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At least 217 records · Page 12Linked to original sources
PubMed2006

Fluorophenol oxidation by a fungal chloroperoxidase.

Caldariomyces fumago chloroperoxidase degrades monofluorophenols at both pH 3 and pH 6. 4-Fluorophenol is most readily degraded and its oxidation is most efficient at pH 6. GC-MS analyses of the reaction products revealed compounds relating to the reaction of fluorophenol radical. The degradation of fluorinated compounds is of significant environmental interest and this versatile enzyme may by employed to treat contaminated soil or water prior to discharge.

Ascomycota↗
PubMed1999

Substituent effect of a fluorine atom on the mutagenicity of nitroquinolines.

Some 16 nitroquinolines (NQs) and their fluorinated derivatives were tested for mutagenicity in Salmonella typhimurium TA100 without S9 mix to investigate the effect of fluorine-substitution on the mutagenicity. These NQs consist of 5-NQs, 5-nitroquinoline N-oxides (5-NQOs), N-methyl-5-nitroquinolinium methanesulfonates (N-Me-5-NQs) and 8-NQs, including three ortho-F-NQs, one meta-F-NQ, four para-F-NQs and four 3-F-NQs. For this purpose, eight F-NQs were newly synthesized. The data indicated that the ratio of the mutagenic activities (revertants/plate/nmol) of fluorinated NQs to those of the corresponding parent non-fluorinated compounds ranged from 0.6- to 119-fold. The fluorine atom located para to the nitro group markedly enhanced the mutagenicity (24-fold and more), while three ortho-fluorinated derivatives showed no significant increase in mutagenicity (enhancement ratio were 0.6, 0.8 and 1.7). With respect to 8-NQs, its meta-fluorinated derivative also had an enhanced mutagenicity over the parent compound (53-fold). In addition, although N-Me-5-NQ was less mutagenic than 5-NQ and 5-NQO, the mutagenicity of N-Me-5-NQ was most significantly enhanced by fluorine-substitution. These results suggest that introduction of a fluorine atom to the molecule in question may be a useful tool to modify their mutagenic potency and to better understand the mechanism of mutation.

Chromatography, Gel↗
PubMed2006

The strength of weak interactions: aromatic fluorine in drug design.

Selective aromatic fluorine substitution can increase the affinity of a molecule for a macromolecular recognition site through non-covalent interactions. These effects are evaluated most accurately by direct comparison of binding affinities of selectively fluorinated compounds with their corresponding hydrocarbons. In cases where structural data confirm similar binding geometries for the fluorocarbon and hydrocarbon analogues, reliable estimates for the impact of fluorination upon arene-pi...X and C-F...X interaction energies are possible. Existing studies show that fluorination's impact on any individual molecular interaction is quite modest. Upon binding to a protein receptor, cumulative fluorinated aromatic quadrupolar and C-F...X dipolar interaction energies rarely differ from those the corresponding hydrocarbons by more than 1.3 kcal/mol, and most individual interactions appear to be in the 0.1-0.4 kcal/mol range. Similarly, non-ideal selective fluorination is rarely associated with a dramatic decrease in affinity, because the impact of weak repulsive interactions in the bound state is counterbalanced by increased lipophilicity.

Animals↗
PubMed2003

Volcanogenic fluorine in rainwater around active degassing volcanoes: Mt. Etna and Stromboli Island, Italy.

Many studies have assessed the strong influence of volcanic activity on the surrounding environment. This is particularly true for strong gas emitters such as Mt. Etna and Stromboli volcanoes. Among volcanic gases, fluorine compounds are potentially very harmful. Fluorine cycling through rainwater in the above volcanic areas was studied analysing more than 400 monthly bulk samples. Data indicate that only approximately 1% of fluorine emission through the plume is deposited on the two volcanic areas by meteoric precipitations. Although measured bulk rainwater fluorine fluxes are comparable to and sometimes higher than in heavily polluted areas, their influence on the surrounding vegetation is limited. Only annual crops, in fact, show some damage that could be an effect of fluorine deposition, indicating that long-living endemic plant species or varieties have developed some kind of resistance.

Air Pollutants↗
PubMed2003

Synthesis and structure-activity relationships of 5-amino-6-fluoro-1-[(1R,2S)-2-fluorocyclopropan-1-yl]-8-methylquinolonecarboxylic acid antibacterials having fluorinated 7-[(3R)-3-(1-aminocyclopropan-1-yl)pyrrolidin-1-yl] substituents.

A series of novel 5-amino-6-fluoro-1-[(1R,2S)-2-fluorocyclopropan-1-yl]-8-methylquinolones bearing fluorinated (3R)-3-(1-aminocyclopropan-1-yl)pyrrolidin-1-yl substituents at the C-7 position (2-4) was synthesized to obtain potent drugs for infections caused by Gram-positive pathogens, which include resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA), penicillin-resistant Streptococcus pneumoniae (PRSP), and vancomycin-resistant enterococci (VRE). These fluorinated compounds 2-4 exhibited potent antibacterial activity comparable with that of a compound bearing a non-fluorinated (3R)-3-(1-aminocyclopropan-1-yl)pyrrolidine moiety at the C-7 position (1) and had at least 4 times more potent activity against representative Gram-positive bacteria than ciprofloxacin (CPFX), gatifloxacin (GFLX), or moxifloxacin (MFLX). Among them, the 7-[(3S,4R)-4-(1-aminocyclopropan-1-yl)-3-fluoropyrrolidin-1-yl] derivative 3 (=DQ-113), which showed favorable profiles in preliminary toxicological and nonclinical pharmcokinetic studies, exhibited potent antibacterial activity against clinically isolated resistant Gram-positive pathogens.

Anti-Bacterial Agents↗
PubMed2000

[Preparation and use of chemical disinfectants in biological protection and prevention of contagious diseases : ecological aspects].

Ecological requirements to reduce negative effects of chemical disinfectants were one on major determinants the line of works to develop and introduce novel compounds that are environmentally safe hydrogen peroxide derivatives. The paper analyzes the possible routes of entering different fluorine compounds into the environment when disinfecting measures are made at therapeutical-and-preventive institutions, when emergencies occur at microbiological synthesis plants. The maximum concentration of a chemical that has no effect on biochemical processes when it is continuously used at sewage works is chosen as a safe (permissible) level. Preliminary calculations show that the use of PFK for disinfection will not pollute the environment with fluorides.

Anti-Infective Agents, Local↗
PubMed2006

Synthetic applications of beta-fluoroalkylated alpha,beta-unsaturated carbonyl compounds.

Beta-fluoroalkylated alpha,beta-unsaturated carbonyl compounds constitute efficient building blocks for the synthesis of complex fluorinated compounds. As the fluorinated moiety generally increases their reactivity, it also brings important modifications which can change the chemical behavior and selectivity. Their use has been already largely demonstrated. Nevertheless, the synthetic potential has not yet been fully explored and, consequently should play an important role in the design of new sophisticated fluorinated molecules. Nevertheless, it shall be important to develop new synthetic methods to enlarge their availability and their diversity.

Journal Article↗
PubMed2000

The H(2)(18)O solvent-induced isotope shift in (19)F NMR.

The H(2)(16)O/H(2)(18)O solvent-induced isotope shifts ((18)O SIIS) of the (19)F NMR signals of a number of fluorine compounds have been measured. These isotope shifts are observed to be upfield, downfield, or zero, depending on the specific compound and the precise solution conditions. At 25 degrees C and with an (18)O enrichment of 86%, the (18)O SIIS of several fluorinated amino acids were in the range of 0.0014-0.0018 ppm downfield. 5-Fluorouridine displays a significantly wider range of (18)O SIIS values. A 5-fluorouridine-labeled 16-mer RNA also displayed observable (18)O SIIS values, but the characteristics of these were significantly modified from those of free 5-fluorouridine. The experimental observations are consistent with the (18)O SIIS being composed of upfield and downfield components, with the relative contributions of these determining the size and direction of the overall isotope shift. This is discussed in terms of a combination of van der Waals interactions between the fluorine atom and the solvent, electrical and hydrogen bonding effects, and the perturbations to these due to (18)O substitution in the solvent water. This isotope effect promises to be a highly useful tool in a range of (19)F NMR studies.

Animals↗
PubMed1992

[Assessment of total mutagenic activity of harmful factors of the industrial environment at the metallurgy plants of South Ural].

Harmful factors of the industrial environment of the steel plants are represented by sulfur- and arsenic-containing compounds, nitrogen and carbon oxides, aerosols of heavy and rare metals, fluorine compounds whose concentrations exceed the maximum allowable ones in the air of the working place. The results of the cytogenetic examination of metallurgists attest to the pronounced total mutagenic activity of unfavourable factors of the industrial environment, among which the key role is played by arsenic, fluorine and heavy metal compounds.

Adult↗
PubMed2002

In vitro phototoxic properties of new 6-desfluoro and 6-fluoro-8-methylquinolones.

A representative set of potent antibacterial 6-desfluoro-8-methylquinolones, in which the C-6 fluorine atom is replaced by -NH(2) or -H, and their 6-fluoro counterparts, were investigated to evaluate their phototoxic potential and to explore the mechanism behind their phototoxicity. The capacity to photosensitize biological substrates (lipids, proteins, DNA) has been analyzed, as well as their photocytotoxicity on red blood cells and 3T3 murine fibroblasts. The results obtained show that the quinolones studied are able to photosensitize red blood cell lysis in an oxygen-dependent way and induce a high decrease in cell viability after UVA irradiation. A major correlation with phototoxicity lies in the structure of the individual antibacterials and their hydrophobicity; in particular, 6-amino derivatives are less phototoxic than corresponding unsubstituted and fluorinated compounds. Cellular phototoxicity was inhibited by the addition of free radical and hydroxyl radical scavengers (BHA, GSH and DMTU), suggesting the involvement of a radical mechanism in their cytotoxicity. A good correlation was observed between lipid peroxidation and phototoxicity, indicating that the test compounds exert their toxic effects mainly in the cellular membrane. Preliminary experiments on pBR322 DNA show that these derivatives do not photocleave DNA, differently from the two photogenotoxic fluoroquinolones, ciprofloxacin and lomefloxacin, used as reference compounds.

Animals↗
PubMed2001

Keeping Mars warm with new super greenhouse gases.

Our selection of new super greenhouse gases to fill a putative "window" in a future Martian atmosphere relies on quantum-mechanical calculations. Our study indicates that if Mars could somehow acquire an Earth-like atmospheric composition and surface pressure, then an Earth-like temperature could be sustained by a mixture of five to seven fluorine compounds. Martian mining requirements for replenishing the fluorine could be comparable to current terrestrial extraction.

Journal Article↗