Spectroscopic studies on the anticancer antibiotic Altromycin H and the interaction with copper(II) ions

Synthesis, chemical speciation and SOD mimic assays of tricarballylic acid–copper(II) and imidazole–tricarballylic acid–copper(II) complexes

“…Nevertheless, due to overlapping with the previous cupric complex that predominates in this experimental condition, it is not EPR detectable. The trend of g k /A k ratio is in accordance with the one expected for the increases of the negative charge of the cubic ligand field [47]. These results are in agreement with the proposed model by the potentiometric data analysis.…”

“…For the Cu 2+ /TCA 3À /H + system, in acidic medium (pH 3, curve B), two EPR signals can be observed with the typical four band pattern corresponding to an axial g tensor with hyperfine splitting due to the nuclear spin of copper(II) (I = 3/2). The first signal is related to the presence of the predominant free [Cu(H 2 O) 6 ] 2+ ion [47] (Table 2) and the other one shows that a new paramagnetic species has been formed. According to the distribution diagram this signal corresponds to the presence of [CuLH 2 ] + (I) in agreement with the fact that complexation starts at low pH in the experimental conditions.…”

“…Upon increasing the pH value of the solution the spectral feature becomes broader and the relative intensity of the signals decreases (curve D). Probably, the presence of the dinuclear species (Cu 2 L + ) (IV), that starts to be predominant, leads to signal extinguishing due to the paramagnetic Cu(II) center interactions [47,49]. Typical DMs = ±2 forbidden transition was expected to appear at half field.…”

Bioactive C-Glycosides from Bacterial Secondary Metabolism

“…Recently, complexes of altromycin B with Cu(II), Pt(II) and Pd(II) were explored, and the consequences of metal binding on DNA interactions were noted [225][226][227]. Metal complexation stabilized the drug in solution, and improved the cytotoxicity of 142 against doxorubicin-resistant lines of [225].…”

Obtención y estudio de complejos de metales de transición con moléculas bioactivas

“…La probable interacción del metal a través del grupo OH fenólico desprotonado queda descartada en base al valor calculado para la constante de acoplamiento hiperfina. Los estudios previos existentes a la interacción de este ligando con diferentes metales 56,57,58,60,61 predicen que a medida que aumenta el pH del medio, los subsiguientes puntos de interacción posibles son a través de la deprotonación y coordinación de los restos OH provenientes de los anillos fenólicos en el otro extremo de la molécula. Esto se debe esencialmente a cambios que ocurren en la distribución electrónica en el anillo de fenilo y la cadena carbonada, en efecto, el anillo adquiere una conformación quinoidal en las longitudes de los enlace C-C y ese efecto es acompañado por una modificación de la distribución electrónica de los sustituyentes para preservar la conjugación 64 .…”