Comparison of the nucleic acid covalent binding capacity of two nitro-substituted benzazolo[3,2-a]quinolinium salts upon enzymatic reduction
- 作者：Beatriz Zayas ; Juan Beyley ; Maria Terron ; Marisol Cordero ; Wigberto Hern ; ez ; Antonio E. Alegrí ; a ; Osvaldo Cox
- 关键词：DNA adducts ; Bioreductive drugs ; Benzazolo[3 ; 2-a]quinolinium ; Hypoxia ; Mass spectrometry
- 刊名：Toxicology in Vitro
- 出版年：2007
- 期刊代码：48_08872333
- 类别：pha
- 出版时间：September 2007
- 卷：21
- 期：6
- 页码：1155-1164
- 文件大小：485 K
摘要
The DNA binding capacity of two nitro-substituted benzazolo[3,2-a]quinolinium chlorides (NBQs), NBQ-38 and NBQ-95, was evaluated upon their enzymatic reduction with hypoxanthine (HX)/xanthine oxidase (XO) under anaerobic conditions. In the presence of 2′-deoxyguanosine (2′-dG) or calf thymus DNA, covalent-addition products were monitored. Reactions of each NBQ with 2′-dG or DNA differed in the NBQ to HX molar ratio. Control reactions, one without HX/OX and another under aerobic conditions, were also analyzed. Adducts were isolated and characterized by high performance liquid chromatography (HPLC) and electrospray ionization-mass spectrometry (ESI-MS). Authentic samples of the reduced forms of these NBQs, identified as ABQ-38 and ABQ-95, were synthesized as standards to monitor bioreduction processes. HPLC analysis showed that the yield of formation of an unknown product (possibly, 2′-dG-NHBQ-38 adduct) from the reaction of NBQ-38 with 2′-dG and DNA was proportional to the HX to NBQ-38 molar ratio. ESI-MS analysis of the DNA hydrolysates showed evidence of an adduct formed upon bioreduction of NBQ-38 by the ions detection at m/z 528.3 and 454.8, consistent with chemical structures of a 2′-dG-NHBQ-38 adduct and a fragment ion. DNA adducts were not observed with NBQ-95, although the corresponding bioreduction product ABQ-95 was detected by ESI-MS. This study provides mechanistic information of these bioreductively-activated pro-drugs with potential therapeutic applications.