Masked mycotoxins: occurrence, metabolism and role in planta

Il seguente lavoro è stato incentrato sullo studio delle micotossine prodotte dal genere Fusarium, in particolare delle loro forme mascherate. Questi composti sono metaboliti secondari prodotti dalle piante attraverso meccanismi di coniugazione che coinvolgono leforme native delle suddette micotossine. Particolare attenzione è stata dedicata allo studio del DON-3-glucoside e dello ZEN-14-glucoside,in quanto rappresentano i principali derivati di DON e ZEN rispettivamente, che si ritrovano come contaminanti dei cereali. Il termine "micotossine mascherate" è nato circa dieci anni fa dall’osservazione che solitamente questi composti erano in grado di“sfuggire” alle analisi di routine a causa del diverso comportamento chimico rispetto ai loro rispettivi composti nativi. Questo studio è stato quindi suddiviso in tre parti. La prima rivolta allo sviluppo di un nuovo metodo analitico in grado di rivelare questi composti nei cereali e in particolare, alla valutazione della loro presenza in campioni di grano duro naturalmente contaminati. La seconda parte ha riguardato esperimenti in serra effettuati al fine di comprendere meglio il meccanismo di mascheramento del DON e la resistenza dei diversi genotipi di grano duro ad una delle malattie più gravi che colpiscono le piante di frumento. Nell'ultima parte di questo lavoro sono invece state effettuate indagini sugli effetti tossici delle micotossine mascherate e sul loro destino durante la digestione umana.This work is focused on the study of Fusarium masked mycotoxins, secondary metabolites produced by plants via conjugation mechanisms of the parent mycotoxins. A special focus was devoted to DON-3-glucoside and ZEN-14-glucoside, the main derivatives of DON and ZEN in grains. The term “masked mycotoxins” arose almost a decade ago from the observation that usually these conjugates escape routine analysis on account of their different chemical behavior in comparison to their parent compounds. This study has been divided into three parts. The first one is addressed to the development of a new analytical method able to reveal these compounds in cereals and, in particular, to study their occurrence in naturally contaminated durum wheat. The second part involved greenhouse experiments carried out in order to better understand the masking mechanism of DON and the resistance of different durum wheat genotypes to one of the most severe disease that affects wheat plants (Fusarium Head Blight). In the last part of the work investigations on the toxic effect of masked mycotoxins and their fate upon human digestion,were carried out

Тhe effect of Cr substitution for Fe on ferroelectric and magnetic properties of PbFe0.5Nb0.5O3, PbFe0.5Sb0.5O3 and BiFeO3 multiferroics

Проведены диэлектрические и мессбауэровские исследования сегнетоэлектрических и магнитных фазовых переходов в твердых растворах PbFe0.5-xCrxNb0.5O3, BiFe1-xCrxO3, PbFe0.5-xCrxSb0.5O3. Во всех этих системах замещение железа хромом разрушает как сегнетоэлектрический, так и магнитный дальний порядок.PbFe0.5-xCrxNb0.5O3, BiFe1-xCrxO3, PbFe0.5-xCrxSb0.5O3 solid solutions have been carried out. In all the systems studied Cr substitution for Fe destroys both ferroelectric and magnetic long-range order.Работа выполнена при поддержке Российского Фонда Фундаментальных Исследований (грант 16-52-0072 Бел_a) и Белорусского Республиканского Фонда Фундаментальных Исследований (грант T16R-079)

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink

Durum Wheat (Triticum Durum Desf.) Lines Show Different Abilities to Form Masked Mycotoxins under Greenhouse Conditions

Deoxynivalenol (DON) is the most prevalent trichothecene in Europe and its occurrence is associated with infections of Fusarium graminearum and F. culmorum, causal agents of Fusarium head blight (FHB) on wheat. Resistance to FHB is a complex character and high variability occurs in the relationship between DON content and FHB incidence. DON conjugation to glucose (DON-3-glucoside, D3G) is the primary plant mechanism for resistance towards DON accumulation. Although this mechanism has been already described in bread wheat and barley, no data are reported so far about durum wheat, a key cereal in the pasta production chain. To address this issue, the ability of durum wheat to detoxify and convert deoxynivalenol into D3G was studied under greenhouse controlled conditions. Four durum wheat varieties (Svevo, Claudio, Kofa and Neodur) were assessed for DON-D3G conversion; Sumai 3, a bread wheat variety carrying a major QTL for FHB resistance (QFhs.ndsu-3B), was used as a positive control. Data reported hereby clearly demonstrate the ability of durum wheat to convert deoxynivalenol into its conjugated form, D3G

Masked trichothecene and zearalenone mycotoxins withstand digestion and absorption in the upper GI tract but are efficiently hydrolyzed by human gut microbiota in vitro

Acknowledgements This study was funded by the Food Standards Agency UK (FS 102101). The contributions of GH and AJR were funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government.Peer reviewedPostprintPostprin