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ANTHRACYCLINE COPPER(II) COMPLEXES - STRUCTURE-DEPENDENT COORDINATION PATTERN AS EVIDENCED BY ELECTRON-SPIN-RESONANCE
No full textThe copper(II) coordination properties of different anthracycline antitumor agents were studied by ESR spectroscopy. Three classes of drugs have been identified: (i) adria-like, which contains adriamycin, daunomycin, 4′-deoxydaunomycin, 4′-deoxy- 4′-iododaunomycin and 4-demethoxydaunomycin; (ii) 4′-epiadria-like, which contains 4′-epiadriamycin, 4′-epidaunomycin, 4-demethoxy-6-deoxydaunomycin and 4-demethoxy-11-deoxydaunomycin; and (iii) border-line type, which contains carminomycin, 6-O- methylcarminomycin, 11-deoxycarminomycin and 6- deoxycarminomycin. They have been characterized by their different Cu(II) chelation properties. The adria-like class members give rise to multi- nuclear complexes, where both the CO and COH functionalities of both sides of the hydroxyanthra- quinone system are involved in the coordination. By contrast, the 4′-epiadria-like drugs form monomeric Cu(II) complexes because of the unavailability of the C(6)OH group. The border-line type compounds yield more than one monomeric Cu(II)adduct because of the presence of OH at the C(4) position. All Cu(II) derivatives are characterized by a very strong ligand field, the unpaired electron lying in the dx2-y2 orbital. The onset of comptexation is oxygen dependent and this is related to the σ and π bond properties of the anthracycline ligand
Photochromism and thermochromism of spiro[indolinoxazines] in normal and reversed micelles
No full textCHELATION OF COPPER(II) IONS BY DOXORUBICIN AND 4'-EPIDOXORUBICIN - ELECTRON-SPIN-RESONANCE EVIDENCE FOR A NEW COMPLEX AT HIGH ANTHRACYCLINE COPPER MOLAR RATIOS
No full textDoxorubicin and 4′-epidoxorubicin form chelate complexes with Cu(II), the structures of which are dependent on the drug-to-metal ratio r. The complex stoichiometry is defined by the structure of the drug, the pH and the r values. The cupric ion is able to evidence minor structural differences (doxorubicin versus 4′-epidoxorubicin), the substitution pattern of the antraquinone moiety and the self-association of the anthracycline ligand
"Photocytotoxicity of anthracyclines upon laser excitation in their long-wavelength absorption bands"
No full textChelation of copper(II) by daunomycin and 5-iminodaunomycin and interaction of the complexes with mononucleotides: An ESR study
No full textCoordination of copper(II) ions by daunomycin and 5-iminodaunomycin has been studied by electron spin resonance spectroscopy, at various values of pH and r, the anthracycline-to-Cu(II) molar ratio. At r = 1–5, polymeric complexes are formed in the case of daunomycin. At r = 5, a mononuclear complex is predominant and at r = 10, this is the only one formed with the 63Cu and 65Cu hyperfine interaction being clearly defined in the g∥ region (g∥ = 2.26, 63A∥ = 175; 65A∥ = 190 G). For 5-iminodaunomycin both chelation sites are involved in the coordination and a polymeric structure (in which exchange interactions between Cu(II) centers operate) is stable in the range r = 1–3. At r = 3, the triplet state of a dinuclear Cu(II) complex is observed and 5-iminodaunomycin behaves as both a bridging and a terminal ligand. For r = 5–10, the dinuclear complex coexists with the mononuclear one. In the presence of mononucleotides dGMP, dAMP, dCMP and thymidine, no ternary complex such as mononucleotide/Cu(II)/anthracycline was observed
Enhancement of antitumor drug cytotoxicity via laser photoactivation.
No full textWe investigate the efficacy of daunomycin, some imino- and amino-substituted daunomycin analogues and the disubstituted aminoanthracenedione, mitoxantrone, in photosensitizing short-term cell kill upon irradiation in the long wavelength visible range, during incubation of Fisher rat thyroid cells with the drugs. While all compounds exhibit similar cytocidal effects on our cell line, in the absence of irradiation, administering 86 J/cm2 at wavelengths either coincident or close to drug absorption peaks causes greater enhancement in cell mortality for the 4-demethoxydaunomycin analogues than either the parent drug or its 5-imino-derivative. A lower enhancement is observed with mitoxantrone. In particular, C50 doses (i.e. concentrations that would kill 50% cells) as low as approximately 10(-9) M are found for both 6- and 11-amino 4-demethoxydaunomycin, compared with the values obtained in the absence of light, which are 2.59 x 10(-4) and 0.43 x 10(-4) M, respectively. Our previous studies of the photophysical and photochemical properties of the excited states of these drugs, and ESR and spin trapping studies of photosensitized generation of singlet oxygen, which were extended in this work to include mitoxantrone, indicate that the cytocidal effects proceed via type I rather than type II mechanisms
CHELATION OF COPPER(II) IONS BY DOXORUBICIN AND 4'-EPIDOXORUBICIN - AN ELECTRON-SPIN-RESONANCE STUDY
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