Glutathione conjugates of ochratoxin A as biomarkers of exposure.

In the present study the photoreactivity of the fungal carcinogen ochratoxin A (OTA) has been utilised to generate authentic samples of reduced glutathione (GSH) and N-acetylcysteine (NAC) conjugates of the parent toxin. These conjugates, along with the nontoxic OTα, which is generated through hydrolysis of the amide bond of OTA by carboxypeptidase A, were utilised as biomarkers to study the metabolism of OTA in the liver and kidney of male and female Dark Agouti rats. Male rats are more susceptible than female rats to OTA carcinogenesis with the kidney being the target organ.

Structure-activity relationships imply different mechanisms of action for ochratoxin A-mediated cytotoxicity and genotoxicity.

Ochratoxin A (OTA) is a fungal toxin that is classified as a possible human carcinogen based on sufficient evidence for carcinogenicity in animal studies. The toxin is known to promote oxidative DNA damage through production of reactive oxygen species (ROS). The toxin also generates covalent DNA adducts, and it has been difficult to separate the biological effects caused by DNA adduction from that of ROS generation.

Binding of zearalenone, aflatoxin B1, and ochratoxin A by yeast-based products: a method for quantification of adsorption performance.

A methodology was developed to quantify the efficiency of yeast-based products for adsorption of three mycotoxins: zearalenone (ZEA), aflatoxin B(1) (AFB(1)), and ochratoxin A (OTA). Eight products were tested (yeast cell wall or inactivated yeast). The described experimental protocol based on in vitro tests provided reliable isotherms for each mycotoxin.

Ochratoxin A in roasted coffee from French supermarkets and transfer in coffee beverages: comparison of analysis methods.

The OTA content of 30 roasted coffees purchased in French supermarkets was evaluated by two validated different methods: one using immunoaffinity column (IAC) clean-up after alkaline extraction; the second using toluene extraction under acidic conditions. OTA recoveries (0.5 to 5 µg/kg) ranged from 16-49% with the alkaline extraction method and 55-60% with the acidic method.

Ochratoxin A: in utero exposure in mice induces adducts in testicular DNA.

Ochratoxin A (OTA) is a nephrotoxin and carcinogen that is associated with Balkan endemic nephropathy and urinary tract tumors. OTA crosses the placenta and causes adducts in the liver and kidney DNA of newborns. Because the testis and kidney develop from the same embryonic tissue, we reasoned that OTA also may cause adducts transplacentally in the testis.

Structure-activity relationships for the fluorescence of ochratoxin A: insight for detection of ochratoxin A metabolites.

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium that is widely found as a contaminant of food products. The toxin is a renal carcinogen in male rats, the cause of mycotoxicoses in pigs and has been associated with chronic human kidney diseases. Bioactivation has been implicated in OTA-mediated toxicity, although inconsistent results have been reported, due, in part, to the difficulty in detecting OTA metabolites in vivo.

New molecular and field evidences for the implication of mycotoxins but not aristolochic acid in human nephropathy and urinary tract tumor.

To find out whether ochratoxin A (OTA), citrinin (CIT), aristolochic acids (AA) are etiologic agents of Balkan endemic nephropathy (BEN) or Chinese herbal nephrotoxicity, and associated urinary tract tumor (UTT), we have compared (i) in human kidney cell culture, the DNA adduct formation and persistence of OTA/CIT and AA adducts (ii) analyzed DNA adduct in several tumors from human kidney suspected to be exposed to either OTA and CIT, or AAs (iii) analyzed OTA, CIT, and AA in food. In kidney cell cultures, formation of specific OTA-DNA adduct and AA-DNA adduct were detected in the same range (around 10 adducts/10(9) nucleotides) and were time- and dose-dependent. After 2 days all disappeared.

Genotoxicity of the hydroquinone metabolite of ochratoxin A: structure-activity relationships for covalent DNA adduction.

Ochratoxin A (OTA) is a mycotoxin that shows potent nephrotoxicity and renal carcinogenicity in rodents. One hypothesis for OTA-induced tumor formation is based on its genotoxic properties that are promoted by oxidative metabolism. Like other chlorinated phenols, OTA undergoes an oxidative dechlorination process to generate a quinone (OTQ)/hydroquinone (OTHQ) redox couple that may play a role in OTA-mediated genotoxicity.