<i>In vitro</i> Intestinal Microflora‐Mediated Metabolism of Biliary Metabolites from 1‐Nitropyrene‐Treated Rats

Kinouchi, Takemi; Nishifuji, Keiko; Ohnishi, Yoshinari

doi:10.1111/j.1348-0421.1987.tb01349.x

Cited by 8 publications

(9 citation statements)

References 40 publications

(49 reference statements)

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“…The ileal mucosae of rats were scraped off by glass slides on ice (16,17). A 10% homogenate of the ileal mucosa was prepared and the level of TBA-reactive substances was measured as described previously (15,28).…”

Section: Methodsmentioning

confidence: 99%

Protective Effects of a Culture Supernatant of Lactobacillus acidophilus and Antioxidants on Ileal Ulcer Formation in Rats Treated with a Nonsteroidal Antiinflammatory Drug

Bing

Kinouchi

Kataoka

et al. 1998

Microbiology and Immunology

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Ileal ulcers and thiobarbituric acid (TBA)‐reactive substances in the ileal mucosa were induced in rats treated with a nonsteroidal antiinflammatory drug, 5‐bromo‐2‐(4‐fluorophenyl)‐3‐(4‐methylsulfonylphenyl)thiophene (BFMeT), at a dose of 1,000 mg/kg administered with tap water as drinking water. However, the formation of ileal ulcers and TBA‐reactive substances in the ileal mucosa was repressed by giving the animals a culture supernatant of Lactobacillus acidophilus as drinking water. We measured the antioxidative activity of the culture supernatant and found that the supernatant inhibited the formation of t‐butyl hydroperoxide‐induced TBA‐reactive substances in erythrocyte membrane ghosts. Therefore, the effects of various known antioxidative compounds on the ileal ulcer formation induced by BFMeT were investigated. While α‐tocopherol, t‐butyl‐1,4‐hydroxyanisole and allopurinol did not repress ulcer formation after BFMeT treatment, ascorbic acid, dimethyl sulfoxide, glutathione and β‐carotene significantly inhibited formation. Among these compounds, ascorbic acid was the most effective. Accumulation of TBA‐reactive substances in the ileal mucosa after BFMeT treatment also decreased significantly in rats treated with ascorbic acid. In addition, the percentage of Gram‐negative rods in the ileal contents of rats treated with BFMeT and tap water was dramatically increased, but it was not increased in rats treated with BFMeT and these antioxidants. A positive correlation between the percentage of Gram‐negative rods and the number of ileal ulcers was also observed. These results suggest that lipid peroxidation mediated by oxygen radicals plays an important role in the induction of ileal ulcers by BFMeT in rats, and that lipopolysaccharide‐activated neutrophils probably produce highly reactive hypochlorous acid and hydrogen peroxide, which are inactivated by ascorbic acid and glutathione, respectively.

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Section: Methodsmentioning

confidence: 99%

Protective Effects of a Culture Supernatant of Lactobacillus acidophilus and Antioxidants on Ileal Ulcer Formation in Rats Treated with a Nonsteroidal Antiinflammatory Drug

Bing

Kinouchi

Kataoka

et al. 1998

Microbiology and Immunology

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“…Nitro-PAHs are metabolized by both reductive and oxidative pathways (nitroreduction, ring oxidation, or a combination of the two) (8,9,18,29,32,33,37). The reduction of nitro groups is catalyzed by several mammalian enzymes and also by intestinal bacteria (4,5,14,15,17,23,24,32).…”

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“…Intestinal microflora, which are dominated by obligate anaerobes, can modify a wide range of environmental chemicals either directly or through the enterohepatic circulation (17). Various anaerobic human, monkey, and rat intestinal microflora are capable of rapidly metabolizing 1-nitropyrene, dinitropyrenes, and 6-nitrochrysene to aromatic amines (4,5,14,17,23,24). In addition, anaerobic bacteria commonly associated with the gastrointestinal tract reduce nitro-PAHs to aromatic amines, indicating nitroreductase activity in these bacteria (4,15,17,18,24).…”

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“…Various anaerobic human, monkey, and rat intestinal microflora are capable of rapidly metabolizing 1-nitropyrene, dinitropyrenes, and 6-nitrochrysene to aromatic amines (4,5,14,17,23,24). In addition, anaerobic bacteria commonly associated with the gastrointestinal tract reduce nitro-PAHs to aromatic amines, indicating nitroreductase activity in these bacteria (4,15,17,18,24). Kinouchi and Ohnishi (19) have studied the enzymes that convert 1-nitropyrene to 1-aminopyrene in Bacteroidesfragilis and have purified one of these enzymes.…”

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Reduction of nitroaromatic compounds by anaerobic bacteria isolated from the human gastrointestinal tract

Rafil

Franklin

Heflich

et al. 1991

Appl Environ Microbiol

118

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Human intestinal microbial flora were screened for their abilities to reduce nitroaromatic compounds by growing them on brain heart infusion agar plates containing 1-nitropyrene. Bacteria metabolizing 1-nitropyrene, detected by the appearance of clear zones around the colonies, were identified as Clostridium leptum, Clostridium paraputrificum, Clostridium clostridiiforme, another Clostridium sp., and a Eubacterium sp. These bacteria produced aromatic amines from nitroaromatic compounds, as shown by thin-layer chromatography, high-pressure liquid chromatography, and biochemical tests. Incubation of three of these bacteria with 1nitropyrene, 1,3-dinitropyrene, and 1,6-dinitropyrene inactivated the direct-acting mutagenicity associated with these compounds. Menadione and o-iodosobenzoic acid inhibited nitroreductase activity in all of the isolates, indicating the involvement of sulfhydryl groups in the active site of the enzyme. The optimum pH for nitroreductase activity was 8.0. Only the Clostridium sp. required added flavin adenine dinucleotide for nitroreductase activity. The nitroreductases were constitutive and extracellular. An activity stain for the detection of nitroreductase on anaerobic native polyacrylamide gels was developed. This activity stain revealed only one isozyme in each bacterium but showed that the nitroreductases from different bacteria had distinct electrophoretic mobilities.

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Reductive Metabolism of Nitroaromatic and Nitropolycyclic Aromatic Hydrocarbons

Cerniglia

Somerville

1995

Biodegradation of Nitroaromatic Compounds

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In vitro Intestinal Microflora‐Mediated Metabolism of Biliary Metabolites from 1‐Nitropyrene‐Treated Rats

Abstract: To investigate the modifying

Cited by 8 publications

References 40 publications

Protective Effects of a Culture Supernatant of Lactobacillus acidophilus and Antioxidants on Ileal Ulcer Formation in Rats Treated with a Nonsteroidal Antiinflammatory Drug

Protective Effects of a Culture Supernatant of Lactobacillus acidophilus and Antioxidants on Ileal Ulcer Formation in Rats Treated with a Nonsteroidal Antiinflammatory Drug

Reduction of nitroaromatic compounds by anaerobic bacteria isolated from the human gastrointestinal tract

Reductive Metabolism of Nitroaromatic and Nitropolycyclic Aromatic Hydrocarbons

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