Is asbestos still a problem in the world? A current review.

Asbestos has been used by automobile, construction, manufacturing, power, and chemical industries for many years due to its particular properties, i.e. high tensile strength, non-flammable, thermal and electrical resistance and stability, and chemical resistance.

Gamma irradiation of clove: level of trapped radicals and effects on bioactive composition.

Background: Food irradiation is a widely used technique for improving the safety and shelf life of foods, including most spices. However, growing concerns by consumers about this technique require further investigation on the effects of radiation, both on the safety of the food and on its organoleptic properties. In this work, cloves of diverse origins were submitted to different irradiation doses in a Co source.

Selenium-containing chrysin and quercetin derivatives: attractive scaffolds for cancer therapy.

Selenium-containing chrysin (SeChry) and 3,7,3',4'-tetramethylquercetin (SePQue) derivatives were synthesized by a microwave-based methodology. In addition to their improvement in terms of DPPH scavenging and potential GPx-like activities, when tested in a panel of cancer cell lines both selenium-derivatives revealed consistently to be more cytotoxic when compared with their oxo and thio-analogues, evidencing the key role of selenocabonyl moiety for these activities. In particular, SeChry elicited a noteworthy cytotoxic activity with mean IC50 values 18- and 3-fold lower than those observed for chrysin and cisplatin, respectively.

Demethylation of theophylline (1,3-dimethylxanthine) to 1-methylxanthine: the first step of an antioxidising cascade.

The reaction of theophylline with HO(*) radical, produced by photolytic methods at pH 7, was studied in aqueous solution and the products characterised by HPLC and GC-MS. In addition to the expected 1,3-dimethyluric acid, the formation of 1-methylxanthine and, to a lesser extent, of 3-methylxanthine was observed. Theoretical calculations confirmed the preferred formation of the former compound.

Scavenging activity of aminoantipyrines against hydroxyl radical.

The pyrazolone derivatives antipyrine and 4-(N,N-dimethyl)-aminoantipyrine (aminopyrine) have long been used as analgesic, antipyretic and anti-inflammatory drugs. However, in spite of its recognized therapeutic benefits, the use of pyrazolones has been associated with agranulocytosis. Though the oxidation of aminopyrine by neutrophil-generated hypochlorous acid (HOCl), leading to the formation of a cation radical, has been considered responsible for the potential bone marrow toxicity, the reaction mechanisms of pyrazolones against other reactive oxygen species (ROS) remains elusive.

Antioxidant mechanisms of Quercetin and Myricetin in the gas phase and in solution--a comparison and validation of semi-empirical methods.

Flavonoids have long been recognized for their general health-promoting properties, of which their antioxidant activity may play an important role. In this work we have studied the properties of two flavonols, quercetin and myricetin, using semi-empirical methods in order to validate the application of the recent Parametric Model 6 and to understand the fundamental difference between the two molecules. Their geometries have been optimized and important molecular properties have been calculated.

Structure and redox properties of radicals derived from one-electron oxidised methylxanthines.

The repair of the one electron oxidised form of a xanthine derivative by another xanthine derivative was studied by reacting aqueous binary mixtures of xanthine derivatives with sulphate radical anion (SO(4)( -)) and following the concentration of both compounds as a function of time. The relative behaviour observed enabled the establishment of a qualitative order of antioxidant capacities for the several xanthines studied in acidic and neutral media. The same order was confirmed quantitatively by measuring the reduction potentials of the xanthines by cyclic voltammetry.

Dipyrone and aminopyrine are effective scavengers of reactive nitrogen species.

Reactive nitrogen species (RNS), namely nitric oxide (NO*) and peroxynitrite (ONOO-) are produced in the inflammatory sites and may contribute to the deleterious effects of inflammation. The aim of the present study was to evaluate the putative scavenging effect of a particular group of non-steroidal anti-inflammatory drugs (NSAIDs), the pyrazolone derivatives dipyrone, aminopyrine, isopropylantipyrine, and antipyrine against RNS, using in vitro non-cellular screening systems. The results obtained showed that dipyrone and aminopyrine were highly potent scavengers of NO* and ONOO- while antipyrine exerted little effect and isopropylantipyrine no effect whatsoever against these two RNS and that, in the presence of bicarbonate, the scavenging potencies of both dipyrone and aminopyrine were slightly decreased.

Transient spectroscopy of ninhydrin.

The photochemistry of ninhydrin in benzene and water was studied by laser flash photolysis and electron paramagnetic resonance. Its photochemistry was shown to be dependent on the solvent. In benzene, a triplet excited state was observed, which underwent hydrogen abstraction reactions or reduction to the radical anion.

Antioxidant properties of trans-epsilon-viniferin as compared to stilbene derivatives in aqueous and nonaqueous media.

trans-Epsilon-viniferin, the dimer of resveratrol, extracted from Vitis vinifera, has been evaluated for its antioxidant capacity. Its properties have been compared to those of resveratrol and synthetic stilbenic derivatives (4-hydroxystilbene, 4,4'-dihydroxystilbene, 3,5-dihydroxystilbene, and trimethylresveratrol), in regard to their liposolubility using two media with different polarity. The bleaching of beta-carotene by lipoperoxyl (LOO.