The L-Type Calcium Channel Blockers, Hantzsch 1,4-Dihydropyridines, Are Not Peroxyl Radical-Trapping, Chain-Breaking Antioxidants

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TypeArticle
Journal titleChem. Res. Toxicol.
Chemical Research in Toxicology
ISSN0893-228x
Volume19
Issue1
Pages7985; # of pages: 7
AbstractThe antioxidant properties of Hantzsch 1,4-dihydropyridine esters and two dibenzo-1,4-dihydropyridines, 9,10-dihydroacridine (DHAC) and N-methyl-9,10-dihydroacridine (N-Me-DHAC), have been explored by determining whether they retard the autoxidation of styrene or cumene at 30 C. Despite a claim to the contrary [(2003) Chem. Res. Toxicol. 16, 208-215], the Hantsch esters were found to be virtually inactive as chain-breaking antioxidants (CBAs), their reactivity toward peroxyl radicals being some 5 orders of magnitude lower than that of the excellent CBA, 2,2,5,7,8-pentamethyl-6-hydroxy-chroman (PMHC). DHAC was found to be about a factor of 10 less reactive than PMHC. From kinetic measurements using DHAC, N-deuterio-DHAC, and N-Me-DHAC, it is concluded that it is the N-H hydrogen in DHAC that is abstracted by peroxyl radicals, despite the fact that in DHAC the calculated C-H bond dissociation enthalpy (BDE) is about 11 kcal/mol lower than the N-H BDE. The rates of hydrogen atom abstraction by the 2,2-diphenyl-1-picrylhydrazyl radical (dpph) have also been determined for the same series of compounds. The trends in the peroxyl and dpph rate constants are similar.
Publication date
Linkhttp://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/tx0502591
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
Identifier10439298
NPARC number12327822
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Record identifier75592a86-2cb4-41b4-90a5-f6e5a503b585
Record created2009-09-10
Record modified2016-05-09
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