Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.17 (PCE)
 1,301 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The conditions that support the simultaneous activity of hydroxyl radicals (OH.) and heterotrophic aerobic bacterial metabolism were investigated using two probe compounds: (1) tetrachloroethene (PCE) for the detection of OH. generated by an iron-nitrilotriacetic acid (Fe-NTA) catalyzed Fenton-like reaction and (2) oxalate (OA) for the detection of heterotrophic metabolism of Xanthobacter flavus. In the absence of the bacterium in the quasi-steady-state Fenton's system, only PCE oxidation was observed; conversely, only OA assimilation was found in non-Fenton's systems containing X. flavus. In combined Fenton's-microbial systems, loss of both probes was observed. PCE oxidation increased and heterotrophic assimilation of OA declined as a function of an increase in the quasi-steady-state H2O2 concentration. Central composite rotatable experimental designs were used to determine the conditions that provide maximum simultaneous abiotic-biotic oxidations, which were achieved with a biomass level of 10(9) CFU/mL, 4.5 mM H2O2, and 2.5 mM Fe-NTA. These results demonstrate that heterotrophic bacterial metabolism can occur in the presence of hydroxyl radicals. Such simultaneous abiotic-biotic oxidations may exist when H2O2 is injected into the subsurface as a microbial oxygen source or as a source of chemical oxidants. In addition, hybrid abiotic-biotic systems could be used for the treatment of waters containing biorefractory organic contaminants present in recycle water, cooling water, or industrial waste streams.
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PMID:Evidence for simultaneous abiotic-biotic oxidations in a microbial-Fenton's system. 1147 49

The ability of modified Fenton reactions to promote simultaneous chemical and biological oxidation in an artificially contaminated soil was studied in batch laboratory slurry reactors. Tetrachloroethene (PCE) and oxalate (OA) were used to distinguish chemical oxidation from aerobic heterotrophic metabolism. PCE was mineralized by Fenton reactions, but OA was not oxidized. Indigenous soil microorganisms did not degrade added PCE aerobically but readily assimilated OA. Fenton reactions were promoted at the natural soil pH (7.6) by adding H2O2 and Fe(III), with nitrilotriacetic acid (NTA) as a chelator, at a constant molar ratio of H2O2/Fe(III)/NTA of 50:1:1. The *OH-mediated mineralization of PCE was demonstrated by adding 2-propanol (an *OH scavenger), which inhibited PCE oxidation. In subsequent dosing studies, PCE oxidation served as an indicator of Fenton reactions, while OA assimilation, dissolved oxygen (DO) concentration, and heterotrophic plate counts were indicators of aerobic microbial activity. Increasing Fenton doses to 20 times that required to achieve 95% PCE oxidation only delayed OA assimilation by 500 min and reduced plate counts by 1.5 log units g(-1) soil. Results show that aerobic metabolism can coexist with Fenton oxidation in soils.
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PMID:Effect of Fenton reagent dose on coexisting chemical and microbial oxidation in soil. 1668 23

Phyllanthus niruri is a medicinal plant (commonly known as stone breaker) found in the tropics and other parts of the world. It is known for its capacity to block the formation of calcium oxalate crystals and kidney stone formation in urolithiasis. This plant has been used to treat hyperglycemia, hypertension, pain, and mild cases of malaria. We examined the geno-, cyto- and overall toxicity of P. niruri whole plant ethanolic extract. The extract was administered as a single dose of 30 or 300 mg/kg to laboratory rats by gavage, accompanied by negative (0.9% saline) and positive (10 mg/mL N-ethyl-N-nitrosourea) controls that were injected intramuscularly 48 h after extract administration. The ratio of polychromatic (PCE)/normochromatic erythrocytes (NCE) from femur bone marrow was scored for genotoxicity. Cytotoxicity was determined using descending concentrations (0.2-0.0125 g/mL) of the extract incubated with peripheral blood mononuclear cells. Lactate dehydrogenase release from damaged cells was determined and the CC(50) calculated. Subchronic administration of the extract at 30 or 300 mg/kg was done for 90 days to determine general toxicity. PCE:NCE (%) for the extract and negative control was 63, compared to 168 (positive control). The CC(50) was 26.3 mg/mL and hepato-renal toxicity after subchronic extract administration was nil. We conclude that ethanol extract of P. niruri is not cytotoxic or genotoxic, and is generally non-toxic on subchronic administration.
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PMID:Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae). 2229 Apr 70