Document Detail


Aflatoxin B1 epoxidation catalysed by partially purified human liver lipoxygenase.
MedLine Citation:
PMID:  9058535     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
(1) This study demonstrates for the first time the human liver lipoxygenase-mediated co-oxidation of aflatoxin B1 to the reactive metabolite, aflatoxin B1-8,9-epoxide, which rapidly hydrolyzes to dihydrodiol and preferentially binds to Tris. (2) The Tris-diol complex formed was quantitated fluorimetrically, based on its characteristic excitation at lambda ex = 395 nm and emission at lambda em = 435 nm. (3) The incubation of partially purified human liver lipoxygenase for 30 min under optimum assay conditions (3.5 mM linoleic acid and 50 microM aflatoxin B1 in Tris buffer at pH 7.2) resulted in the formation of 10.6 +/- 1.7 nmol Tris-diol/mg protein. (4) In addition to linoleic acid, other unsaturated fatty acids namely gamma-linolenic acid, cis-11, 14-eicosadienoic acid and arachidonic acid also supported the lipoxygenase mediated epoxidation of aflatoxin B1. (5) The enzymatic Tris-diol formation was significantly inhibited by all the lipoxygenase inhibitors tested in a concentration-dependent manner. (6) These results strongly suggest that lipoxygenase is capable of aflatoxin B1 metabolism and this may represent yet another pathway for the bioactivation of this hepatocarcinogen in the human liver.
Authors:
S K Roy; A P Kulkarni
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Xenobiotica; the fate of foreign compounds in biological systems     Volume:  27     ISSN:  0049-8254     ISO Abbreviation:  Xenobiotica     Publication Date:  1997 Feb 
Date Detail:
Created Date:  1997-07-08     Completed Date:  1997-07-08     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  1306665     Medline TA:  Xenobiotica     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  231-41     Citation Subset:  IM    
Affiliation:
Florida Toxicology Research Center, Department of Environmental and Occupational Health, College of Public Health, University of South Florida, Tampa 33612-3805, USA.
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MeSH Terms
Descriptor/Qualifier:
Aflatoxin B1 / metabolism*
Carcinogens / metabolism*
Catalysis
Humans
Lipoxygenase / metabolism*
Lipoxygenase Inhibitors / pharmacology
Liver / enzymology*
Nordihydroguaiaretic Acid / pharmacology
Chemical
Reg. No./Substance:
0/Carcinogens; 0/Lipoxygenase Inhibitors; 1162-65-8/Aflatoxin B1; 500-38-9/Nordihydroguaiaretic Acid; EC 1.13.11.12/Lipoxygenase

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