title: Syntheses, calcium channel agonist-antagonist modulation activities, and nitric oxide release studies of nitrooxyalkyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate racemates, enantiomers, and diastereomers.
abstract: A novel group of hybrid calcium channel (CC) modulators was prepared where the isopropyl ester moiety of isopropyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate (PN 202-791) was replaced by a variety of nitric oxide (*NO) donor nitrooxyalkyl ester substituents. Enantiomers, or diastereomers, having the (R)-configuration at the C-4 position of the 1,4-dihydropyridine ring (1,4-DHP) exhibited more potent in vitro CC antagonist activity on guinea pig ileum longitudinal smooth muscle (GPILSM) than compounds having the (4S)-configuration. None of the nitrooxyalkyl compounds exhibited a contraindicated CC agonist effect on GPILSM that would cause smooth muscle contraction. Structure-activity studies showed the enantiomers having the (S)-configuration at the C-4 position of the 1,4-DHP ring or diastereomers having the a (4S)-configuration at the C-4 position of the 1,4-DHP ring in conjunction with a (1R-)-1-methyl-2-nitrooxyethyl ester substituent exhibited the most potent cardiac CC agonist (positive inotropic) activity on guinea pig left atrium (GPLA). This class of compounds releases *NO in vitro that is enhanced by the presence of a thiol such as N-acetylcysteamine. The novel *NO donor (-)-(S,R)-1-methyl-2-nitrooxyethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate [(-)-(S,R)-38], which acts as a dual cardioselective calcium channel agonist (GPLA)/smooth muscle selective calciumchannel antagonist (GPILSM), is a useful lead compound for drug discovery targeted to the treatment of congestive heart failure, and it provides a useful research probe to study the structure-function relationship of calcium channels.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, T6G 2N8 Canada.
authors.forename: Rudong
authors.initials: R
authors.lastname: Shan
authors.forename: Carlos
authors.initials: C
authors.lastname: Velazquez
authors.forename: Edward E
authors.initials: EE
authors.lastname: Knaus
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009206:Myocardium / Q000378:metabolism*; D009566:Nitrates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D009569:Nitric Oxide / Q000737:chemistry; D020030:Nitric Oxide Donors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D010069:Oxadiazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013237:Stereoisomerism; D013268:Stimulation, Chemical; D013329:Structure-Activity Relationship
chemical_list: C481787:1-methyl-2-nitrooxyethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D009566:Nitrates; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D009569:Nitric Oxide