Aqueous Photolysis of Niclosamide

Graebing, Phillip W.; Chib, J. S.; Hubert, Terrance D.; Gingerich, William H.

doi:10.1021/jf030520o

Cited by 20 publications

(34 citation statements)

References 21 publications

(25 reference statements)

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“…A polar peak at 3.7 min was apparent in individual sampling points of soils of 1.5-mm and less depths. This peak is similar to degradates reported in the aqueous photolysis of niclosamide in pH 9 buffer (15). In that study a 3-min peak was discovered to be made up of carbon dioxide and several organic acids, indicating complete breakdown of the aromatic ring system.…”

Section: Light Transmittance In Relation To Soil Depthsupporting

confidence: 84%

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Frank¹,

Graebing²,

Chib³

2002

J. Agric. Food Chem.

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The effects of soil depth and moisture on pesticide photolysis were studied. Moist soil at depths of 3, 2.5, 2, 1.5, 1, and 0.5 mm were each dosed at 2.5 microg/g with (14)C-niclosamide and photolyzed under a xenon lamp at constant temperature. Samples were removed after 20, 40, 110, and 153 h of continuous irradiation. The decrease in percent of niclosamide and the appearance of degradates were followed by analyzing the soil extracts by HPLC. A corresponding set of experiments used air-dried soil. An experiment was also performed using initially moist soil which was permitted to dry during photolysis but returned to moist conditions at each sampling. Qualitative and quantitative differences were found in the rate and route of degradation of niclosamide under these conditions. These differences have resulted from a combination of reduced photochemical activity and microbial population in dry soil. The half-lives of niclosamide in the dry soils were 2 to 5 times longer than those in the moisture-maintained soil. There was also a noticeable difference in the half-lives in soil of different depths. Moisture-maintained soil showed a uniform linear increase in half-life from 95 to 195 h as soil depth increased from 0.5 mm to 3.0 mm. With air-dried soil the half-lives were greatly dependent on soil depth, showing a much broader range of 199 h at 0.5-mm to 1064 h in 3.0-mm soil. An experimental design is described which maintains soil temperature and moisture to preset conditions.

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Section: Light Transmittance In Relation To Soil Depthsupporting

confidence: 84%

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Frank¹,

Graebing²,

Chib³

2002

J. Agric. Food Chem.

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“…2-C-4-NA is also reported as a photolysis product of niclosamide [4]. Espinosa-Aquirre et al [5] reported the metabolism of niclosamide, which is used as an anti-helminthic drug, results in the formation of 2-C-4-NA and 5-chlorosalicylic acid metabolites by hydrolytic cleavage of amide bond.…”

Section: Introductionmentioning

confidence: 99%

Metabolism of 2-Chloro-4-Nitroaniline via Novel Aerobic Degradation Pathway by Rhodococcus sp. Strain MB-P1

et al. 2013

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2-chloro-4-nitroaniline (2-C-4-NA) is used as an intermediate in the manufacture of dyes, pharmaceuticals, corrosion inhibitor and also used in the synthesis of niclosamide, a molluscicide. It is marked as a black-listed substance due to its poor biodegradability. We report biodegradation of 2-C-4-NA and its pathway characterization by Rhodococcus sp. strain MB-P1 under aerobic conditions. The strain MB-P1 utilizes 2-C-4-NA as the sole carbon, nitrogen, and energy source. In the growth medium, the degradation of 2-C-4-NA occurs with the release of nitrite ions, chloride ions, and ammonia. During the resting cell studies, the 2-C-4-NA-induced cells of strain MB-P1 transformed 2-C-4-NA stoichiometrically to 4-amino-3-chlorophenol (4-A-3-CP), which subsequently gets transformed to 6-chlorohydroxyquinol (6-CHQ) metabolite. Enzyme assays by cell-free lysates prepared from 2-C-4-NA-induced MB-P1 cells, demonstrated that the first enzyme in the 2-C-4-NA degradation pathway is a flavin-dependent monooxygenase that catalyzes the stoichiometric removal of nitro group and production of 4-A-3-CP. Oxygen uptake studies on 4-A-3-CP and related anilines by 2-C-4-NA-induced MB-P1 cells demonstrated the involvement of aniline dioxygenase in the second step of 2-C-4-NA degradation. This is the first report showing 2-C-4-NA degradation and elucidation of corresponding metabolic pathway by an aerobic bacterium.

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“…The polar materials formed in both aquatic studies are very similar in nature to polar degradates observed in the aqueous photolysis of niclosamide (15). Niclosamide was found to be completely photolyzed in pH 9 buffer into carbon dioxide and five or six aliphatic acids.…”

Section: Discussionmentioning

confidence: 52%

Metabolism of Niclosamide in Sediment and Water Systems

Graebing¹,

Chib²,

Hubert³

et al. 2004

J. Agric. Food Chem.

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A series of experiments analyzed the kinetics and mechanisms of [(14)C]niclosamide degradation. The aerobic aquatic metabolism of [(14)C]niclosamide was studied in nonsterile river water/sediment mixtures. Test systems, maintained under aerobic conditions, were treated with niclosamide and incubated in the dark at 25.0 +/- 1.0 degrees C for 30 days. Half-lives of 4.9 and 5.4 days were calculated for the chlorosalicylic acid- and chloronitroaniline-labeled test systems, respectively. From 0 to 21 days after treatment (DAT), the only metabolism product observed in either test system was aminoniclosamide. At the final sampling interval, five peaks were resolved from the chlorosalicylic acid label, and three peaks were resolved from the chloronitroaniline label test substance. By 30 DAT, sediment-bound residues represented approximately 70% of the observed radioactivity. For the anaerobic aquatic metabolism of [(14)C]niclosamide, test systems were incubated under anaerobic conditions for 365 days. Half-lives of 0.65 day for the chlorosalicylic acid label and 2.79 days for the chloronitroaniline label were calculated. From 0 to 3 DAT, niclosamide was first transformed into aminoniclosamide. Aminoniclosamide is readily formed, as it was observed in the chlorosalicylic acid label 0 DAT sampling. Several minor metabolites were observed in the water and sediment extracts. None of these metabolites were formed to a significant amount until the parent niclosamide dissipated below the detection limit. Two of the byproducts from these metabolism studies are polar unknowns eluting at 3 and 5 min by HPLC, similar to the unknowns observed in aqueous photolysis studies.

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Aqueous Photolysis of Niclosamide

Cited by 20 publications

References 21 publications

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Metabolism of 2-Chloro-4-Nitroaniline via Novel Aerobic Degradation Pathway by Rhodococcus sp. Strain MB-P1

Metabolism of Niclosamide in Sediment and Water Systems

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