Krzysztof Lichszteld

The effect of thymol and its derivatives on reactions generating reactive oxygen species.

The effects of thymol (TOH), thymoquinone (TQ) and dithymoquinone (TQ2) on the reactions generating reactive oxygen species (ROS) such as superoxide anion radical (O2*-), hydroxyl radical (HO*) and singlet oxygen (1O2) were tested using the chemiluminescence (CL) and spectrophotometry methods. All tested compounds acted as scavengers of various ROS. The rate constant of 1O2-dimols quenching by thymol was calculated.

The extra-weak chemiluminescence generated during oxidation of some tetracycline antibiotics II. Peroxidation

Chemiluminescence (CL) appearing during autoxidation of tetracycline (TC) antibiotics has been studied. The CL spectrum consists of four emission bands with maxima at 520, 585, 640 and 700 nm. The bands at 585, 640 and 700 nm are similar to those observed for singlet molecular oxygen (1O2). The effect of 1O2 quenchers and free radical reaction inhibitors on the light emission is also reported. The data support the concept that, during the autoxidation of TCs, cytotoxic oxygen species such as HO., O2.-, H2O2 and 1O2 are formed.

Formation of active oxygen species during autoxidation of DOPA

The light emission during DOPA autoxidation and the transition metal ion-catalyzed oxidation of this amine to melanins has been studied. Chemiluminescence and fluorescence spectra from both systems were measured. The light emission was inhibited by quenchers of singlet oxygen (1O2) and scavengers of superoxide anion radical (O 2−) hydroxyl radical (HO.) and by catalase. The generation of 1O2 was confirmed using electron spin resonance (ESR) and 2,2,6,6-tetramethylpiperidine as a trap as well as by spectrophotometry method. The formation of HO. was demonstrated by the technique of ESR spin trapping with DMPO as a spin trap.

The formation of singlet oxygen during oxidation of catechol amines as detected by infrared chemiluminescence and spectrophotometric method.

1Δg → 3∑g- near infrared chem iluminescence from the peroxidation reaction of dopa, dopamine, noradrenaline and adrenaline was measured. The spectrophotometric method based on the bleaching of p-nitrosodimethylaniline was applied to check the generation of singlet oxygen catecholamines.

Evidence for the Generation of Singlet Molecular Oxygen during Dopa and Dopamine Peroxidation

Abstract Participation of singlet molecular oxygen (1O2) in peroxidation of dopa and dopamine was studied by measurements of chemiluminescence spectra, the influence of solvents with various lifetime of O2 (1Δg) and O2 (1Δg)-quenchers on quantum yield of chemiluminescence. A decrease of absorption and fluorescence intensities of 1,3-diphenylizobenzofuran (DPBF) was also studied in the presence of dopa and dopamine oxidized with alkaline H2O2 as a criterion for the involvement of 1O2.

Singlet Molecular Oxygen in Formaldehyde Oxidation

Chemiluminescence (CL) appearing during oxidation of CH2O by H2O2 in 0.5 mM KOH has been studied. The CL spectrum contains a strong band lying in the near infrared, and two bands at 21000 cm-1 and 15800 cm-1, being characteristic of singlet molecular oxygen (102>. The effect of 102-quenchers and free-radical reaction inhibitors exerted on the light emission has also been studied. The obtained results indicate that one of the emitters is the 102.

Chemiluminescence accompanying oxidation of bopindolol.

The oxidation of bopindolol using the Co-ethylenediaminetetraacetic acid (EDTA) + H2O2 system was investigated by spectrophotometric, chemiluminescence, and fluorescence methods. The effects of oxygen free radicals scavengers and 1O2 quenchers on the light emission were measured. The obtained results show the electronically excited products of the bopindolol degradation are involved in the oxidation process.

Antioxidant action of several β‐adrenergic blockers and related compounds

The aim of the present study was to investigate the effect of several β‐adrenergic blockers and related compounds with respect to generation of reactive oxygen species, especially hydroxyl radicals. Measurements were done using a chemiluminescence technique and the Co(II)‐EDTA + H2O2 system as a source of active oxygen species.

Hydroxyl radical generation by redox cycling of some chemotherapeutic antibiotics

The anticancer drugs: adriamycin, farmorubicin and mitomycin C greatly enhance the generation of hydroxyl radicals (HO.) from H2O2 in the presence of Co(II) ions (CoCl2) at pH 7.4 and 8, as measured by the deoxyribose assay. Catalase, hydroxyl radical scavengers (mannitol, cysteine, glutathione, thiourea, lactic dehydrogenase) inhibited the degradation of deoxyribose confirming that HO‐radicals are responsible for the degradation of the carbohydrate.

Electron spin resonance and spectrophotometry investigation of singlet oxygen formation during tetracycline autoxidation

Abstract The generation of 1O21Δg during autoxidation of tetracyclines (tetracycline, oxytetracycline, chlortetracycline and methacycline) in the presence of Co(II) ions was studied using electron spin resonance (ESR) and spectrophotometry methods. 2,2,6,6-tetramethylpiperidine was used as a trap in the ESR study. The spectrophotometry determination of 1O2 was based on bleaching of p -nitrosodimethylaniline (RNO) caused by the product of the reaction of 1O2 with imidazole and was followed by monitoring the decrease in optical density at 440 nm. The effect of 1O2 quenchers on the concentration of nitroxide radicals and on the bleaching of RNO was studied.