Survey of fumonisins B1, B2 and B3 in conventional and organic retail corn products in Spain and Italy and estimated dietary exposure

A survey was conducted to determine the occurrence of fumonisin B₁, B₂ and B₃ during 2007 in 186 samples of organic and conventional locally available corn products. Samples included baby food (n = 62), corn flour (11), cornflakes (23), pasta (14), cookies (17) and other corn products (59) were obtained from popular markets of Valencia (Spain) and Perugia (Italy). The analytical method used pressurized liquid extraction and liquid chromatography/electrospray ionization tandem mass spectrometry with a triple quadrupole (QqQ) analyser. Of the 104 Spanish samples, 22% contained levels in the range of 2–449 µg kg^?1, 2–229 µg kg^?1 and 6–105 µg kg^?1 for FB₁, FB₂ and FB₃, respectively, while 19 (23%) of the 82 Italian samples were positive with quantifiable levels between 2–235 µg kg^?1, 3–187 µg kg^?1, and 4–40 µg kg^?1 for fumonisins B₁, B₂ and B₃, respectively. Overall, none of the Italian samples and only one organic baby food sample from a Spanish market was above the maximum permitted levels established by European legislation. Fumonisins were found mostly in corn flour followed by cookies and cornflakes. Eleven samples from Spain and nine samples from Italy were organic products, being contaminated the 72% and 77% of the samples, respectively. Analysis of the results showed that levels of fumonisins in corn products were similar in Italy and Spain. The safety of fumonisin intake through corn products was demonstrated by the calculation of the estimated daily intake of both populations considering organic and conventional products separately, which ranged from 1.7 × 10^?3 to 0.72 µg kg^?1 bw day^?1 and comparing them with the provisional maximum total daily intake (PMTDI) of 2 µg kg^?1 bw day^?1 established by the European Union.     

Alkaline cooking (nixtamalisation) and the reduction in the in vivo toxicity of fumonisin-contaminated corn in a rat feeding bioassay

Nixtamalisation is a widely used food processing method in which whole kernel corn is cooked and steeped in alkaline water. It reduces the amount of fumonisin B1 (FB₁) that can be detected after cooking. However, the fate of FB₁ during nixtamalisation is not fully understood and potentially toxic reaction products, including matrix-associated “masked” FB₁ forms that are not detected by routine analytical methods might remain in nixtamalised corn. To assess how nixtamalisation of whole kernel corn affects fumonisin toxicity, male rats were fed diets containing low, mid or high levels of uncooked (LU, MU, HU) or alkaline cooked (LC, MC, HC) FB₁-contaminated corn for 3 weeks. The control diet contained uncontaminated corn only. Apoptotic kidney lesions of the type caused by FB₁ were not found in the LC or MC groups. Lesions in the group fed HC were minimal and less severe than those found in the rats fed LU, MU or HU. Furthermore, significantly increased sphinganine and sphingosine concentrations indicative of FB₁ exposure were found in the kidneys of the rats given LU, MU or HU. Concentrations were also elevated, but to a lesser extent, in rats fed HC, whereas sphinganine and sphingosine concentrations in rats given LC or MC did not differ from the control group. FB₁ concentrations in the LC (0.08?mg?kg^?1), MC (0.13?mg?kg^?1) and HC (0.37?mg?kg^?1) diets were markedly reduced compared with their LU (1.8?mg?kg^?1), MU (3.5?mg?kg^?1) and HU (4.2?mg?kg^?1) counterparts as determined by HPLC (n?= 1 analysis/diet). Taken together, the findings show that nixtamalisation is an effective cooking method for reducing the potential toxicity of FB₁ contaminated corn.     

Co-contamination of aflatoxin B1 and fumonisin B1 in food and human dietary exposure in three areas of China

Aflatoxins and fumonisins are ubiquitous foodborne toxicants and the co-occurrence of these mycotoxins in human foods represents a significant public health concern, which has been strongly associated with human aflatoxicosis, neural tube defects, as well as many types of primary cancers. In this study the co-contamination of aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁) in food and human dietary exposure was investigated in residents of three different areas of China. A total of 209 food samples were measured for AFB₁ and FB₁. The median AFB₁ levels were 13.5, 2.3 and 1.3?µg?kg^?1 and the median FB₁ levels were 2.6, 0.4 and 0.3?mg?kg^?1 in corn samples collected from Huaian (a high-risk area for oesophageal cancer), Fusui (a high-risk area for liver cancer) and Huantai (a low-risk area for both oesophageal and liver cancers), respectively. The median level of AFB₁ in plant oil of Fusui was the highest (52.3?µg?kg^?1) among all food samples analysed. Co-contamination of these two mycotoxins was found in corn, rice and wheat flour. Based on measured food consumption data, the averaged daily dietary intake of AFB₁ was 0.397?µg (range?=?0.269–1.218?µg) in residents of Huantai, 1.723?µg (0.224–49.772?µg) in Huaian, and 2.685?µg (1.006–14.534?µg) in Fusui. The averaged FB₁ daily dietary intake was 92.4?µg (range?=?55.0–362.1?µg) for residents of Huantai, 460.0?µg (83.2–2894.5?µg) in Huaian, and 138.6?µg (30.0–10,541.6?µg) in Fusui. These data suggest that the co-exposure to AFB₁ and FB₁ in residents of rural China may contribute to the aetiology of human chronic diseases in high-risk areas.     

同位素稀释-超高效液相色谱-串联质谱法测定谷物中隐蔽型伏马菌素

目的 建立谷物中隐蔽型伏马菌素的同位素稀释.超高效液相色谱.串联质谱测定方法.方法 谷物样品溶剂提取后,一部分稀释后用于原型伏马菌素(FBs)检测,另一部分经碱水解后经强阴离子交换(MAX)柱净化用于水解型伏马菌素(HFBs)检测.0.2％甲酸甲醇-0.2％甲酸水作为流动相梯度洗脱,CORTECS C18色谱柱(2.1...     

Kinetics of fumonisin B1 formation in maize ears inoculated with Fusarium verticillioides

The kinetics of fumonisin B₁ (FB₁) biosynthesis have been examined in ears of four botanical varieties Zea mays var. indentata, Zea mays var. indurata, Zea mays var. saccharata and Zea mays var. everta inoculated with F. verticillioides isolates at silking stage. The level of mycotoxin accumulated in kernels was correlated with sample harvest time (r?=?0.73) and ergosterol content (r?=?0.70). FB₁ biosynthesis was influenced by amylose, starch and moisture contents, which undergo dynamic changes during grain formation. A comparative analysis of ear infection rates and efficiency of FB₁ biosynthesis showed that these are separate characters and their expression could be independent.     

Calcium montmorillonite clay reduces urinary biomarkers of fumonisin B1 exposure in rats and humans

Fumonisin B₁ (FB₁) is often a co-contaminant with aflatoxin (AF) in grains and may enhance AF's carcinogenicity by acting as a cancer promoter. Calcium montmorillonite (i.e. NovaSil, NS) is a possible dietary intervention to help decrease chronic aflatoxin exposure where populations are at risk. Previous studies show that an oral dose of NS clay was able to reduce AF exposure in a Ghanaian population. In vitro analyses from our laboratory indicated that FB₁ (like aflatoxin) could also be sorbed onto the surfaces of NS. Hence, our objectives were to evaluate the efficacy of NS clay to reduce urinary FB₁ in a rodent model and then in a human population highly exposed to AF. In the rodent model, male Fisher rats were randomly assigned to either FB₁ control, FB₁?+?2% NS or absolute control group. FB₁ alone or with clay was given as a single dose by gavage. For the human trial, participants received NS (1.5 or 3?g?day^?1) or placebo (1.5?g?day^?1) for 3 months. Urines from weeks 8 and 10 were collected from the study participants for analysis. In rats, NS significantly reduced urinary FB₁ biomarker by 20% in 24?h and 50% after 48?h compared to controls. In the humans, 56% of the urine samples analysed (n?=?186) had detectable levels of FB₁. Median urinary FB₁ levels were significantly (p?<?0.05) decreased by >90% in the high dose NS group (3?g?day^?1) compared to the placebo. This work indicates that our study participants in Ghana were exposed to FB₁ (in addition to AFs) from the diet. Moreover, earlier studies have shown conclusively that NS reduces the bioavailability of AF and the findings from this study suggest that NS clay also reduces the bioavailability FB₁. This is important since AF is a proven dietary risk factor for hepatocellular carcinoma (HCC) in humans and FB₁ is suspected to be a dietary risk factor for HCC and oesophageal cancer in humans.     

Sphinganine and sphingosine levels and ratio in urine and blood samples from a Catalonian population,Spain

Fumonisins occur mainly in maize and they produce alterations on sphingolipid metabolism, unbalancing the sphinganine (Sa)/sphingosine (So) ratio. This alteration has been proposed as a biomarker of fumonisin exposure. The objective of this study was to establish the urinary and plasmatic levels of Sa, So as well as the ratio Sa/So from a sample of the Catalonian (Spain) population exposed to fumonisins at low levels. Firstly, plasma and urinary Sa and So levels and the ratio Sa/So were compared between two population groups, and later urinary Sa and So levels from corn food consumers and a control group were monitored for 2 weeks under controlled intake of corn foods. Sa and So levels were determined in urine and blood samples using validated methods using HPLC with fluorescence detection. Significant differences were not found in urine samples when Sa/So ratios were compared from corn food consumers and non-consumers, while significant differences were found in urine and plasma samples, but evidence of the mechanism of action of fumonisins was not apparent. Through a time-course study we have narrowed down the day in which the maximum alteration of Sa/So ratio should be expected in humans. This paper reports some useful information to improve the design of studies to validate the ratio Sa/So as a possible biomarker of fumonisin exposure.     

Associations of planting date,drought stress,and insects with Fusarium ear rot and fumonisin B1 contamination in California maize

Fusarium ear rot, caused by Fusarium verticillioides, is one of the most common diseases of maize, causing yield and quality reductions and contamination of grain by fumonisins and other mycotoxins. Drought stress and various insects have been implicated as factors affecting disease severity. Field studies were conducted to evaluate the interactions and relative influences of drought stress, insect infestation, and planting date upon Fusarium ear rot severity and fumonisin B₁ contamination. Three hybrids varying in partial resistance to Fusarium ear rot were sown on three planting dates and subjected to four irrigation regimes to induce differing levels of drought stress. A foliar-spray insecticide treatment was imposed to induce differing levels of insect injury. Populations of thrips (Frankliniella spp.), damage by corn earworm (Helicoverpa zeae), Fusarium ear rot symptoms, and fumonisin B₁ levels were assessed. There were significant effects of hybrid, planting date, insecticide treatment, and drought stress on Fusarium ear rot symptoms and fumonisin B₁ contamination, and these factors also had significant interacting effects. The most influential factors were hybrid and insecticide treatment, but their effects were influenced by planting date and drought stress. The more resistant hybrids and the insecticide-treated plots consistently had lower Fusarium ear rot severity and fumonisin B₁ contamination. Later planting dates typically had higher thrips populations, more Fusarium ear rot, and higher levels of fumonisin B₁. Insect activity was significantly correlated with disease severity and fumonisin contamination, and the correlations were strongest for thrips. The results of this study confirm the influence of thrips on Fusarium ear rot severity in California, USA, and also establish a strong association between thrips and fumonisin B₁ levels.     

In vitro inhibitory effect of tetrahydrocurcuminoids on Fusarium proliferatum growth and fumonisin B1 biosynthesis

Many plant pathogens produce toxic metabolites when growing on food and feed. Some antioxidative components seem to prevent fungal growth and mycotoxin formation. Recently, we synthesized a new class of powerful antioxidative compounds, i.e. tetrahydrocurcuminoids, and its structure/antioxidant activity relationships have been established. The South West of France produces large amounts of corn, which can be infected by Fusarium species, particularly F. proliferatum. In this context, the efficiency of tetrahydrocurcuminoids, which can be obtained from natural curcuminoids, was investigated to control in vitro the growth of F. proliferatum and the production of its associated mycotoxin, fumonisin B₁. The relation between structure and antifungal activity was studied. Tetrahydrocurcumin (THC1), with two guaiacyl phenolic subunits, showed the highest inhibitory activity (measured as radial growth on agar medium) against the F. proliferatum development (67% inhibition at a concentration of 13.6?µmol?ml^?1). The efficiencies of THC2 (36% at a concentration of 11.5?µmol?ml^?1), which contains syringyl phenolic units, and THC3 (30% at a concentration of 13.6?µmol?ml^?1), which does not have any substituent on the aromatic rings, were relatively close. These results indicate that the simultaneous presence of guaiacyl phenols and the enolic function of the β-diketone moiety play an important role in the inhibition mechanisms. The importance of this combination was confirmed using n-propylguaiacol and acetylacetone as molecular models. Under the same conditions, ferulic acid and eugenol, other natural phenolic antioxidants, were less efficient in inhibiting fungal growth. THC1 also reduced fumonisin B₁ production in liquid medium by approximately 35, 50 and 75% at concentrations of 0.8, 1.3, and 1.9?µmol?ml^?1, respectively. These very low inhibitory concentrations show that tetrahydrocurcuminoids could be one of the most promising biobased molecules for the control of mycotoxinogen fungal strains.     

Fumonisins and their masked forms in maize products

In recent years many papers on masked mycotoxins in maize-based products appeared, including reports on fumonisins capable to form non-covalent bonds with food macro constituents. Such so-called “hidden fumonisins” are frequently present in food at quantities higher than the free forms. The aim of this work was to assess levels of free and total (free + hidden) fumonisins (B₁, B₂ and B₃) in 88 maize products available on the Polish retail market. Isotope dilution ion trap mass spectrometery coupled to a high performance liquid chromatography was used. 57% of all tested samples contained free fumonisins at concentrations above our limit of quantification LOQ (mean 390 ± 676 μg/kg). More than 77% of the samples contained free + hidden fumonisins at concentrations above LOQ (mean 574 ± 1177 μg/kg). The highest mean fumonisins concentrations 1006 ± 1131 μg/kg, 1651 ± 2317 μg/kg, respectively for free and free + hidden forms were observed in the group of maize snacks. The lowest fumonisin concentrations were found in maize-based starch concentrate products. None of the tested products within that group had free fumonisins concentrations above LOQ, while mean concentration of free + hidden fumonisins was as low as 82 ± 42 μg/kg. In thermally processed products like corn flakes and various snacks the hidden-to-free fumonisin concentration ratio was higher than in unprocessed products like flour, groats or raw popcorn grains.