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PubMed1998

Structure-activity relationship of fluoroquinolone in Escherichia coli.

Structure-activity relationship of 20 fluoroquinolones was studied using the susceptible and 4 resistant Escherichia coli which were developed against 4 fluoroquinolones [ciprofloxacin (1), KR-10755 (6), norfloxacin (2), and ofloxacin (3)] in our laboratory. The C-7 and C-8 substituents of fluoroquinolone were important in various functions such as the inhibitory activity on DNA gyrase, permeability, and efflux. Among 20 fluoroquinolones, compounds with a 3-methyl-3,7-diazabicyclo[3.3.0]octan-1(5)-ene-7-yl substituent at the C-7 position or a chlorine substituent at the C-8 position showed a good inhibitory activity on DNA gyrase (especially a mutated DNA gyrase). Compounds with a 3,7-diazabicyclo [3.3.0]octan-1(5)-ene-7-yl substituent at the C-7 position showed good permeability in the susceptible and resistant strains, while compounds with a fluorine substituent at the C-8 position were less effluxed from cells.

Anti-Infective Agents↗
PubMed2005

Microcosm evaluation of the toxicity and risk to aquatic macrophytes from perfluorooctane sulfonic acid.

Perfluorooctane sulfonic acid (PFOS) is an anthropogenic contaminant detected in various environmental and biologic matrices. This compound is a fluorinated surfactant, a class of molecules renowned for their persistence and their global distribution but for which few ecotoxicological data are currently available, especially under field conditions. The toxicity of PFOS to the aquatic macrophytes Myriophyllum sibiricum and M. spicatum was investigated using 12,000 L outdoor microcosms. Replicate microcosms (n = 3) were treated with 0.3, 3, 10, and 30 mg/L PFOS as the potassium salt and assessed at regular intervals during a period of 42 days. M. sibiricum was more sensitive to PFOS under these simulated field conditions than M. spicatum. Toxicity was observed in the evaluated end points at > 3 mg/L PFOS for EC10s and > 12 mg/L PFOS for EC50s for M. spicatum and in M. sibiricum at > 0.1 mg/L PFOS for EC10s and > 1.6 mg/L PFOS for EC50s. The no observed-effect concentration (NOEC) for M. spicatum was consistently > or = 11.4 mg/L PFOS, whereas the NOEC for M. sibiricum was > or = 0.3 mg/L PFOS. A risk assessment for these plants estimated a negligible probability of toxicity being observed in these plants from PFOS exposure at current environmental concentrations.

Alkanesulfonic Acids↗
PubMed2005

Microcosm evaluation of the fate, toxicity, and risk to aquatic macrophytes from perfluorooctanoic acid (PFOA).

Perfluorooctanoic acid (PFOA) is an anthropogenic contaminant detected in various environmental and biological matrices. This compound is a fluorinated surfactant, belonging to a class of molecules known for persistence and their global distribution, but for which little ecotoxicological data are currently available, especially under field conditions. The environmental fate and toxicity of PFOA to the aquatic macrophytes Myriophyllum sibiricum and M. spicatum were investigated using 12,000 L outdoor microcosms. Replicate microcosms (n = 3) were treated with 0.3, 1, 30, and 100 mg/L PFOA as the sodium salt, plus controls, and assessed at regular intervals over 35 days. PFOA showed no significant dissipation from the water column, except at the greatest concentration, where partitioning from the water column into other compartments is suspected. The two species of Myriophyllum were similar in their sensitivity to PFOA under these simulated field conditions. Toxicity after 14 to 35 days of exposure in the evaluated endpoints for M. spicatum was > or = 5.7 mg/L PFOA for EC10s and > or = 31.8 mg/L PFOA for EC50s and in M. sibiricum was > or = 8.4 mg/L PFOA for EC10s and > or = 35.8 mg/L PFOA for EC50s. The no observed effects concentrations (NOECs) for Myriophyllum spp. were consistently > or = 23.9 mg/L PFOA. A risk assessment for these plant species estimated a negligible probability of toxicity being observed from PFOA exposure at current environmental concentrations.

Caprylates↗
PubMed1983

A biochemical study of the reconstitution of D-lactate dehydrogenase-deficient membrane vesicles using fluorine-labeled components.

Fluorine-19 labeled compounds have been incorporated into lipids and proteins of Escherichia coli. 19F-Labeled membrane vesicles, prepared by growing a fatty acid auxotroph of a D-lactate dehydrogenase-deficient strain on 8,8-difluoromyristic acid, can be reconstituted for oxidase and transport activities by binding exogenous D-lactate dehydrogenase. 19F-Labeled D-lactate dehydrogenases prepared by addition of fluorotryptophans to a tryptophan-requiring strain are able to reconstitute D-lactate dehydrogenase-deficient membrane vesicles. Thus, lipid and protein can be labeled independently and used to investigate protein-lipid interactions in membranes.

Cell Membrane↗
PubMed1985

Studies on the mutagenicity and tumor-initiating activity of methylated fluorenes.

Several methylated analogs of fluorene were evaluated as mutagens in Salmonella typhimurium TA98 and TA100 in the presence and absence of microsomal activation. Among the methylated derivatives of fluorene assayed were 9-methylfluorene, 2-fluoro- and 2,7-difluoro-9-methylfluorene, 1,9-, 2,9-, 3,9- and 4,9-dimethylfluorene, 2,3,9-trimethylfluorene and 2,7,9-trimethylfluorene. Mutagenic activity was observed for several of these fluorene derivatives in the presence of rat liver homogenate. The data support a previous observation that a single methyl substituent in the 9-position of fluorene is associated with mutagenic activity within this series of compounds. Substitution with fluorine at both the 2- and 7-positions of 9-methylfluorene was not associated with a loss of mutagenic activity as evidenced by the similar mutagenic activity of 2,7-difluoro-9-methylfluorene and 9-methylfluorene. However, 2,7,9-trimethylfluorene was not mutagenic under these assay conditions. 9-Methylfluorene, 1,9-, 2,9-, 3,9- and 4,9-dimethylfluorene and 2,3,9-trimethylfluorene were active as mutagens in the presence of rat liver homogenate, but were inactive as tumor initiators when assayed on mouse skin.

Animals↗
PubMed2006

Mild hydrolysis of 2-trifluoromethylphenol: kinetics, mechanism and environmental relevance.

2-Trifluoromethylphenol was hydrolysed in a phosphate buffer at neutral pH. At mild temperatures ranging from 34 degrees C to 69 degrees C this compound liberates consecutively fluorine anions to form salicylic acid. This process is energetically driven by the hydration of the fluorine anions. No intermediates have been detected by HPLC and (19)F-NMR and this was confirmed by computer calculations which favor the first step in the whole reaction sequence being rate-limiting. Accordingly, the reaction energy of the first dehalogenation of the trifluoromethyl anion is 28.4 kcal mol(-1) higher than for the second dehalogenation. The pseudo-first-order kinetic was determined and from an Arrhenius diagram an activation energy of E(a)=25.1 kcal mol(-1) has been estimated. At 37 degrees C and a pH of 7.4 the half-life was 6.9 h. The rate of hydrolysis was favored at higher pH and it was not influenced by oxygen, sunlight or trace elements found in natural water. The latter was shown by incubations with lake water instead of distilled water.

Anions↗
PubMed2000

Radiosynthesis of [18F]Lu29-024: a potential PET ligand for brain imaging of the serotonergic 5-HT2 receptor.

In a previous work, Lu29-024 (2,5-dimethyl-3-(4-fluorophenyl)-1-(1-methyl-4-piperidinyl)-1H-indole), a selective 5-HT2A receptor antagonist with nanomolar affinity and high selectivity, was labeled with carbon-11 to evaluate its behavior as a potential PET ligand for the serotonergic 5-HT2A receptor in the central nervous system. Administration of this tracer to rats was followed by a good brain uptake, no brain labeled metabolites but no specific, regio-selective, binding at 20 and 40 min post injection. Despite this, the data noted at 20 and 40 min suggest that this tracer, if associated with a radioactive emitter with a longer half-life than that of carbon-11, could be useful for the quantification of 5HT2A receptors. For these reasons, we chose to label this compound, bearing a fluorine atom, with [18F]fluoride, in order to perform rat studies over a more prolonged time-scale. The precursor for the radiosynthesis of [18F]Lu29-024 was obtained in an overall yield of 20% by a multi-step synthesis including an acetonylation reaction followed by a Fisher indole reaction. The radiotracer was prepared by an aromatic substitution with activated [18F]fluoride followed by a decarbonylation reaction that employed Wilkinson's catalyst. The radiosynthesis of [18F]Lu29-024 required approximatively 110 min with an overall radiochemical yield of 20-35% and specific activities of 37GBq/micromol. Fluorine-labeled Lu29-024 may thus be envisaged as a potentially useful PET tracer that can be applied to a wide range of neurological and psychiatric diseases.

Animals↗
PubMed1990

Synthesis and dopamine receptor affinities of 2-(4-fluoro-3- hydroxyphenyl)ethylamine and N-substituted derivatives.

The synthesis of 2-(4-fluoro-3-hydroxyphenyl)ethylamine (26) and of some N,N-dialkyl derivatives (27-30) starting from 4-fluoro-3-hydroxytoluene and their in vitro binding affinities for dopamine (DA) receptor are reported. The amine 26 can be regarded as a molecular modification of DA in which the para hydroxyl group is replaced by fluorine. The new compounds 26-30 were evaluated for their affinity at D-1 and D-2 DA receptor subtypes by displacement of [3H]SCH 23390 (D-1 selective) and [3H]spiperone (D-2 selective). The amine 26 had about 2-fold less affinity for D-1 and D-2 binding sites than DA. The substitution of the amino group with ethyl, n-propyl, and 2-phenylethyl groups decreased the affinity for D-1 binding sites but greatly enhanced the effectiveness on D-2 binding sites. The N-ethyl- (28) and N-n-propyl-N-(2-phenylethyl)-2-(4-fluoro-3- hydroxyphenyl)ethylamine (30) were the most potent members of the series with high selectivity for D-2 binding sites. A similar effect was observed with isomeric N-n-propyl-N-(2-phenylethyl)-2-(3-fluoro-4-hydroxyphenyl)ethylamine (31) which was approximately 65 times more selective for D-2 sites vs D-1 sites. The introduction of a 2-phenylethyl group on the nitrogen atom induce the highest effect, perhaps as a consequence of an increased liposolubility or of binding to a complementary lipophilic site on the receptor.

Animals↗
PubMed2004

A facile photochemical surface modification technique for the generation of microstructured fluorinated surfaces.

We describe a simple photochemical process which allows fluoropolymers to be chemically bound at room temperature onto SiO2 surfaces. To achieve this, at first a benzophenone silane is used to form a self-assembled monolayer on the surface of the substrate, which is subsequently coated with the fluoropolymer and irradiated with UV light of wavelength 365 nm. Using this very simple approach, we have been able to create ultrahydrophobic surfaces with very low surface free energies together with a good degree of control in thickness and composition as well as strong adhesion to the monolayer. The use of a UV-based process to attach the films on SiO2 surfaces opens the door for photopatterning of surfaces with fluorinated and nonfluorinated compounds to yield well-defined microstructures with spatial control of the wetting properties of the substrates.

Journal Article↗
PubMed1992

Corneal toxicity study of two perfluorocarbon liquids in rabbit eyes.

Perfluorocarbon liquids are fully fluorinated, synthetic, transparent compounds with a high specific gravity. These compounds are being increasingly used as an intraoperative tool for repair of complicated retinal detachments. A potential complication of their use, however, is liquid entering the anterior chamber in aphakic patients. In the study described herein we evaluated the effects of two of these liquids when placed in the anterior chamber of the rabbit eye. Sixteen rabbit eyes underwent anterior chamber injection of 0.05 ml of either perfluoroctane, perfluoropolyether, or balanced salt solution (control eyes). Animals were monitored clinically by biomicroscopy and external photography for up to 14 days, after which they were sacrificed and the corneas processed for light and for scanning electron microscopy. The animals injected with perfluoropolyether showed more intense stromal inflammation and corneal vascularization (p less than 0.02) than did those that received perfluoroctane. However, the perfluoroctane group showed more of the "fish-egging" phenomenon (p less than 0.03). Loss of endothelial cells was similar in the two groups, as determined by light and scanning electron microscopy. These results suggest that the corneal toxicity of these two perfluorocarbon liquids is such that their use as vitreous substitutes should be limited to short-term replacement.

Animals↗
PubMed1983

Metabolism of Halophenols by 2,4,5-trichlorophenoxyacetic acid-degrading Pseudomonas cepacia.

Resting cells of 2,4,5-trichlorophenoxyacetic acid-grown Pseudomonas cepacia AC1100 were able to completely and rapidly dechlorinate several chlorine-substituted phenols, including 2,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol. Several other trichlorophenols were only partially dechlorinated. The evidence suggests that 2,4,5-trichlorophenol is an intermediate in the degradation of 2,4,5-trichlorophenoxyacetic acid by strain AC1100. Moreover, although strain AC1100 was isolated by selection for growth on a chlorinated aromatic compound, brominated and fluorinated analogs were efficiently dehalogenated by strain AC1100 resting cells, whereas an iodinated analog was poorly dehalogenated.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed2001

Fungal metabolism of toluene: monitoring of fluorinated analogs by (19)F nuclear magnetic resonance spectroscopy.

We used isomeric fluorotoluenes as model substrates to study the catabolism of toluene by five deuteromycete fungi and one ascomycete fungus capable of growth on toluene as the sole carbon and energy source, as well as by two fungi (Cunninghamella echinulata and Aspergillus niger) that cometabolize toluene. Whole cells were incubated with 2-, 3-, and 4-fluorotoluene, and metabolites were characterized by (19)F nuclear magnetic resonance. Oxidation of fluorotoluene by C. echinulata was initiated either at the aromatic ring, resulting in fluorinated o-cresol, or at the methyl group to form fluorobenzoate. The initial conversion of the fluorotoluenes by toluene-grown fungi occurred only at the side chain and resulted in fluorinated benzoates. The latter compounds were the substrate for the ring hydroxylation and, depending on the fluorine position, were further metabolized up to catecholic intermediates. From the (19)F nuclear magnetic resonance metabolic profiles, we propose that diverse fungi that grow on toluene assimilate toluene by an initial oxidation of the methyl group.

Biodegradation, Environmental↗
PubMed2001

Plasma, intestine and tumor levels of 5-fluorouracil in mice bearing L1210 ascites tumor following oral administration of 5-fluorouracil, UFT (mixed compound of tegafur and uracil), carmofur and 5'-deoxy-5-fluorouridine.

Several 5-fluorouracil (5-FU) derivatives, 1-hexylcarbamoyl-5-fluorouracil (HCFU), 5'-deoxy-5-fluorouridine (5'-DFUR) and UFT (mixed compound of tegafur and uracil), have been developed and clinically widely used. However, comparative pharmacokinetic studies of the parent compound and other fluorinated drivatives have not been precisely reported. The dosage of the oral clinical use for human cancer of 5-FU, HCFU, 5'-DFUR and UFT as tegafur (FT) is 200-300mg/d, 600mg/d, 800-1,200mg/d and 300-600mg/d respectively. These amounts of the drugs are almost equimolar. Previously, we reported the effect of oral equimolar administration of each four drugs on thymidilate synthase activity, deoxyribonucleotide metabolism and cell cycle progression in L1210 ascites tumor. (1,2) In this study, we examined the antitumor effect and 5-FU concentration in the plasma, intestine and tumor after oral equimolar administrations of each drug using BDF1 mice bearing L1210 ascites tumor. In our study, UFT showed the best life prolongation among these four drugs. The intestine 5-FU level was highest by treatment with 5-FU during the initial 4 h. The plasma 5-FU level was highest by treatment with HCFU for 4 h. But the tumor 5-FU level was highest by treatment with UFT over the 24 h. In spite of the high plasma 5-FU concentration after the treatment with HCFU, the 5-FU concentration in the tumor was below the detectable level until 24 h. These findings suggested that the highest specific accumulation of 5-FU in tumor cells may explain the best therapeutic results of UFT.

Administration, Oral↗
PubMed1997

Inhibitory effects of quassinoid derivatives on Epstein-Barr virus early antigen activation.

Short-term in vitro assays for tumor promoters and antitumor promoters (Epstein-Barr virus activation test) were carried out for semisynthetic quassinoids (3-7), which were obtained by esterification of the C-15 OH group of deacetylated isobrucein-B (2). All the ester derivatives showed higher antitumor promoting activity than that of the potent compound 2. A compound containing a fluorinated aliphatic ester showed the highest potency.

Antigens, Viral↗
PubMed2000

Clinical update of gemcitabine in pancreas cancer.

Pancreatic cancer constitutes less than 2% of all cancers diagnosed in Singapore, consistent with the proportion described worldwide. About 40% of patients are diagnosed when the disease is locally advanced but without metastases. Another 40% are diagnosed with distant metastases. Only 20% are diagnosed when resectable. Most are adenocarcinomas arising from the head of the pancreas. Systemic chemotherapy is used for advanced metastatic pancreatic cancer but has met with limited success. Gemcitabine is a new fluorine-substituted cytarabine compound. In a randomised study it appears to confer statistically significant, although modest, improvement in quality of life and survival of patients with metastatic pancreas cancer. Evaluation of the drug in combination chemotherapy regimens and with radiation continues.

Adenocarcinoma↗