RESUMO
4'-Epiadriamycin is a better-tolerated anthracycline drug, due to lesser cardiotoxicity. We report here a study of the 2:1 complex of 4'-epiadriamycin-d-(CGATCG)(2) by proton Nuclear Magnetic Resonance Spectroscopy which show the absence of sequential connectivities between C1pG2 and C5pG6 base pair steps and presence of intermolecular cross peaks of the drug and DNA. Our studies establish the role of 9OH, NH3+, 7O, 4OCH(3) groups in binding to DNA. Time-resolved fluorescence measurement and diffusion ordered spectroscopic studies reveal the formation of complex. The nonspecific interactions as well as those essential for biological activity are discussed along with its medicinal importance.
Assuntos
Antibióticos Antineoplásicos/química , Epirubicina/análogos & derivados , Epirubicina/química , Oligodesoxirribonucleotídeos/química , Antibióticos Antineoplásicos/síntese química , Sequência de Bases , Simulação por Computador , DNA/química , Epirubicina/síntese química , Corantes Fluorescentes/química , Ressonância Magnética Nuclear Biomolecular , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/síntese química , Estrutura Terciária de Proteína , Soluções/química , Relação Estrutura-Atividade , Termodinâmica , Fatores de TempoRESUMO
Self-association, a process that competes with binding to DNA and formation of hetero-complexes, is studied in anticancer drugs 4'-epiadriamycin, adriamycin and daunomycin by proton nuclear magnetic resonance spectroscopy. The 2D nuclear Overhauser enhancement spectra yield several intra-molecular and inter-molecular inter-proton connectivities suggesting specific stacking patterns of aromatic chromophores in parallel and anti-parallel orientation. Absorption, emission and diffusion ordered spectroscopy demonstrate the formation of self-aggregates. Electron spray ionization mass spectrometry gives a direct proof of the presence of dimer and absence of higher aggregates. The restrained molecular dynamics simulations show the structural differences between drugs, which have been correlated to the biological action. A clear evidence of reduced cardiotoxicity by 4'-epiadriamycin, as compared to daunomycin and adriamycin, is demonstrated by mass spectrometry data.
Assuntos
Antraciclinas/química , Difusão , Modelos Moleculares , Absorção , Antraciclinas/farmacologia , Antraciclinas/toxicidade , Antineoplásicos/química , Antineoplásicos/farmacologia , Antineoplásicos/toxicidade , Espectroscopia de Ressonância Magnética , Espectrometria de Fluorescência , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
The anthracycline antibiotic daunomycin, having four fused rings and an amino sugar, is being used in the treatment of acute leukemia. Binding to DNA is generally believed to be essential for its activity. We have studied the interaction of daunomycin with DNA hexamer sequence d-(TGATCA)2 by titrating up to two drug molecules per duplex using nuclear magnetic resonance spectroscopy. The solution structure of 2:1 drug to DNA complex based on two dimensional nuclear Overhauser enhancement (NOE) spectroscopy and molecular dynamics calculations has been studied. The change in conformation of drug molecule on binding to DNA, deoxyribose conformation and glycosidic bond rotation has been obtained. The absence of sequential NOE connectivities at d-T1pG2 and d-C5pA6 sites shows that the drug chromophore intercalates between these two base pairs. This is substantiated by intermolecular NOEs observed between nucleotide base protons and aromatic ring protons of drug molecule. A set of 17 intermolecular NOE interactions allowed the structure to be derived by restrained molecular dynamics simulations, which have been compared with that obtained by X-ray analysis. Several specific interactions between the drug and DNA protons are found to stabilize the formation of drug-DNA complex.
Assuntos
Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/metabolismo , DNA/química , Daunorrubicina/química , Daunorrubicina/metabolismo , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Conformação de Ácido Nucleico , Conformação Proteica , PrótonsRESUMO
Adriamycin is an anthracycline anticancer drug used widely for solid tumors in spite of its adverse side effects. The solution structure of 2:1 adriamycin-d-(CGATCG)(2) complex has been studied by restrained molecular dynamics simulations. The restraint data set consists of several intramolecular and intermolecular nuclear Overhauser enhancement cross-peaks obtained from two-dimensional nuclear magnetic resonance spectroscopy data. The drug is found to intercalate between CG and GC base pairs at two d-CpG sites. The drug-DNA complex is stabilized via specific hydrogen bonding and van der Waal's interactions involving 4OCH(3), O5, 6OH, and NH(3)(+) moiety of daunosamine sugar, and rings A protons. The O-glycosidic bond C7-O7-C1'-C2' lies in the range 138 degrees -160 degrees during the course of simulations. The O6-H6...O5 hydrogen bond is stable while O11-H11...O12 hydrogen bond is not favored. The intercalating base pairs are buckled and minor groove is wider in the complex. The phosphate on one strand at intercalation site C1pG2 is in B(I) conformation and the phosphates directly lying on opposite strand is in B(II) conformation. The phosphorus on adjacent site G2pA3 is in B(II) conformation and hence a distinct pattern of B(I) and B(II) conformations is induced and stabilized. The role of various functional groups by which the molecular action is mediated has been discussed and correlated to the available biochemical evidence.
