Biotransformation aflatoxin

See also Acetaminophen Acetylaminofluorene Acetyl-salicylic Acid Aflatoxin Biotransformation Blood Bromo-benzene Carbon Tetrachloride Chloroform Dioxins Distribution Ethanol Excretion Immune System Is-oniazid Lipid Peroxidation Metallothionein Peroxisome Proliferators Tissue Repair. 

Finally, biological detoxification or biotransformation, or degradation of mycotoxins, especially aflatoxin by microbial systems to a metabolite(s) that is... 

Heinonen JT, Fisher R, Brendel K, Eaton DL Determination of aflatoxin Bj biotransformation and binding to hepatic macromolecules in human precision liver slices. Toxicol Appl Pharmacol 1996 136 1-7. 

Buetler TM, Bammler TK, Hayes JD, Eaton DL Oltipraz-mediated changes in aflatoxin B, biotransformation in rat liver implication for human chemointervention. Cancer Res 1996 56 2306-2313. 

The principal biotransformation of toxicants is catalyzed by the microsomal mixed function oxidase system (MFO). A deficiency of essential fatty acids generally depresses MFO activities. This is also true with protein deficiency. The decreased MFO has different effects on the toxicity of chemicals. For example, hexobarbital and aminopyrine are detoxified by these enzymes and are thus more toxic to rats and mice with these nutrient deficiencies. On the other hand, the toxicity of aflatoxin is lower in such animals because of their depressed bioactivation of this toxicant. MFO activities are decreased in animals fed high levels of sugar. 

Both quantitative and qualitative differences have been reported in the biotransformation of xenobiotics by different animal species (25, 26). Initially, indications for this phenomenon came primarily from toxicity studies with smil laboratory animals, showing species-differences in the sensitivity towards the toxic effects of a compound. In vivo studies have for example revealed a large difference between rats and mice in their sensitivity to the hepatotoxic and carcinogenic properties of aflatoxin (27). More recently, species-related differences in the biotransformation of compounds were shown in studies with isolated cellular fractions from livers of different animal species, including farm animals (28, 29, 30, 31, 32). 

The development of procedures for the isolation of hepatocytes from livers of different species, including man, have allowed the use of this model for comparative studies on the species-related biotransformation and toxicity of xenobiotics. In vitro studies with aflatoxin Bj showed that rat hepatocytes were more sensitive than those from mice, as became apparent by the death of the cells at much lower concentrations, the much higher levels of binding of metabolites of aflatoxin B1 to TCA-precipitable cell-material 33, 34), and the much higher levels of unscheduled DNA-synthesis (55). In addition, the mycotoxin caused segregation of nucleolar components in rat hepatocytes, but not in cells from mice 36). 

Plants can carry out biotransformations of aflatoxins, as made clear by Howes et al. [26], who studied the metabolism of aflatoxin B, in Petroaelinum crispum (Parsley). On administration of AFBj to whole plants, aflatoxicol was formed. The cell-free preparations, on the other hand, formed two new aflatoxin Bj or aflatoxicol A. Even plant products, such as neem-leaf extracts, have been shown to control aflatoxin production in Aspergillus avus-infected cotton bolls [27]. Sometimes, the genetic constitution of the aflatoxin contaminated plant commodity can take... 

In our laboratory, the effect of chronic ethanol consumption on the hepatic formation of macromolecular adducts was examined (Misslbeck, 1983). Rats consumed ethanol at 35% of calories in a liquid diet for 5 wk prior to injection with 1 mg H-aflatoxin 6,/kg body weight. No effect of ethanol on the in vivo formation of macromolecular adducts of H-aflatoxin Bj and DNA, RNA, or protein at 2, 24, or 48 hr after injection was observed (Misslbeck, 1983). In another study on macromolecular adduct formation, Obidoa and Okola (1979) found that binding of afiatoxin Bj to DNA was actually reduced in rats consuming ethanol (10% v/v in the drinking water). However, ethanol consumption did not enhance the biotransformation of afiatoxin Bj by liver slices in that study. 

Piperine is known to modify the biotransformation of drugs. Piperine-treated rat liver microsomes demonstrated a tendency to enhance [3H]-aflatoxin B1 binding to calf thymus DNA in vivo. The effect of piperine on aflatoxin B1 metabolism thus closely resembles the mode of action of SKF 525-A oti biotransformation of foreign... 

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