DNA damage induced by the anthracycline cosmomycin D in DNA repair-deficient cells

Anthracyclines have been widely used as antitumor agents, playing a crucial role in the successful treatment of many types of cancer, despite some side effects related to cardiotoxicity. New anthracyclines have been designed and tested, but the first ones discovered, doxorubicin and daunorubicin, continue to be the drugs of choice. Despite their extensive use in chemotherapy, little is known about the DNA repair mechanisms involved in the removal of lesions caused by anthracyclines. The anthracycline cosmomycin D is the main product isolated from Streptomyces olindensis, characterized by a peculiar pattern of glycosylation with two trisaccharide rings attached to the A ring of the tetrahydrotetracene. We assessed the induction of apoptosis (Sub-G(1)) by cosmomycin D in nucleotide excision repair-deficient fibroblasts (XP-A and XP-C) as well as the levels of DNA damage (alkaline comet assay). Treatment of XP-A and XP-C cells with cosmomycin D resulted in apoptosis in a time-dependent manner, with highest apoptosis levels observed 96 h after treatment. The effects of cosmomycin D were equivalent to those obtained with doxorubicin. The broad caspase inhibitor Z-VAD-FMK strongly inhibited apoptosis in these cells, and DNA damage induced by cosmomycin D was confirmed by alkaline comet assay. Cosmomycin D induced time-dependent apoptosis in nucleotide excision repair-deficient fibroblasts. Despite similar apoptosis levels, cosmomycin D caused considerably lower levels of DNA damage compared to doxorubicin. This may be related to differences in structure between cosmomycin D and doxorubicin.

Spectroscopic Investigation on the Formation of a Dinuclear Me(2)SO-Ru(2)-Mercaptopyridine Bridged Complex: [Ru(2)Cl(3)(mu-pyS)(mu-dmso)(dmso)(4)]center dot 2H(2)O

A dinuclear ruthenium(II) complex double-bridged by an N-aromatic ligand 2-mercaptopyridine (2-pyridinethiol or 2-pyridyl mercaptan) and a methyl sulfoxide (dmso) have been characterized by X-ray crystallography. The reported compound with formula [Ru(2)Cl(3) (mu-pyS)(mu-dmso)(dmso)(4)] center dot 2H(2)O, [C(15)H(36)Cl(3)NO(7)S(6)Ru(2)] (P2/c, a = 13.8175(2) angstrom, b = 10.5608(2) angstrom, c = 21.3544 (3) angstrom, beta = 106.090(1)degrees, V = 2,994.05(8) angstrom(3), Z = 4) represents a seven-membered ring system with both rutheniums in an octahedral geometry. All the hydrogen bonds (C-H-Cl) and the van der Waals contacts give rise to three-dimensional network in the structure and add stability to the dinuclear compound. To our knowledge, this is the first time that the formation of a dinuclear ruthenium(II) complex double-bridged by an N-aromatic ligand 2-mercaptopyridine and dmso have been reported. The study also provided valuable insight into bioinorganic chemistry as continuing efforts are being made to develop metal-based cancer chemotherapeutics. A major feature of this paper is the resolution of a double bridged ruthenium structure which contributes to a better understanding of ruthenium reactivity.

Immobilization of lutetium bisphthalocyanine in nanostructured biomimetic sensors using the LbL technique for phenol detection

This study describes the development of amperometric sensors based on poly(allylamine hydrochloride) (PAH) and lutetium bisphthalocyanine (LuPc(2)) films assembled using the Layer-by-Layer (LbL) technique. The films have been used as modified electrodes for catechol quantification. Electrochemical measurements have been employed to investigate the catalytic properties of the LuPc(2) immobilized in the LbL films. By chronoamperometry, the sensors present excellent sensitivity (20 nA mu M(-1)) in a wide linear range (R(2) = 0.994) up to 900 mu M and limit of detection (s/n = 3) of 37.5 x 10(-8) M for catechol. The sensors have good reproducibility and can be used at least for ten times. The work potential is +0.3 V vs. saturated calomel electrode (SCE). In voltammetry measurements, the calibration curve shows a good linearity (R(2) = 0.992) in the range of catechol up to 500 mu M with a sensitivity of 90 nA mu M(-1) and LD of 8 mu M. (C) 2011 Elsevier B.V. All rights reserved.

A short proregion of trialysin, a pore-forming protein of Triatoma infestans salivary glands, controls activity by folding the N-terminal lytic motif

Triatoma infestans (Hemiptera: Reduviidae) is a hematophagous insect that transmits the protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas` disease. Its saliva contains trialysin, a protein that forms pores in membranes. Peptides based on the N-terminus of trialysin lyse cells and fold into alpha-helical amphipathic segments resembling antimicrobial peptides. Using a specific antiserum against trialysin, we show here that trialysin is synthesized as a precursor that is less active than the protein released after saliva secretion. A synthetic peptide flanked by a fluorophore and a quencher including the acidic proregion and the lytic N-terminus of the protein is also less active against cells and liposomes, increasing activity upon proteolysis. Activation changes the peptide conformation as observed by fluorescence increase and CD spectroscopy. This mechanism of activation could provide a way to impair the toxic effects of trialysin inside the salivary glands, thus restricting damaging lytic activity to the bite site.

Multivariant optimization, validation, and application of capillary electrophoresis for simultaneous determination of polyphenols and phenolic acids in Brazilian wines

A method for the simultaneous determination of the stilbene resveratrol, four phenolic acids (syringic, coumaric, caffeic, and gallic acids), and five flavonoids (catechin, rutin, kaempferol, myricetin, and quercetin) in wine by CE was developed and validated. The CE electrolyte composition and instrumental conditions were optimized using 2(7-3) factorial design and response surface analysis, showing sodium tetraborate, MeOH, and their interaction as the most influential variables. The optimal electrophoretic conditions, minimizing the chromatographic resolution statistic values, consisted of 17 mmol/L sodium tetraborate with 20% methanol as electrolyte, constant voltage of 25 kV, hydrodynamic injection at 50 mbar for 3 s, and temperature of 25 degrees C. The R(2) values for linearity varied from 0.994 to 0.999; LOD and LOQ were 0.1 to 0.3 mg/L and 0.4 to 0.8 mg/L, respectively. The RSDs for migration time and peak area obtained from ten consecutive injections were less than 2% and recoveries varied from 97 to 102%. The method was applied to 23 samples of inexpensive Brazilian wines, showing wide compositional variation.