A wide variety of aromatic compounds are enzymatically reduced to form anion free radicals that generally contain one more electron than their parent compounds. In general, the electron donor is any of a wide variety of flavoenzymes. Once formed, these anion free radicals reduce molecular oxygen to superoxide and regenerate the parent compound unchanged. The net reaction is the oxidation of the...

The lethal effect of oxygen on Escherichia coli organisms freeze-dried from water may be partly abolished by the addition of certain compounds before lyophilization. Three groups of such protective compounds were found: (i) thiourea, some of its derivatives and analogues; (ii) sugars, especially monosaccharides and some of their derivatives; (iii) some simple inorganic salts. The protective act...

Eight novel compounds were prepared by reaction of 5-(bromo- propoxyphenyl)-10,15,20-triphenylporphyrin with oxazole thiols, 1,3,4-oxadiazole thiols and 1,3,4-thiadiazole thiols, and their structures confirmed by UV-vis, IR, 1H-NMR, MS and elemental analysis. The assessment of indirectly measured 1O(2) production rates against 5,10,15,20-tetraphenyl porphyrin (H(2)TPP) were described and the re...

A number of N-phenyl-1,4-naphthoquinone monoimines 6-10 were prepared by on-water oxidative phenylamination of 1,5-dihydroxynaphthalene (1) and 5-acetylamino-1-hydroxynaphthalene (5) with oxygen-substituted phenylamines under aerobic conditions and either solar or green LED radiation, in the presence of rose bengal as singlet oxygen sensitizer. As compared to the conventional oxidative phenylam...

Objectives: During exposure to both biotic and abiotic stress, molecular oxygen can undergo reactions that result in the formation of reactive oxygen intermediates (ROIs) including singlet oxygen and highly reactive oxygen compounds such as hydrogen peroxide. ROIs and hydrogen peroxide are highly destructive to lipids, nucleic acids, and proteins. Collectively, the injury resulting from these r...

Time-dependent photoluminescence (PL) enhancement, blue shift, and photobleach were observed from the thiol-capped CdTe quantum dots (QDs) ingested in mouse myoblast cells and human primary liver cancer cells. It was revealed that the PL blue shift resulted from the photooxidation of the QD core by singlet oxygen molecules formed on the QD core surface.

H2S production has been proposed as a mechanism to explain bacterial resistance to antibiotics. In this work, we present evidence for the role of the cysJIH operon in resistance to ciprofloxacin mediated by H2S production with different sulfate as the only sulfur source. We found that the products of the cysJIH operon are involved in ciprofloxacin resistance by increasing both, the levels of H2...

Transition metal compounds are well documented to have diverse applications such as in catalysis, light-emitting materials and therapeutics. In the areas of photocatalysis and photodynamic therapy, metal compounds of heavy transition metals are highly sought after because they can give rise to triplet excited states upon photoexcitation. The long lifetimes (more than 1 μs) of the triplet states...