Comparison of the nucleic acid covalent binding capacity of two nitro-substituted benzazolo[3,2-a]quinolinium salts upon enzymatic reduction.
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.
Zayas
Beatriz
B
School of Environmental Affairs, Universidad Metropolitana, San Juan, Puerto Rico. bzayas@suagm.edu
Beyley
Juan
J
Terron
Maria
M
Cordero
Marisol
M
Hernandez
Wigberto
W
Alegría
Antonio E
AE
Cox
Osvaldo
O
D000970:Antineoplastic Agents / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000378:metabolism; D018736:DNA Adducts; D019271:Hypoxanthine / Q000378:metabolism; D010084:Oxidation-Reduction; D011355:Prodrugs / Q000378:metabolism; D011806:Quinolinium Compounds / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D014969:Xanthine Oxidase / Q000378:metabolism
D000970:Antineoplastic Agents; D018736:DNA Adducts; D011355:Prodrugs; D011806:Quinolinium Compounds; D019271:Hypoxanthine; D004247:DNA; C427203:calf thymus DNA; D014969:Xanthine Oxidase