Enantioselective synthesis and pharmacological evaluation of a new type of verapamil analog with hypotensive and calcium antagonist activities.
OBJECTIVE
The syntheses and evaluation for cardiovascular activity in the rat of both enantiomers of a verapamil analog in which the cyano group has been replaced by hydroxyl.


METHODS
(+)- and (-)-alpha-[3-[[2-(3,4-Dimethoxyphenyl)ethyl]methylamino]propyl]- 3,4-dimethoxy-alpha-(1-methyl ethyl)benzyl alcohol were prepared from chiral sulfoxides produced by microbial biotransformations using Mortierella isabellina ATCC 42613 or Helminthsporium species NRRL 4671, and were examined for hypotensive and calcium antagonist activity using anaesthetized normotensive rats and isolated rat aorta and atria.


RESULTS
The analogs showed a pharmacological profile similar to that exhibited by verapamil, possessing a remarkable hypotensive activity, accompanied by a significant bradycardia, in anaesthetized normotensive rats. In vitro, these analogs displayed clear inhibitory effects: in isolated rat aorta they inhibited, in a concentration-dependent fashion, the contractions and 45Ca2+ uptake induced by norepinephrine and high KCl, and in isolated rat atria the analogs considerably decreased the rate of contraction (negative chronotropic effects). No significant differences between the quantitative cardiovascular effects produced by the two enantiomers of the verapamil analogs were observed.


CONCLUSIONS
The results suggest that, like that of verapamil, the cardiovascular activity exhibited by the new compounds seems to be due, at least in part, to a blockage of transmembrane calcium channels present in vascular smooth muscle cells.
Holland
H L
HL
Department of Chemistry, Brock University, St. Catharines, Ontario, Canada. holland@chemiris.labs.brocku.ca
Gu
J X
JX
Orallo
F
F
Camiña
M
M
Fabeiro
P
P
Willetts
A J
AJ
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D016275:Atrial Function / Q000187:drug effects; D001711:Biotransformation; D002121:Calcium Channel Blockers / Q000138:chemical synthesis / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006375:Helminthosporium / Q000378:metabolism; D007022:Hypotension / Q000139:chemically induced*; D066298:In Vitro Techniques; D008297:Male; D020094:Mortierella / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D013237:Stereoisomerism; D014661:Vasoconstriction / Q000187:drug effects*; D014700:Verapamil / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D014700:Verapamil