Bioanalytical studies of the DNA binding profiles of new metallopharmaceuticals

This dissertation discusses the research efforts used to study the interactions of two prototypical metallopharmaceuticals with their primary biological target, DNA. The studies focus on the binding profiles of [PtCl(en)(ACRAMTU)](NO 3)2 (PT-ACRAMTU; en = ethane-1,2-diamine; ACRAMTU = 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea) and [Rh(NH3)5(ACRTMTU)](CF3SO3) 4(RH-ACRTMTU; ACRTMTU = 1-[2-(acridin-9-ylamino)ethyl]-1,3,3-trimethylthiourea).; The interaction of PT-ACRAMTU with 2'-deoxyguanosine (dGuo) and random-sequence calf thymus DNA was studied using LC-MS and NMR spectroscopy. These techniques were utilized to identify the site of DNA modification by platinum. Analysis of the reactions of PT-ACRAMTU in the dGuo model system revealed the presence of two adducts. The major adduct was determined to be [Pt(en)(ACRAMTU)(dGuo-N7)]3+ while the minor adduct was identified as [Pt(en)(dGuo-N7)2]2+. Enzymatic digests of native DNA incubated with PT-ACRAMTU resulted in three adducts. The first and most abundant adduct was identified as [Pt(en)(ACRAMTU)(dGuo-N7)]3+, which proved to be identical to the major adduct in the mononucleoside model system.; The formation of platinum-modified adenine adducts was further studied through the use of analytical and high-resolution structural methods. The development and use of an adenine specific depurination assay, inspired by previous reports illustrating that in acidic media metal-modified adenine undergoes depurination while guanine complexes do not, aided in the ability to produce adenine adducts in sufficient quantities for analysis. Using single- and double-stranded model sequences as well as double-stranded native DNA, the adduct profile of PT-ACRAMTU was studied. The newly developed assay was used to selectively release platinum modified adenine bases from the drug treated DNA.; Finally, Chapter 4 presents the studies towards the development of a light-activatable rhodium(III) compound analogous to the previously developed platinum-acridine complexes. The design rationale, synthesis, and characterization of ACRAMTU, [Rh(NH3)5(tmtu)](CFSO 3)3 (RH-TMTU; tmtu = 1,1,3,3-tetramethylthiourea), and RH-ACRTMTU are discussed. Through 15N{lcub}1H{rcub} NMR spectroscopy experiments using 15N-labeled RH-TMTU, the ligand-field photo-hydrolysis and photo-isomerization of the thermally inert rhodium(III) compounds was followed. The affinity of RH-TMTU and RH-ACRTMTU to native DNA was studied by ICP-AES. This revealed that the levels of DNA binding by RH-TMTU and RH-ACRTMTU did not show light-enhanced formation of adducts. (Abstract shortened by UMI.)...