Structure-Dependent Complexation of Fe3+ by Anthracyclines. 2. The Roles of Methoxy and Daunosamine Functionalities

Molecular recognition of 3+1 hybrid human telomeric G-quadruplex DNA d-[AGGG(TTAGGG)3] by anticancer drugs epirubicin and adriamycin leads to thermal stabilization

Recent reports suggest influence of anti-cancer anthracyclines on telomere dysfunction and their possible interaction with G-quadruplex (G4) DNA as an alternate pathway to apoptosis. We have investigated interaction of epirubicin and adriamycin with G4 DNA [d-AGGG(TTAGGG)₃] comprising human telomeric DNA sequence by surface plasmon resonance, absorption, fluorescence, circular dichroism and thermal denaturation. Epirubicin and adriamycin bind with affinity, K_b, = 2.5×10⁵ and 5.2×10⁵M^-1, respectively in monomeric form leading to decrease in absorbance, fluorescence quenching and ellipticity changes without any significant shift in absorption emission maxima with corresponding induced thermal stabilization by 13.0 and 11.6°C in K⁺ rich solution. Na⁺ ions did not induce any thermal stabilization. Molecular docking confirmed external binding at grooves and loops of G4 DNA involving 4OCH₃ of ring D, 9COCH₂OH of ring A, 4'OH/H and 3'NH₃⁺ of daunosamine sugar. Thermal stabilization induced by specific interactions is likely to hamper telomere association with telomerase enzyme and contribute to drug-induced apoptosis in cancer cell lines besides causing damage to duplex DNA. The findings pave the way for drug designing in view of immense possibilities of altering substituent groups on anthracyclines for enhancement of efficacy, reduced cell toxicity as well as specificity towards G-quadruplex DNA.

First Evidence of the Liposome-Mediated Deintercalation of Anticancer Drug Doxorubicin from the Drug-DNA Complex: A Spectroscopic Approach

Biocompatible liposomes were used for the first time to study the deintercalation process of a prominent anticancer drug, doxorubicin (DOX), from doxorubicin-intercalated DNA (DOX-DNA complex) under controlled experimental conditions. The study revealed that anionic liposomes (DMPG liposomes) appeared to be the most effective to bring in the highest percentage of drug release while cationic liposomes (DOTAP liposomes) scored the lowest percentage of release. The drug release was primarily attributed to the electrostatic interaction between liposomes and drug molecules. Apart from this interaction, changes in the hydrophobicity of the medium upon addition of liposomes to the DNA-drug solution accompanied by lipoplex formation between DNA and liposomes were also attributed to the observed deintercalation. The CD and the time-resolved rotational relaxation studies confirmed that lipoplex formation took place between liposomes and DNA owing to electrostatic interaction. The confocal study revealed that in the postrelease period, DOX binds with liposomes. The reason behind the binding is electrostatic interaction as well as the unique bilayer structure of liposomes which helps it to act as a "hydrophobic sink" for DOX. The study overall highlighted a novel strategy for deintercalation of drug using biocompatible liposomes, as the release of the drug can be controlled over a period of time by varying the concentration and composition of the liposomes.

Isolation of doxorubicin from a bacterial culture using immobilised metal ion affinity chromatography

Doxorubicin was isolated as a free ligand from aStreptomyces peucetiusvar.caesiusculture using Ni(ii)-based IMAC. This easy-to-use, water-compatible method could improve the security of doxorubicin supply.

Host-guest interactions in Fe(III)-trimesate MOF nanoparticles loaded with doxorubicin

Doxorubicin (DOX) entrapment in porous Fe(III)-trimesate metal organic frameworks (MIL-100(Fe)) nanoparticles was investigated in neutral Tris buffer via UV-vis absorption, circular dichroism (CD), and fluorescence. The binding constants and the absolute spectra of the DOX-MIL-100(Fe) complexes were determined via absorption and fluorescence titrations. A binding model where DOX associates as monomer to the dehydrated Fe3O (OH)(H2O)2 [(C6H3)(CO2)3]2 structural unit in 1:1 stoichiometry, with apparent association constant of (1.1 to 1.8) × 10(4) M(-1), was found to reasonably fit the experimental data. Spectroscopic data indicate that DOX binding occurs via the formation of highly stable coordination bonds between one or both deprotonated hydroxyl groups of the aglycone moiety and coordinatively unsaturated Fe(III) centers. Complete quenching of the DOX fluorescence and remarkable thermal and photochemical stability were observed for DOX incorporated in the MIL-100(Fe) framework.

Interactions of doxorubicin with organized interfacial assemblies. 2. Spectroscopic characterization

Doxorubicin is an anthracycline that has found wide use as a chemotherapeutic agent, with the primary limitation to its use being cardiotoxicity. Depending on the identity and location of pendent side groups, the anthracyclines exhibit varying degrees of chemotherapeutic activity and toxicity, and a key area of research activity lies in understanding how the structure of the anthracycline influences its interactions with amphiphilic interfaces. We have studied interactions between doxorubicin and interfacial adlayers of octadecylamine (C18NH2), dihexadecylphosphate (DHP), and both monolayers and bilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) on mica using time- and frequency-resolved spectroscopic measurements. We report surface-enhanced resonance Raman data and fluorescence lifetime and anisotropy imaging data for doxorubicin at these interfaces. For all monolayers, there is a substantial interaction between doxorubicin and the interface. For DMPC bilayers, the extent of the interaction between doxorubicin and the interface depends on how the interface was formed.