Special Issue "Recent Advances in Ochratoxins Research"

Guest Editor
Prof. Dr. Annie Pfohl-Leszkowicz
National Agronomical High School of Toulouse (ENSAT), Unit of Toxicology & Food safety, 1 avenue de l’Agrobiopôle, BP 32607, 31326, Auzeville-Tolosane, France
E-Mail: leszkowicz@ensat.fr
Phone: +33 534 323 947
Fax: +33 534 323 947
Interests: mycotoxin; ochratoxin; fumonisin; zearalenone; biomarker; risk evaluation; environmental toxicology; polycyclic aromatic compounds; genotoxicity; DNA adduct; balkan endemic nephropathy; kidney cancer; biotransformation

Guest Editor
Prof. Dr. Richard A. Manderville
Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, N1G 2W1 Canada
Website: http://www.chembio.uoguelph.ca/manderville/
E-Mail: rmanderv@uoguelph.ca
Phone: +1 519 824 4120
Fax: +1 519 766 1499
Interests: DNA damage by phenolic toxins including ochratoxin A; Modified DNA bases as fluorescent probes

Dear Colleagues,

Ochratoxin A (OTA) is a naturally occurring chlorophenolic fungal toxin that contaminates a wide range of food products (cereals, coffee, cocoa, bean, peanut, spice, meat) and poses a serious risk for human and animal health, that includes: renal toxicity, reprotoxicity, neurotoxicity, immunotoxicity and mutagenicity. To date, it is one of the most potent renal carcinogens in rodents ever studied by the National Cancer Institute/National Toxicological Program. The available evidence suggests that OTA is a genotoxic carcinogen by induction of oxidative DNA lesions coupled with direct DNA adducts following bioactivation.

Harmful effects of OTA can be potentiated by possible synergistic action with other mycotoxins or contaminants. The existence of these synergies makes assessment of the exact role of OTA in human and animal pathologies far more complex, especially when it comes to long-term perspective. Continuous monitoring for the presence of OTA is imperative, as is the adequate response in term of legislative measures and good agricultural practices.

This special issue is devoted to recent advances in OTA research, through both research articles and comprehensive reviews focusing on animal and human toxicity, risk assessment, monitoring strategies (development of biomarkers), detoxification strategies for mitigation both animal and human health risk, and synergistic impact between OTA and other compounds.

Prof. Dr. Annie Pfohl-Leszkowicz
Prof. Dr. Richard A. Manderville
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed Open Access monthly journal published by MDPI.

• ochratoxins
• mycotoxins
• occurrence
• biosensor
• intake
• biomarkers
• mechanism of action
• synergy
• mitigation
• biotransformation
• risk assessment
• food/feed safety
• Penicillium
• Aspergillus

Type of Paper: Article
Title: Coexposure of Human Kidney Cells to Ochratoxin A and Fumonisin B₁ Stimulates Proliferation, Genotoxicity and a Synergistic Increase in ERK Signaling Pathway
Authors: Kheira Hadjeba-Medjdoub ¹, Chakib El Adlouni ², Virginie Faucet-Marquis ¹, Richard A. Manderville ^3,* and Annie Pfohl-Leszkowicz ^1,*
Affiliations:
¹ National Agronomical High School of Toulouse (ENSAT), Laboratory Chemical Engineering, Department Bioprocess & Microbial System, UMR CNRS/INPT/UPS 5503, 1 avenue de l’Agrobiopôle, BP 32607, 31326, Auzeville-Tolosane, France; E-Mail: annie.leszkowicz@free.fr (A.P.-L.);
² Faculty of Science, Department of Biology, Chouaib Doukkali University, El Jadida, Morocco;
³ Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, N1G 2W1 Canada; E-Mail: rmanderv@uoguelph.ca
Abstract: Fumonisin B₁ (FB₁) and ochratoxin A (OTA) are mycotoxins classified as possible human carcinogens. They co-exist in human food products and have been shown to act synergistically in stimulating nephrotoxicity in pigs. The goal of the present study was to determine the combined impact of the toxins in cultured human kidney cells (HK2). Parameters common to both FB₁ and OTA (cytotoxicity and activation of mitogen-activated protein kinase, MAPK), and features characteristic of the individual mycotoxins (DNA adduction by OTA and release of arachidonic acid (AA) by FB₁) were measured. Treatment of HK2 cells with the combined toxin mixture (FB₁ + OTA) was found to stimulate cell proliferation. Under analogous conditions FB₁ was weakly cytotoxic while OTA showed no impact on cell viability. The conditions for cell proliferation by (FB₁ + OTA) were then examined for DNA adduction, release of AA and activation of MAPK. OTA-mediated DNA adduction, as measured by ³²P-postlabeling, occurred at a quicker rate in the presence of FB₁, with maximum levels being detected following 2 h incubation; with OTA alone adducts were not observed until 7 h incubation. Release of AA by FB₁ was inhibited by OTA, although levels of AA, prostaglandins (PGs) and leukotriens (LTs) were higher for the combined toxin mixture than for OTA alone. Both mycotoxins individually increase ERK activation; together these mycotoxins synergistically enhance ERK activity. These findings correlate with studies carried out in pigs and suggest that stronger nephrotoxic damages to human kidney are likely from combined exposure of (FB₁ and OTA) versus the individual mycotoxins.

Type of Paper: Review
Title: Deleterious Effects of Mycotoxin Combinations Involving Ochratoxin A
Authors: Maja Šegvić Klarić ¹, Dubravka Rašić ² and Maja Peraica ²
Affiliations:
¹ Department of Microbiology, Faculty of Pharmacy and Biochemistry, University of Zagreb, Schrottova 39, HR-10000 Zagreb, Croatia; E-Mail: msegvic@pharma.hr
² Unit of Toxicology, Institute of Medical Research and Occupational Helath, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
Abstract: Ochratoxin A (OTA) is nephotoxic mycotoxin with carcinogenic properties. It was frequently detected in various foodstuffs all over the word but with significantly higer frequency and concentrations in endemic nephopathy (EN) areas. Even though food is often contaminated with more than one mycotoxin, most of the erlier studies were focused on occurrence and toxicology of single OTA. Only a limited number of surveys showed that OTA co-occurus in the food with mycotoxins (citrinin-CTN, Fusarium toxins, penicilic acid, aflatoxins) which exert nephrotoxic, carcinogenic or carcinogen-promoting activity. This review summarises the findings on OTA and its co-occurrence with mentioned mycotoxins in food in past decade as well as experimental data on their combined toxicity. So far, mycotoxin mixtures involving OTA applied in sub-toxic concentrations produced additive or synergistic effects in experimental models suggesting that these combinations represent significant health hazard. Special attention should be addressed to the mixtures, which include carcinogenic and cancer-promoting mycotoxins.

Type of Paper: Review
Title: Ochratoxin A: Occurrence, Risk and Remediation
Authors: Antonello Santini, Gian Carlo Tenore and Alberto Ritieni
Affiliation: Department of Pharmacy, Università di Napoli Federico II, via D. Montesano 49, 80131, Naples, Italy; E-Mail: alberto.ritieni@unina.it (A.R.)
Abstract: Several microfungi of Aspergillus and Penicillium species are mycotoxins producers. Among the secondary metabolites produced by these microfungi, ochratoxin A (OTA) is considered a treath for health and has been detected worldwide as contaminant in many different foodstuff and feed. The molecule, consisting of a p-chlorophenolic group containing a dihydroisocoumarin moiety amide-linked to a L-phenylalanine, can have several toxicological effects, e.g., nephrotoxic, hepatotoxic, neurotoxic, teratogenic, and immunotoxic. This review will focus on the general properties of OTA, including the possible toxigenic action on food and feed, the health risk connected to its presence, the analytical methods for its detection, occurrence and possible remediation.

Type of Paper: Review
Title: Ochratoxin A Toxicity and Protective Effects of Antioxidants
Authors: Valeria Sorrenti, C. Di Giacomo, R. Acquaviva, I. Barbagallo and F. Galvano
Affiliation: Department of Drug Science, Section of Biochemistry, University of Catania, Italy;E-Mail: sorrenti@unict.it (V.S.)
Abstract: It has been reported that Ochratoxin A (OTA) is toxic and is involved in the development of different type of cancers in rats, mice and humans. A growing number of in vitro and in vivo studies has been collected and described the evidence compatible with a role for oxidative stress in OTA toxicity and carcinogenity. Because the contribution of the oxidative stress response in the development of cancers is well established, a role in OTA carcinogenicity is plausible. Several studies have been performed to try to counteract the adverse effects of oxygen radicals generated under OTA-treatment. A number of molecules with various antioxidant properties were tested, using in vivo or in vitro models. Protection against OTA-induced DNA damage, lipid peroxidation as well as cytotoxicity was observed further confirming the link between OTA exposure and oxidative damage. These studies demonstrate that antioxidants are able to counteract the deleterious effects of chronic consumption of OTA and confirm the potential effectiveness of dietary strategies to counteract OTA toxicity.

Type of Paper: Article
Title: Natural Occurrence of Ochratoxin A and Penicillium Verrucosum in Winter Wheat in Ontario, Canada
Authors: Victor Limay-Rios, Pragyan Burlakoti and Art W. Schaafsma
Affiliation: University of Guelph, Ridgetown Campus, Ridgetown, Ontario, Canada; E-Mails: vlimayri@ridgetownc.uoguelph.ca (V.L.-R.); pburlako@ridgetownc.uoguelph.ca (P.B.); aschaafs@ridgetownc.uoguelph.ca (A.W.S.)
Abstract: The importance of Ochratoxin A (OTA) as a health risk to humans and domestic animals is clearly acknowledged. As a result of improved analytical methods with very low detection limits, worldwide OTA exposure by humans and animals has been revealed to be more widespread than originally thought. Managing the potential contamination of Ontario winter wheat with OTA requires an understanding of the occurrence of OTA-producing fungi as well as the agronomic conditions in the field, post-harvest and during storage that are conducive to toxin accumulation in grains. A total of 76 and 60 samples (10 kg) were collected in winter 2011 and 2012, respectively, from farms located in South Western, Ontario. About 63% of grain samples were taken from the centre top area of undisturbed on-farm bins about 0.3 m below the surface just before being loaded onto trucks. The remaining samples were collected from disturbed bins, at grain out-loading and from wagons. OTA, ochratoxin B (OTB) and citrinin (CTN) determination was carried out using a triple quadruple
ESI-LC-MS/MS system with a detection limit of 0.3, 0.5 and 0.5 μg/kg, respectively. OTA, OTB and CTN were found in only one sample from the centre top area from different farm each year. Fungal isolation was achieved by diluting the contaminated ground sample over a modified yeast extract sucrose media. Penicillium-like terracotta coloured colonies were isolated and their ability to produce OTA and CTN was quantitated by LC/MS-MS. The identification of P. verrucosum (PV) was confirmed by specific-primer-PCR method. The incidence of PV was evaluated in all the remaining samples. In 2011, PV colonies were found in 28% of grain samples from all Counties evaluated and all were able to produce OTA and CTN concomitantly. The colonies were found in the high moisture zone in untouched bins and their concentration varied greatly between locations. In the summer of 2011, the farm that tested positive for OTA was studied in detail. Soil, storage residue, filter dust and grain were screened for the presence of PV. The highest concentration of PV spores was found in the roof of the storage bin near the manhole opening where most moisture condensation takes place. No PV was isolated in hand harvested grains that were not in contact with the soil. The on-farm monitoring system was extended to 19 farms. In general, hand-harvested grain was less likely to be contaminated with PV spores than grain collected from tramp-lines in the field and where there had been plant lodging. Toxigenic PV colonies were found in the soil at all locations. In winter, water condensation above the high moisture area of the bin (top center) might trigger spore growth that could lead to OTA accumulation if PV spores are present.

Type of Paper: Article
Title: A DNA Sequence-Based Study on Polyketide Synthase Genes Involved in Ochratoxin A Biosynthesis in Aspergillus affinis (Section Circumdati)
Authors: Domenico Davolos * and Biancamaria Pietrangeli
Affiliation: INAIL–Research, Certification, Verification Area, Department of Productive Plants and Human Settlements (DIPIA), Via Urbana, 167, 00184 Rome, Italy; E-Mail: d.davolos@inail.it
Abstract: Aspergillus affinis (section Circumdati) is a novel ochratoxin A (OTA)–producing species we described by means of morphological and phylogenetic analysis. Recently we focused on genes codifying a–amylases, giving a new insight into its potential in biotechnological applications. The polyketide synthase genes (pks) involved in the OTA biosynthesis of A. affinis are, however, still unknown. In this study, we identified the pks putatively required for OTA biosynthesis of A. affinis. A comparative analysis was conducted for the novel pks in relation to homologous genes identified in the currently published genome sequences of aspergilli. A molecular phylogeny based on pks from OTA–producing Aspergillus species was also carried out to gain an insight into the evolutionary processes shaping these genes. Understanding the molecular level of OTA synthesis on a single mycotoxigenic Aspergillus species is an important knowledge base for developing advanced DNA sequence based–technology for the detection of OTA–producing aspergilli.