title: Hantzsch 1,4-dihydropyridines containing a diazen-1-ium-1,2-diolate nitric oxide donor moiety to study calcium channel antagonist structure-activity relationships and nitric oxide release.
abstract: A group of racemic 3-isopropyl 5-[(2-piperazin-1-yl)ethyl] 1,4-dihydro-2,6-dimethyl-4-(pyridyl)-3,5-pyridinedicarboxylates (12a-c), 3-isopropyl 5-{2-[4-nitrosopiperazinyl]ethyl} 1,4-dihydro-2,6-dimethyl-4-(pyridyl)-3,5-pyridinedicarboxylates (14a-c) and 3-isopropyl 5-{2-[(O(2)-acetoxymethyldiazen-1-ium-1,2-diolate)(N,N-dialkylamino or 4-piperazin-1-yl)]ethyl} 1,4-dihydro-2,6-dimethyl-4-(pyridyl)-3,5-pyridinedicarboxylates (22-30) were prepared using modified Hantzsch reactions. This group of compounds (12a-c, 14a-c, and 22-30) exhibited less potent calcium channel antagonist activity (IC(50)=0.11 to 3.35muM range) than the reference drug nifedipine (IC(50)=0.01 microM). The point of attachment of the isomeric C-4 substituent was a determinant of calcium channel antagonist activity providing the potency profile 2-pyridyl3-pyridyl4-pyridyl. The N-nitrosopiperazinyl compounds (14a-c) did not release nitric oxide. The prodrugs 22-30 that have a C-5 2-[(O(2)-acetoxymethyldiazen-1-ium-1,2-diolate)(N,N-dialkylamino or 4-piperazin-1-yl)]ethyl ester substituent, upon incubation with guinea pig serum, undergo consecutive cleavage of the O(2)-acetoxymethyl moiety to give a nitric oxide donor diazenium-1-ium-1,2-diolate species that subsequently releases nitric oxide. The extent of nitric oxide released from the diazen-1-ium-1,2-diolate group is dependent upon the nature of the amino functionality attached directly to the diazen-1-ium N-1 position where the nitric oxide release profile is 1,4-piperazinyl>N-Et>N-(n-Bu)>>N-Me upon exposure to guinea pig serum esterase(s). The results from this study suggest this class of hybrid calcium channel antagonist/nitric oxide donor prodrugs should release the vasodilator nitric oxide in vivo, preferentially in the vascular endothelium, to enhance the smooth muscle calcium channel antagonist effect to produce a combined synergistic antihypertensive effect.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2N8.
authors.forename: Jeffrey-Tri
authors.initials: JT
authors.lastname: Nguyen
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Velázquez
authors.forename: Edward E
authors.initials: EE
authors.lastname: Knaus
mesh_terms: D000818:Animals; D001391:Azo Compounds / Q000032:analysis*; D002121:Calcium Channel Blockers / Q000737:chemistry / Q000494:pharmacology*; D004095:Dihydropyridines / Q000737:chemistry / Q000494:pharmacology*; D006168:Guinea Pigs; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000032:analysis*; D013329:Structure-Activity Relationship
chemical_list: D001391:Azo Compounds; D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D020030:Nitric Oxide Donors; C452539:diazeniumdiolate; D009569:Nitric Oxide; C038806:1,4-dihydropyridine