Reactions of OH-radicals with procarbazine. A pulse radiolysis and computer simulation study.
Pulse radiolysis was applied to study the reactivity of *OH radicals with procarbazine (PC), a cytostatic agent widely used in radiation- and chemotherapy. An overall rate constant of k(*OH+PC) = 3.7 x 10(9) l.mol(-1).s(-1) was determined. The thereby formed transients had a strong absorption at 350 nm, epsilon350 = 4.46 x 10(3) l.mol(-1).cm(-1), and a weak absorption band around 530 nm. Computer simulation studies to elucidate the most probable sites of *OH attack on the PC molecule showed that *OH radical addition to the aromatic ring had the highest probability. These transients decayed by a first order reaction, k = 1.75 x 10(3) s(-1), whereby species having a maximum absorption at 300 nm and broad shoulder at 340-380 nm were formed. Similar absorptions were observed after gamma radiolysis of PC. A reaction mechanism is suggested. For the reaction of H-atoms with PC, a rate constant k(*H+PC) = 6.4 x 10(8) l.mol(-1).s(-1) was determined.
Department of Nutritional Sciences, Section Radiobiology, University of Vienna, Austria.
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Delipetar-Grudl
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Getoff
D000970:Antineoplastic Agents / Q000737:chemistry; D003198:Computer Simulation; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D011344:Procarbazine / Q000737:chemistry*; D011675:Pulse Radiolysis
D000970:Antineoplastic Agents; D017665:Hydroxyl Radical; D011344:Procarbazine