Flavin-catalyzed photooxidation of an acridan drug: a reinvestigation.
Anaerobic irradiation of flavin derivatives (IIalpha and IIbeta) in the presence of 2-chloro-9-(3-dimethylaminopropyl)acridan phosphate (Ialpha) resulted in the reduction of the flavins to IValpha and IVbeta and oxidation of an equimolar amount of Ialpha to IIIalpha. This photoreduction occurred from the first excited triplet state of IIalpha and IIbeta and proceeded via a covalent intermediate (V) between flavin and the acridan derivative. If the N-10 of the acridan was blocked by a methyl group, e.g., Ic, V could be observed spectrophotometrically at -40 degrees, decomposing homolytically on warming. With N-10 unsubstituted acridan derivatives, e.g., Ialpha and Ibeta, V could not be observed because of fast heterolytic decomposition, yielding IValpha, IVbeta, and the acridine compounds IIIalpha and IIIbeta. All photoreactions showed a kinetic isotope effect between 1.50 and 2.20 when position 9 of the acridan compounds was substituted by deuterium instead of hydrogen.
D000166:Acridines / Q000528:radiation effects*; D002384:Catalysis; D005415:Flavins; D010084:Oxidation-Reduction; D010100:Oxygen; D010777:Photochemistry
D000166:Acridines; D005415:Flavins; D010100:Oxygen