Protection of Selenium on Hepatic Mitochondrial Respiratory Control Ratio and Respiratory Chain Complex Activities in Ducklings Intoxicated with Aflatoxin B<Subscript>1</Subscript>

To investigate the protection of selenium on hepatic mitochondrial functions, 90 7-day-old ducklings were randomly divided into three groups (groups I–III). Group I was used as a blank control. Group II was administered with aflatoxin B₁ (0.1 mg/kg body weight). Group III was administered with aflatoxin B₁ (0.1 mg/kg body weight) plus selenium (sodium selenite, 1 mg/kg body weight). All treatments were given once daily for 21 days. The results showed that the activities of hepatic mitochondrial complexes I–IV in group II ducklings significantly decreased when compared with group I (P < 0.01). Furthermore, the activities of hepatic mitochondrial complexes I–IV in group III significantly increased when compared with group II (P < 0.05). The hepatic mitochondrial respiratory control ratio (RCR) in group II ducklings significantly decreased when compared with group I (P < 0.01). In addition, the hepatic mitochondrial RCR in group III significantly increased when compared with group II (P < 0.05). These results revealed that the aflatoxin B₁ significantly induced hepatic mitochondrial dysfunction in the activities of hepatic mitochondrial respiratory chain complexes I–IV and the RCR in ducklings. However, sodium selenite could significantly ameliorate the negative effect induced by aflatoxin B₁.     

Mycotoxins in South African foods: a case study on aflatoxin M<Subscript>1</Subscript> in milk

The contamination of cow’s milk at the farm level with aflatoxin M₁ was investigated in South Africa. Samples of feeds, forage, maize and milk were taken at nine dairy farms, and at the same time samples of the processed milk (retail milk) were collected from the respective dairies to which the farms delivered their milk. The feeds were analysed for aflatoxin B₁ and the milk samples for aflatoxin M₁ using high performance liquid chromatography (HPLC) and fluorescence detection. All milk samples from the dairy farms were positive for aflatoxin M₁, ranging from 0.02 μg/l to 1.5 μg/l. Retail milk was also frequently contaminated with AFM₁, at levels of 0.01-3.1 μg/l. High AFB₁ levels in feed materials on the farms supplying the raw milk indicate that various sources account for this contamination frequency in milk.     

A survey of aflatoxin B<Subscript>1</Subscript> and total aflatoxin contamination in baby food,peanut and corn products sold at retail in Indonesia analysed by ELISA and HPLC

Aflatoxin contamination has been well known as a world-wide health-threatening problem in tropical countries including Indonesia. This research was undertaken to determine the degree of aflatoxin contamination in different Indonesian foodstuffs. A preliminary survey was carried out to evaluate the level of total aflatoxin (AfT) and aflatoxin B₁ (AfB₁) contamination of baby foods, peanut products, and corn products, which were purchased from traditional markets and supermarkets in Indonesia during the year 2001-2002. Eighty two peanut products, 12 baby foods products, and 11 corn products from different brands were analysed for AfT and AfB₁ using the Enzyme-Linked Immunosorbent Assay (ELISA) method. The results indicate that, of the brands analysed, 35% of the peanut products were contaminated with aflatoxins at various levels (range 5 to 870 μg/kg). Peanut-chilli sauces had the highest percentage of AfT contamination 9/12 (75%), which was followed by traditional snacks 5/11 (45%), peanut butter 4/11 (40%), flour egg coated peanut 6/16 (37%), and peanut cake 3/10 (30%). Fried peanuts and roasted peanut were found to contain aflatoxin at relatively lower percentages of 9% and 8%, respectively. From the 12 analysed baby food samples, on the other hand, no sample was found to be contaminated with aflatoxins. Two of 11 samples (18%) of corn based products were contaminated with AfT, ranging between 5.8 and 12.4 μg/kg. Additionally, 30 selected samples in different concentration ranges were further analysed to verify the correlation between ELISA and HPLC techniques and results were compared.     

Mycotoxins and mycotoxigenic moulds in nuts and sunflower seeds for human consumption

A survey was carried out to obtain data on the occurrence of mycotoxins and the mycotoxin-producing potential of fungi isolated from nuts (almonds, peanuts, hazelnuts, pistachio nuts) and sunflower seeds in Spain. Thin-layer chromatography was used to separate the toxins. Aflatoxins were detected in one sample of almonds (95 ppb aflatoxin B₁ and 15 ppb aflaxtoxin B₂) and in one sample of peanuts at a level below 10 ppb of aflatoxin B1. 100% of samples showed variable incidence of fungal contamination. The predominant fungi present in samples were Penicillium spp, Aspergillus niger, A. flavus, A. glaucus and Rhizopus spp. The results showed that isolates of different species were able to produce aflatoxins B₁, B₂, G₁, and G₂, sterigmatocystin, ochratoxin A, patulin, citrinin, penicillic acid, zearalenone, and griseofulvin.     

Aflatoxin-producing Potential of Isolates of the Aspergillus flavus-oryzae Group from Peanuts (Arachis hypogaea)

Seventy-eight samples of farmer stock peanuts, representing peanuts grown in nine different geographical areas during 1964, were assayed for aflatoxin and examined for associated microflora. Only two samples contained more than 50 ppb of aflatoxin. Infestation by members of the Aspergillus flavus-oryzae group varied from 35 to 100% of the kernels per area and from 1 to 100% of the kernels per sample. Aflatoxin production by individual isolates ranged from 0 to 349,143 ppb under the test conditions employed. In general, the isolates produced 8 to 10 times more B₁ than B₂, and no isolate producing aflatoxins G₁ or G₂ was found. The importance of proper postharvest handling of peanuts is emphasized by the prevalence of isolates of A. flavus-oryzae capable of producing aflatoxins on farmers stock peanuts.     

Mycotoxins in several Polish food products in 2004–2005

In 2004–2005, samples of several selected Polish foods such as cereal products, nuts, dried fruits, coffee and culinary spices collected from Warsaw market and taken from food producers were analyzed on presence of aflatoxin B₁, B₂, G₁, G₂ (AF), ochratoxin A (OTA), zearalenone (ZEA) and deoxynivalenol (DON). After extraction and clean-up of extracts on immunoaffinity columns (IAC), mycotoxin analyses were carried out by HPLC using fluorescence and UV detectors. The concentrations of aflatoxins and ochratoxin A depending on the kind of sample ranged from 0.02 to 7.8 (one sample, of peanuts) and 0.02–11.9 μg/kg (one coffee sample), respectively. The levels of ZEA and DON were found to be below 50 °g/kg.     

Influence of Selenium on Body Weights and Immune Organ Indexes in Ducklings Intoxicated with Aflatoxin B<Subscript>1</Subscript>

To investigate the influence of selenium on body weights and the immune organ indexes in ducklings administrated with aflatoxin B₁ (AFB₁), 90 7-day-old ducklings were randomly divided into three groups (groups I–III). Group I was used as a blank control. Group II was administered with AFB₁ (0.1 mg/kg body weight). Group III was administered with AFB₁ (0.1 mg/kg body weight) plus sodium selenite (1 mg/kg body weight). All treatments were given once daily for 21 days. It showed that the ducklings’ bursa of fabricius, thymus indexes, and body weights in group II significantly decreased when compared with group I (P < 0.01). Furthermore, the spleen indexes significantly decreased (P < 0.01). However, the ducklings’ bursa of fabricius and thymus indexes, body weights in group III ducklings significantly increased when compared with group II (P < 0.01). In addition, the spleen indexes significantly decreased (P < 0.01). These results revealed that AFB₁ significantly affect ducklings’ growth and immune organs development. However, selenium significantly ameliorated the negative effects induced by AFB₁.     

Evaluation of the mycological status of luncheon meat with special reference to aflatoxigenic moulds and aflatoxin residues

The luncheon meat samples analyzed, which were produced locally by the two main luncheon meat producing companies in Egypt were relatively highly contaminated either by moulds and yeasts in general, aflatoxigenic species and aflatoxin residues in particular. The most frequently encountered fungi from the samples were yeasts, Aspergillus niger, A. flavus, Penicillium chrysogenum, Rhizopus stolonifer, Mucor circinelloides. Less common were Cladosporium sphaerospermum, Alternaria alternata, Mycosphaerella tassiana, P. aurantiogriseum and P. oxalicum. The most important aflatoxigenic species, A. flavus, was isolated frequently. It was 10% of the total fungal isolates from both samples of the two companies. Seven luncheon meat samples out of 50 analyzed were positive for aflatoxin B₁ or B₁ and G₁, while all samples were negative for aflatoxins B₂, G₂, M₁ and M₂. Aflatoxin B₁ was detected only in 4 and 3 samples out of 25 analyzed from each of company A and B, respectively. The highest detectable level, 11.1 ppb, was recorded in a sample from company B and the least, 0.5 ppb, in a sample from company A. Aflatoxin G₁, at concentration of 3.2 ppb, was detected in only one sample of the aflatoxin B₁ – contaminated 3 samples of company B: this sample also had the highest level of aflatoxin B₁. Some luncheon meat samples had higher numbers of aflatoxigenic A. flavus than others, however these samples were negative for aflatoxins. The hazardous potential of such contamination will be discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of Selenium on Hepatic Mitochondrial Antioxidant Capacity in Ducklings Intoxicated with Aflatoxin B<Subscript>1</Subscript>

The aim of the study was to investigate the effect of selenium on hepatic mitochondrial antioxidant capacity in ducklings administrated with aflatoxin B₁ (AFB₁). Ninety 7-day-old ducklings were randomly divided into three groups (groups I–III). Group I was used as a blank control. Group II was administered with AFB₁ (0.1 mg/kg body weight). Group III was administered with AFB₁ (0.1 mg/kg body weight) plus selenium (sodium selenite, 1 mg/kg body weight). All treatments were given once daily for 21 days. The results showed that the activities of mitochondrial superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione reductase (GR) in group II ducklings significantly decreased when compared with group I (P < 0.01). Furthermore, the content of hepatic mitochondrial malondialdehyde (MDA) significantly increased (P < 0.01). However, the activities of hepatic mitochondrial SOD, CAT, GSH-Px, and GR in group III ducklings significantly increased when compared with group II (P < 0.05). In addition, the content of hepatic mitochondrial MDA significantly decreased (P < 0.01). These results revealed that AFB₁ significantly induced hepatic mitochondrial antioxidant dysfunction. However, sodium selenite could significantly ameliorate the negative effect induced by AFB₁.     

Occurrence of aflatoxin M<Subscript>1</Subscript> in commercial pasteurized milk samples in Sari,Mazandaran province,Iran

The frequency and levels of aflatoxin M₁ (AFM₁) in pasteurized milk samples in Sari, located in Mazandaran province, Iran, were determined by enzyme immunoassay. Seventy-six samples of pasteurized milk from different retail stores were randomly collected over four seasons during the year 2015. AFM₁ contamination was detected in all milk samples. The mean concentration of aflatoxin M₁ was 65.8 ng/l, with a range of 11.7–106.6 ng/l. The highest AFM₁ level was detected in milk samples collected during spring. Forty-six (60.53 %) samples had AFM₁ levels that exceeded the maximum acceptable levels (50 ng/l) recommended by the European Union (EU). Comparison of these results with previously published data for AFM₁ in milk in Iran shows that the percentage of samples exceeding the EU maximum level is consistently high over the years, indicating a general problem related to AFB₁ contamination in dairy feedingstuff.     

Aflatoxins in peanut butter in Khartoum State,Sudan

Forty-three peanut butter samples from Khartoum State, Sudan, were analyzed for aflatoxins (AFs, AFB₁ + AFB₂ + AFG₁ + AFG₂) using high performance liquid chromatography (HPLC) with fluorescence detection after extraction with methanol:water (8:1, v/v) and clean-up using chloroform. All samples were contaminated with AFs, with total AF levels ranging between 26.7 and 853 μg/kg, and a mean total AF level of 287 ± 200.5 μg/kg. The highest concentrations were found for AFB₁, (28 positive samples, maximum 534 μg/kg), while AFG₁ was most frequently detected (43 positive samples, maximum 401 μg/kg). AFB₂ (42 positive samples, maximum 3.2 μg/kg) and AFG₂ (4 positive samples, maximum 30 μg/kg) were also present in these samples. The mean AF contamination levels found in this study exceeded by far all international regulations concerning maximum levels for this group of toxins. From the data, it is concluded that the levels of AF contamination in peanut butter from the Kartoum area are quite alarming, and may pose serious health hazards to consumers. Therefore, an intervention strategy to manage AF in peanut butter is urgently needed.     

Vitamin B<Subscript>12</Subscript> as a carrier for targeted platinum delivery: in vitro cytotoxicity and mechanistic studies

It is attractive to use vitamin B₁₂ as a carrier for targeted delivery of cytotoxic agents such as platinum complexes owing to the high demand for vitamin B₁₂ by fast proliferating cells. The basic {B₁₂–CN–Pt^II} conjugates are recognized by intracellular enzymes and converted to coenzyme B₁₂ in an enzymatic adenosylation assay. The reductive adenosylation of {B₁₂–CN–Pt^II} conjugates leads to the release of the Pt^II complexes; thus, {B₁₂–CN–Pt^II} conjugates can be considered as prodrugs. It is important not only to elucidate the activity of the cisplatin–B₁₂ conjugates, but also to understand the mode of action on a molecular level. Chemical reduction of {B₁₂–CN–Pt^II} conjugates with cobaltocene yielded cob(II)alamin and induced release of the corresponding Pt^II species. Kurnakov tests and coordination of 2′-deoxyguanosine or GMP to the released Pt^II complexes allowed isolation and characterization of Pt^II complexes as released during enzymatic adenosylation. The biological activity of these Pt^II complexes was evaluated. Since the cleaved Pt^II complexes show cytotoxicity, the {B₁₂–CN–Pt^II} conjugates can be used for specific targeting of cancer cells and therapeutic drug delivery. Preliminary in vitro cytotoxicity studies indicated lower activity (IC₅₀ between 8 and 88 μM) than found for pure cisplatin. Since active transport and receptor-mediated uptake limits the intracellular {B₁₂–CN–Pt^II} concentration, comparison with pure cisplatin is of limited use. We could show that the Pt^II complexes cleaved from B₁₂ exerted a cytotoxicity comparable to that of cisplatin itself. Cytotoxicity studies in vitamin B₁₂ free media showed a dependence on the addition of transcobalamin II for B₁₂–Pt(II) conjugates.     

Mechanism of action of aflatoxin B1

The inhibitory effects of aflatoxin B₁ were found to be related to the gram character in procaryotes, used in this study. Ethylene diamine tetra chloroacetic acid (0.05% w/v) or Tween-80 (0.05 % v/v) addition accentuated the aflatoxin B₁ growth inhibition inSalmonella typhi andEscherichia coli at different pH values. The inhibition of lipase production was only 5–20 % inPseudomonas fluorescence ca. 25–48% inStaphylococcus aureus andBacillus cereus at different aflatoxin B₁ concentrations (4–16μg/ml).However, inhibition of α-amylase induction was complete in1Bacillus megaterium whereas the inhibition was partial inPseudomonas fluorescence (27–40%) at 32μg aflatoxin B₁ concentration. An increase in leakage of cell contents and decreased inulin uptake were observed in toxin incubated sheep red blood cell suspension (1 %) with increased aflatoxin B₁ concentration     

Recent improvements in the development of A<Subscript>2B</Subscript> adenosine receptor agonists

Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named A₁, A_2A, A_2B and A₃ (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A_2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A_2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview of the recent advancements in identifying potent and selective A_2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N ⁶-, C²-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions. Compounds 1-deoxy-1-{6-[N′-(furan-2-carbonyl)-hydrazino]-9H-purin-9-yl}-N-ethyl-β-D-ribofuranuronamide (19, hA₁ K _i = 1050 nM, hA_2A K _i = 1550 nM, hA_2B EC₅₀ = 82 nM, hA₃ K _i > 5 μM) and its 2-chloro analogue 23 (hA₁ K _i = 3500 nM, hA_2A K _i = 4950 nM, hA_2B EC₅₀ = 210 nM, hA₃ K _i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay in Chinese hamster ovary (CHO) cells expressing hA_2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide (BAY-60–6583, hA₁, hA_2A, hA₃ EC₅₀ > 10 μM; hA_2B EC₅₀ = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis.     

Characterization of structure and activity of garlic peroxidase (POX<Subscript>1B</Subscript>)

Structural characterization and study of the activity of new POX_1B protein from garlic which has a high peroxidase activity and can be used as a biosensor for the detection of hydrogen peroxide and phenolic compounds were performed and compared with the findings for other heme peroxidases. The structure–function relationship was investigated by analysis of the spectroscopic properties and correlated to the structure determined by a new generation of high-performance hybrid mass spectrometers. The reactivity of the enzyme was analyzed by studies of the redox activity toward various ligands and the reactivity with various substrates. We demonstrated that, in the case of garlic peroxidase, the heme group is pentacoordinated, and has an histidine as a proximal ligand. POX_1B exhibited a high affinity for hydrogen peroxide as well as various reducing cosubstrates. In addition, high enzyme specificity was demonstrated. The k _cat and K _M values were 411 and 400 mM⁻¹ s⁻¹ for 3,3′,5,5′-tetramethylbenzidine and 2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), respectively. Furthermore, the reduction of nitro compounds in the presence of POX_1B was demonstrated by iron(II) nitrosoalkane complex assay. In addition, POX_1B showed a great potential for application for drug metabolism since its ability to react with 1-nitrohexane in the presence of sodium dithionite was demonstrated by the appearance of a characteristic Soret band at 411 nm. The high catalytic efficiency obtained in the case of the new garlic peroxidase (POX_1B) is suitable for the monitoring of different analytes and biocatalysis.     

Use of propolis and ultragriseofulvin to inhibit aflatoxigenic fungi

Propolis ethanolic extract (PEE) at 3 and 4 g/L and ultragriseofulvin (UG) at 0.75 and 1 g/L reduced the percentage of conidia germination in twoAspergillus flavus isolates. PEE at 1–4 g/L decreased the mycelial dry mass ofA. flavus isolates by 11–80%, and aflatoxin B₁ production by 34–100%. UG concentrations of 0.25–1 g/L reduced the growth and aflatoxin B₁ production of the isolates by 16–88 and 48–98%, respectively. Any increase in PEE and UG concentration was accompanied by a clear decrease in the per cent conidia germination, growth and aflatoxin B₁ production. At equal concentration, UG was about 4-times more effective than PEE.     

Comparative study on concentrations of deoxynivalenol and zearalenone in kernels of transgenic Bt maize hybrids and nontransgenic maize hybrids

A survey of aflatoxin contamination in selected Colombian foods was conducted over a 12-month period on a total of 248 samples. Samples were collected in supermarkets, retail stores and stock centres and were grouped into five categories: (1) corn and corn products, (2) cereal grains, (3) rice and rice products, (4) legume seeds; and (5) snacks and breakfast cereals. Aflatoxins were identified and quantitated using a liquid chromatographic technique with a limit of detection of 1 ng/g for each aflatoxin. Aflatoxins were detected in 14 of 109 samples of corn and corn products, 4 of 40 samples of rice and rice products, 2 of 30 samples of legume seeds, and 2 of 11 samples of snacks and breakfast cereals. None of the cereal grains samples analysed contained detectable levels of aflatoxins. Twelve of the total of 22 positive samples exceeded the maximum tolerable level of aflatoxin B₁ adopted in most countries (5 ng/g); 10 of these 12 samples corresponded to corn and corn products. The results of the present study indicate that aflatoxin B₁ contamination in certain foods in Colombia is a major public health concern. Continuous monitoring of aflatoxin B₁ levels in Colombian foods is advised.     

Natural occurrence of aflatoxins and ochratoxin a in corn and barley from mazandaran and golestan in north provinces of I. R. Iran

Fourteen barley and nine corn samples, destined for animal feed, collected from Golestan and Mazandaran provinces in the north of Islamic Republic of Iran (I. R. Iran) were analysed for aflatoxins (AF) and ochratoxin A (OA) by high performance liquid chromatography. In corn samples, aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) were detected in 8 (88.8%) and 6 (66.6%) samples at a mean level of 15.83 and 2.99 ppb (median 1.72 and 1 ppb), respectively. None of the corn samples contained detectable amounts of aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂). Only one of the AF-contaminated samples was co-contaminated with OA at a concentration of 0.35 ppb. This is the first report concerning natural occurrence of OA and co-occurrence with AF in corn samples of north of I. R. Iran.     

Biomolecule-functionalized magnetic nanoparticles for flow-through quartz crystal microbalance immunoassay of aflatoxin B<Subscript>1</Subscript>

A flow-through quartz crystal microbalance (QCM) immunoassay method has been developed based on aflatoxin B₁ antibody (anti-AFB₁)-functionalized magnetic core-shell Fe₃O₄/SiO₂ composite nanoparticles (bionanoparticles) in this study. To construct such an assay protocol, anti-AFB₁, as a model protein, was initially covalently immobilized onto the Fe₃O₄/SiO₂ surface, and then the functionalized nanoparticles were attached to the surface of the QCM probe with an external magnet. The binding of target molecules onto the immobilized antibodies decreased the sensor’s resonant frequency, and the frequency shift was proportional to the AFB₁ concentration in the range of 0.3–7.0 ng/ml. The regeneration of the developed immunosensor was carried out via attaching or detaching the external magnet from the detection cell. In addition, the selectivity, reproducibility, and stability of the proposed immunoassay system were acceptable. Compared with the conventional ELISAs, the proposed immunoassay system was simple and rapid without multiple labeling and separation steps. Importantly, the proposed immunoassay method could be further developed for the immobilization of other antigens or biocompounds.     

The effect of <Emphasis Type="Italic">Baccharis glutinosa</Emphasis> extract on the growth of mycotoxigenic fungi and fumonisin B<Subscript>1</Subscript> and aflatoxin B<Subscript>1</Subscript> production

The aim of this study was to evaluate the effect of Baccharis glutinosa isolated extract on the growth of Aspergillus flavus and Aspergillus parasiticus, and their aflatoxin B₁ production; and growth of Fusarium verticillioides, and their fumonisin B₁ production. The three fungi were exposed to an antifungal fraction, designated as fraction F6-1, isolated from B. glutinosa by methanolic extraction followed by silica gel chromatography. The growth of the fungi was evaluated in kinetics of radial extension growth, kinetics of spores germination, length and diameter of hyphae, spores diameter, as well as in aflatoxin B₁ and fumonisin B₁ production. Fraction F6-1 caused radial growth inhibition of the three fungi mainly F. verticillioides. Spores germination of A. flavus and A. parasiticus was delayed in the early stage of the incubation time, although they completely germinated at 27 h. In contrast, spore germination of F. verticillioides was inhibited 87.7% up to 96 h. The lengths and diameters of hyphae, and spore diameters of the three fungi, were significantly smaller in comparison with those of the controls, and several morphological alterations were observed. Concerning aflatoxin B₁ and fumonisin B₁, fraction F6-1 did not show any inhibition effect at the concentration used. Fraction F6-1 was able to significantly inhibit the development of the three fungi, mainly F. verticillioides. The strong inhibitory effect of F6-1 on hyphae and spores suggests that it interacted with the fungi cell walls, which caused severe deformities. Nevertheless, this fraction was unable in inhibiting mycotoxin production from the three fungi at the concentration tested.