Simple high-performance liquid chromatography—fluorescence detection method for plasma, kidney and liver of rat as a tool for toxicology studies

High-Performance Liquid Chromatography-Fluorescence Detection Method for Ochratoxin A Quantification in Small Mice Sample Volumes: Versatile Application across Diverse Matrices Relevant for Neurodegeneration Research

Ochratoxin A (OTA) is a mycotoxin commonly found in various food products, which poses potential health risks to humans and animals. Recently, more attention has been directed towards its potential neurodegenerative effects. However, there are currently no fully validated HPLC analytical methods established for its quantification in mice, the primary animal model in this field, that include pivotal tissues in this area of research, such as the intestine and brain. To address this gap, we developed and validated a highly sensitive, rapid, and simple method using HPLC-FLD for OTA determination in mice tissues (kidney, liver, brain, and intestine) as well as plasma samples. The method was rigorously validated for selectivity, linearity, accuracy, precision, recovery, dilution integrity, carry-over effect, stability, and robustness, meeting the validation criteria outlined by FDA and EMA guidelines. Furthermore, the described method enables the quantification of OTA in each individual sample using minimal tissue mass while maintaining excellent recovery values. The applicability of the method was demonstrated in a repeated low-dose OTA study in Balb/c mice, which, together with the inclusion of relevant and less common tissues in the validation process, underscore its suitability for neurodegeneration-related research.

Oral subchronic exposure to the mycotoxin ochratoxin A induces key pathological features of Parkinson's disease in mice six months after the end of the treatment

Some epidemiological studies with different levels of evidence have pointed to a higher risk of Parkinson's disease (PD) after exposure to environmental toxicants. A practically unexplored potential etiological factor is a group of naturally-occurring fungal secondary metabolites called mycotoxins. The mycotoxin ochratoxin A (OTA) has been reported to be neurotoxic in mice. To further identify if OTA exposure could have a role in PD pathology, Balb/c mice were orally treated with OTA (0.21, 0.5 mg/kg bw) four weeks and left for six months under normal diet. Effects of OTA on the onset, progression of alpha-synuclein pathology and development of motor deficits were evaluated. Immunohistochemical and biochemical analyses showed that oral subchronic OTA treatment induced loss of striatal dopaminergic innervation and dopaminergic cell dysfunction responsible for motor impairments. Phosphorylated alpha-synuclein levels were increased in gut and brain. LAMP-2A protein was decreased in tissues showing alpha-synuclein pathology. Cell cultures exposed to OTA exhibited decreased LAMP-2A protein, impairment of chaperone-mediated autophagy and decreased alpha-synuclein turnover which was linked to miRNAs deregulation, all reminiscent of PD. These results support the hypothesis that oral exposure to low OTA doses in mice can lead to biochemical and pathological changes reported in PD.

Safety evaluation of Ochratoxin A and Citrinin after 28 days repeated dose oral exposure to Wistar rats

Mycotoxins, ochratoxin A (OTA), and citrinin (CTN) are toxic metabolites of filamentous fungi. The most common fungal species that produce OTA and CTN belong to genera Aspergillus, Penicillium, Fusarium, and Monascus, and these fungal species are found to be contaminant a wide range of grains, food, and food product. The aim of our study was to evaluate the sub-acute repeated dose oral toxicity of OTA and CTN in experimental rodents by following OECD test guidelines for testing chemicals no. 407 with minor modifications. Twenty-five rats of each sex were divided equally into five groups; vehicle control, OTA 25 μg/kg b. wt., OTA 100 μg/kg b. wt., CTN 25 μg/kg b.wt. and CTN 100 μg/kg b. wt. The results of this study showed no abnormal clinical signs during 28 days of the experimental period. We did not found any significant changes in body weight gain, food consumption pattern, organ weight, hematology except few parameters, and biochemical values in any of the treatment and control groups. However, histopathological observations revealed severe nephrotoxicity and mild follicular depletion in the spleen of 100 μg/kg b. wt. treated groups of both OTA and CTN mycotoxins. The findings of our study are of its first kind that reports the systemic toxicity of OTA and CTN oral exposure to laboratory rodents.

Studies on the Presence of Mycotoxins in Biological Samples: An Overview

Mycotoxins are fungal secondary metabolites with bioaccumulation levels leading to their carry-over into animal fluids, organs, and tissues. As a consequence, mycotoxin determination in biological samples from humans and animals has been reported worldwide. Since most mycotoxins show toxic effects at low concentrations and considering the extremely low levels present in biological samples, the application of reliable detection methods is required. This review summarizes the information regarding the studies involving mycotoxin determination in biological samples over the last 10 years. Relevant data on extraction methodology, detection techniques, sample size, limits of detection, and quantitation are presented herein. Briefly, liquid-liquid extraction followed by LC-MS/MS determination was the most common technique. The most analyzed mycotoxin was ochratoxin A, followed by zearalenone and deoxynivalenol—including their metabolites, enniatins, fumonisins, aflatoxins, T-2 and HT-2 toxins. Moreover, the studies were classified by their purpose, mainly focused on the development of analytical methodologies, mycotoxin biomonitoring, and exposure assessment. The study of tissue distribution, bioaccumulation, carry-over, persistence and transference of mycotoxins, as well as, toxicokinetics and ADME (absorption, distribution, metabolism and excretion) were other proposed goals for biological sample analysis. Finally, an overview of risk assessment was discussed.

Genotoxicity of Aflatoxin B1 and Ochratoxin A after simultaneous application of the in vivo micronucleus and comet assay

Aflatoxin B1 (AFB1) and Ochratoxin A (OTA) are genotoxic mycotoxins that can contaminate a variety of foodstuffs, the liver and the kidney being their target organs, respectively. The micronucleus (MN) assay (bone marrow) and the comet assay (liver and kidney) were performed simultaneously in F344 rats, treated with AFB1 (0.25 mg/kg b.w.), OTA (0.5 mg/kg b.w.) or both mycotoxins. After AFB1 treatment, histopathology and biochemistry analysis showed liver necrosis, focal inflammation and an increase in Alanine Aminotransferase and Aspartate Aminotransferase. OTA alone did not cause any alteration. The acute hepatotoxic effects caused by AFB1 were less pronounced in animals treated with both mycotoxins. With regard to the MN assay, after 24 h, positive results were obtained for AFB1 and negative results were obtained for OTA, although both toxins caused bone marrow toxicity. In the combined treatment, OTA reduced the toxicity and the number of MN produced by AFB1. In the comet assay, after 3 h, positive results were obtained for AFB1 in the liver and for OTA in the kidney. The combined treatment reduced DNA damage in the liver and had no influence in the kidney. Altogether, these results may be indicative of an antagonistic relationship regarding the genotoxicity of both mycotoxins.

The effects of orchidectomy on toxicological responses to dietary ochratoxin A in Wistar rats

Ochratoxin A (OTA) causes pathological lesions in the organs of animals. Males are more sensitive to OTA exposure than females but the reasons for this are unknown. The objective of this study was to explore the role of testosterone in male rats with OTA-related pathogenesis. To test the effect of testosterone on OTA toxicity, the testes of a group of rats were surgically removed. Male and female rats (approximately 300 and 200 g) were fed with OTA-contaminated feed (initially approximately 300 μg kg(-1) b.w. per day) for 24 weeks. The organs of all the animals were collected and their organ lesion pathology, caspase-3 expression, OTA plasma and organ concentrations and total plasma testosterone concentrations were evaluated. OTA treatment created serious lesions in the kidney, liver and testes of rats. The major histopathological changes in the kidney and liver were karyomegaly, hemorrhages and vacuolization. In the testes, there was a marked decrease in the amount of spermatozoon. The degrees of organ lesion were evaluated and the castrated males had the lowest kidney and liver lesion scores, indicating that testosterone reduction in males dramatically reduces OTA-related organ damage. The plasma OTA levels for the intact males, the castrated and the females were 6.34, 8.42 and 12.5 μg ml(-1), respectively. In conclusion, despite the similar plasma OTA levels of the intact and castrated males, OTA is less toxic in the castrated males. Therefore, the well-known gender specific toxicity of OTA seems to be related to the testosterone levels of rats.

Feeding a diet contaminated with ochratoxin A for broiler chickens at the maximum level recommended by the EU for poultry feeds (0.1 mg/kg). 2. Effects on meat quality, oxidative stress, residues and histological traits

The European Commission Recommendation 2006/576/EC indicates that the maximum tolerable level of ochratoxin A (OTA) in poultry feeds is 0.1 mg OTA/kg. Thirty-six 1-day-old male broiler chicks were divided into two groups, a control (basal diet) and an OTA (basal diet + 0.1 mg OTA/kg) group. The OTA concentration was quantified in serum, liver, kidney, breast and thigh samples. The thiobarbituric acid reactive substances (TBARS) content were evaluated in the liver, kidney, breast and thigh samples. The glutathione (GSH) content, and catalase (CAT) and superoxide dismutase (SOD) activity were measured in the liver and kidney samples. Histopathological traits were evaluated for the spleen, bursa of Fabricius and liver samples. Moreover, the chemical composition of the meat was analysed in breast and thigh samples. In the OTA diet-fed animals, a serum OTA concentration of 1.15 ± 0.35 ng/ml was found, and OTA was also detected in kidney and liver at 3.58 ± 0.85 ng OTA/g f.w. and 1.92 ± 0.21 ng OTA/g f.w., respectively. The TBARS content was higher in the kidney of the ochratoxin A group (1.53 ± 0.18 nmol/mg protein vs. 0.91 ± 0.25 nmol/mg protein). Feeding OTA at 0.1 mg OTA/kg also resulted in degenerative lesions in the spleen, bursa of Fabricius and liver. The maximum tolerable level of 0.1 mg OTA/kg, established for poultry feeds by the EU, represents a safe limit for the final consumer, because no OTA residues were found in breast and thigh meat. Even though no clinical signs were noticed in the birds fed the OTA-contaminated diet, moderate histological lesions were observed in the liver, spleen and bursa of Fabricius.

Effects of fasting and gender on ochratoxin A toxicokinetics in F344 rats

Ochratoxin A (OTA) is a mycotoxin that causes renal tumors in rats, particularly in males. In previous kinetic studies performed in fed conditions (Vettorazzi et al., 2008), mature F344 male rats presented a significantly lower OTA bioavailability than females and young animals. The objective of the present study was to evaluate two factors which could explain this different kinetic profile: the presence of food and the male-specific protein alpha-2u-globulin. Therefore, a 24h kinetic study has been performed in rats under fasting conditions. Food ingestion has been controlled in both sexes during two months. The presence of alpha-2u-globulin in the urine has been analyzed with SDS-gradient mini-gel electrophoresis. Fasting tends to increase the maximum OTA plasma concentrations and the rate of absorption. The relative bioavailability is significantly increased under fasting conditions only in males. Mature males consumed a higher amount of food but, as the OTA dose administered, it was proportional to body weight. The reason why the OTA bioavailability is more affected in presence of food only in males is unclear. Several possibilities, such as differences in gastric emptying, OTA-food interactions and the involvement of alpha-2u-globulin are discussed.

Review. Ochratoxin A: Presence in Human Plasma and Intake Estimation

Ochratoxin A (OTA) is a fungal toxic secondary metabolite that can be found in several foodstuffs and thereby ingested by humans. One way to assess exposure of humans to OTA is the determination of the levels of this mycotoxin in blood plasma from a certain population. Such studies have been done in many countries, both in healthy people and nephropathy patients. Relationships with individual characteristics were investigated in several cases. Thus, most studies found no correlation with age, either with gender. However, the few studies that found correlation between OTA plasma levels and gender showed that men presented the highest values. When sampling was done over more than one season, the highest OTA plasma levels were found mostly in summer. Differences within regions of a country were related to dietary habits of each area. OTA levels of group populations showed variations from year to year, whereas intraindividual repetitions showed no specific trend. Daily intake of the toxin can be estimated from OTA plasma concentrations by the Klaassen equation. OTA toxicokinetics are considered in this review. Calculated daily intake of OTA by different studies did not overpass the proposed tolerable daily intakes of OTA.

Developments in mycotoxin analysis: an update for 2008-2009

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2008 and mid-2009. It covers the major mycotoxins: aflatoxins, alternaria toxins, cyclopiazonic acid, fumonisins, ochratoxin, patulin, trichothecenes and zearalenone. Developments in mycotoxin analysis continue, with emphasis on novel immunological methods and further description of LC-MS and LC-MS/MS, particularly as multimycotoxin applications for different ranges of mycotoxins. Although falling outside the main emphasis of the review, some aspects of natural occurrence have been mentioned, especially if linked to novel method developments.