalim / Q000737:chemistry / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004285:Dogs; D005260:Female; D006973:Hypertension / Q000188:drug therapy; D066298:In Vitro Techniques; D007427:Intracranial Pressure / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010078:Oxazines / Q000138:chemical synthesis* / Q000494:pharmacology; D015221:Potassium Channels / Q000819:agonists*; D051381:Rats; D011918:Rats, Inbred SHR; D013329:Structure-Activity Relationship
chemical_list: D000959:Antihypertensive Agents; D010078:Oxazines; D015221:Potassium Channels; D019806:Cromakalim