Oxidative DNA damage induced by autoxidation of microquantities of S(iv) in the presence of Ni(ii)–Gly-Gly-His

A mitochondria-targeted near-infrared fluorescent probe for detection and imaging of HSO3- in living cells

Sulfur dioxide, an essential gas signaling molecule mainly produced in mitochondria, plays important roles in many physiological and pathological processes. Herein, a near-infrared fluorescent probe, A1, with good mitochondria targeting ability was developed for colorimetric and fluorescence detection of HSO₃^-. Probe A1 has a conjugated cyanine structure that can selectively react with HSO₃^- through the nucleophilic addition. The reaction with HSO₃^- destroys the conjugated structure of probe A1, resulting in fluorescence quenching, and accompaniedby color change of probe A1 solution from purple-red to colorless. Probe A1 showed high selectivity and good sensitivity to HSO₃^- in PBS. And the limit of detection was calculated to be 1.28 and 0.037 μM for colorimetry and fluorescence spectrophotometry respectively. In addition, probe A1 mainly entered the mitochondria in living cells, and was successfully used for imaging the exogenous/endogenous HSO₃^- in cells. These results suggest the potential applications of probe A1 in biological systems.

A ratiometric fluorescent probe for the rapid and specific detection of HSO3 - in water samples

Hydrosulphite (HSO₃ ^- ), as a common and important chemical reagent, is widely used in everyday life, however excessive use and abuse of HSO₃ ^- can cause potential harmful effects on the environment and in biological health. In this paper, we describe the design and preparation of a colorimetric and ratiometric fluorescence probe for the visual detection of HSO₃ ^- (excitation wavelengths were, respectively, 336 nm and 520 nm). This method showed some advantages including simple preparation, high selectivity, fast response, and significant colour and fluorescence ratio (F₄₅₀ /F₅₉₄ ) changes in the presence of HSO₃ ^- . In addition, this probe was used successfully for the detection of HSO₃ ^- in real water samples and showed a good recovery rate range.

A mitochondrion-targeted dual-site fluorescent probe for the discriminative detection of SO32− and HSO3− in living HepG-2 cells

Sulfur dioxide, known as an environmental pollutant, produced during industrial productions is also a common food additive that is permitted worldwide. In living organisms, sulfur dioxide forms hydrates of sulfite (SO₂·H₂O), bisulfite (HSO₃⁻) and sulfite (SO₃²⁻) under physiological pH conditions; these three exist in a dynamic balance and play a role in maintaining redox balance, further participating in a wide range of physiological and pathological processes. On the basis of the differences in nucleophilicity between SO₃²⁻ and HSO₃⁻, for the first time, we built a mitochondrion-targeted dual-site fluorescent probe (Mito-CDTH-CHO) based on benzopyran for the highly specific detection of SO₃²⁻ and HSO₃⁻ with two diverse emission channels. Mito-CDTH-CHO can discriminatively respond to the levels of HSO₃⁻ and SO₃²⁻. Besides, its advantages of low cytotoxicity, superior biocompatibility and excellent mitochondrial enrichment ability contribute to the detection and observation of the distribution of sulfur dioxide derivatives in living organisms as well as allowing further studies on the physiological functions of sulfur dioxide.

Rational design and sensing mechanism of a dual-site fluorescence probe for HSO₃⁻ and SO₃²⁻.

Study of DNA damage caused by dipyrone in presence of some transition metal ions

The DNA damage in the presence of dipyrone (used as its sodium salt, NaDip) and some transition metal ions in an air saturated ([O₂] ≈ 0.25 mM) non-buffered solution at T = (25.0 ± 0.5)°C was investigated by agarose gel electrophoresis. As metal ions Cu²⁺, Fe³⁺, Ni²⁺ and Mn³⁺ were selected and evaluated in the present study because of the important role they play in a biological system. pUC19 plasmid DNA damage-induced by NaDip (80-600 μM) was observed in the presence of 100 μM Cu²⁺. The damage was proportional to the NaDip concentration provided that the order of addition of reagents (pUC19 plasmid DNA + Cu²⁺ + NaDip) is obeyed. Addition in the reaction medium of ligands for Cu²⁺ and Cu⁺, respectively EDTA and neocuproine, promoted total inhibition or reduction of the pUC19 plasmid DNA damage suggesting the involvement of the Cu²⁺/Cu⁺ cycle. Besides, the decrease in the pUC19 plasmid DNA damage after addition of catalase (1.0 × 10^-4 mg μL^-1) in the same reaction medium indicates that H₂O₂ is also involved in the damage process. In NaDip concentration range (80-600 μM), and under same the experimental conditions, it was not possible to conclude whether there was pUC19 plasmid DNA damage caused by 10 μM Fe³⁺. No damage was observed in the presence of Mn³⁺ or Ni²⁺. Although the technique used in this study is sensitive to detect the pUC19 plasmid DNA damage it was not possible to identify in which DNA base this damage occurs. Further studies with other techniques should be made to unambiguously identify the oxidative intermediates that are responsible for the DNA damage. As far as we know, this is the first study dealing with the pUC19 plasmid DNA damage-induced by NaDip in presence of copper, iron, nickel and manganese ions.

Metal-mediated DNA damage and cell death: mechanisms, detection methods, and cellular consequences

Metal ions cause various types of DNA damage by multiple mechanisms, and this damage is a primary cause of cell death and disease.

Comparison of Transition Metal-Mediated Oxidation Reactions of Guanine in Nucleoside and Single-Stranded Oligodeoxynucleotide Contexts

As the most readily oxidized of DNA's four natural bases, guanine is a prime target for attack by reactive oxygen species (ROS) and transition metal-mediated oxidants. The oxidation products of a modified guanosine nucleoside and of a single-stranded oligodeoxynucleotide, 5'-d(TTTTTTTGTTTTTTT)-3' have been studied using oxidants that include Co(II), Ni(II), and Ir(IV) compounds as well as photochemically generated oxidants such as sulphate radical, electron-transfer agents (riboflavin) and singlet oxygen. The oxidized lesions formed include spiroiminodihydantoin (Sp), guanidinohydantoin (Gh), imidazolone (Iz), oxazolone (Z) and 5-carboxamido-5-formamido-2-iminohydantion (2-Ih) nucleosides with a high degree of dependence on the exact oxidation system employed. Interestingly, a nickel(II) macrocyclic complex in conjunction with KHSO(5) leads to the recently reported 2-Ih heterocycle as the major product in both the nucleoside and oligonucleotide contexts.

Rotating ring-disk voltammetric investigations on the degradation rate of the nickel(III)-glycylglycyl-L-histidine complex

The voltammetric behavior of the Ni(II)/glycylglycyl-L-histidine complex and the degradation of the electrogenerated Ni(III) species were investigated by cyclic voltammetry. Results of electrochemical and spectrophotometric experiments indicated some differences in the nature and reactivity of Ni(III) complexes formed by two independent routes, i.e., anodic oxidation of Ni(II) and homogeneous oxidation by an autocatalytic reaction in a medium containing oxygen and S(IV) (H2SO3, HSO[Formula: see text], and SO[Formula: see text]). The Ni(III) species formed electrochemically reacts in a fast chemical process (EC mechanism) and the observed rate constant of the degradation (k = 0.17 s–1) was determined by a rotating ring-disk electrode technique measuring kinetic collection efficiency values as a function of the rotation rate. Key words: nickel, glycylglycyl-L-histidine, sulfite, degradation reaction, rotating ring-disk voltammetry.

DNA damage and 2′-deoxyguanosine oxidation induced by S(IV) autoxidation catalyzed by copper(II) tetraglycine complexes: Synergistic effect of a second metal ion

S(IV) (SO(2),HSO(3)(-)andSO(3)(2-)) autoxidation catalyzed by Cu(II)/tetraglycine complexes in the presence of DNA or 2'-deoxyguanosine (dGuo) resulted in DNA strand breaks and formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), respectively. Ni(II), Co(II) or Mn(II) (1.0x10(-4)M) complexes had much smaller effects. Cu(II)/tetraglycine (1.0x10(-4)M) in the presence of Ni(II) or Mn(II) (10(-7)-10(-6)M) and S(IV) showed remarkable synergistic effect with these metal ions producing a higher yield of 8-oxodGuo. Oxidation of dGuo and DNA damage were attributed to oxysulfur radicals formed as intermediates in S(IV) autoxidation catalyzed by transition metal ions. SO*(3)(-) and HO* radicals were detected by EPR-spin trapping experiments with DMPO (5,5-dimethyl-1-pyrroline-N-oxide).