Of aflatoxin

Contamination of cottonseed by aflatoxins is a perennial concern. The FDA limits the amount of aflatoxin in cottonseed meal intended for beef catde, swine, and poultry to 300 ppb and for dairy catde the limit is 20 ppb. 

Test preparation for both methods is similar. It comprises an extraction by a water-acetone mixture with its further degreasing protein isolation and redistribution of aflatoxin B into chloroform, concentrating by means of evaporation of the dissolvent on the rotary evaporator (t = 40°C). 

Further interpretation of the CH COSY / CH COLOC plots allows additional assignments to be made for fragments B and C of aflatoxin B,. 

Triton X-100 ethoxyquin (antioxidant in spices) > 200-fold, stabilization > 15 h spray solution, 33% in benzene the fluorescence of aflatoxin Bi is reduced by 10 to 15% [292]. 

Enzymology and molecular biology of aflatoxin biosynthesis 97CRV2537. 

A. Farjam, R. de Vries, H. Lingeman and U. A. Th Brinkman, Immuno precolumns for selective on-line sample pretr eatment of aflatoxins in milk prior to column liquid cliro-matography , Int. J. Environ. Anal. Chem. 44 175-184 (1991). 

A. Farjam, N. C. van de Merbel, A. A. Nieman, H. Lingeman and U. A. Th Brinkman, Determination of aflatoxin Ml using a dialysis-based immunoaffinity sample pretreat-ment system coupled on-line to liquid cliromatography , ]. Chromatogr. 589 141-149(1992). 

The two examples of sample preparation of solids containing low concentrations of the substances of interest will be the analysis of aflatoxins in corn meal (7) and the determination of the fungicide thiabendazole in citrus fruits. It should be pointed out that the applications chosen in this section attempt to reflect a range of analyses that the analyst is likely to meet in both research and industrial laboratories. 

PRIMIANO T, EGNER P A, SUTTER T R, KELLOFF G J, ROEBUCK B D and KENSLER T W (1995) Intermittent dosing with oltipraz relationship between chemoprevention of aflatoxin-... 

In a clinical trial performed in China, the administration of 300 mg/day of copper chlorophyllin to humans who had detectable levels of serum aflatoxin due to unavoidable food contamination resnlted in a 50% reduction of median urinary levels of aflatoxin-DNA adducts. If health benefits from consuming natural chlorophylls were confirmed, it wonld be easy to add green leafy vegetables to a daily diet to obtain the benefit. Since leafy vegetables contain usually up to 200 mg chloro-phylls/100 g fresh weight, the intake of approximately 1 to 2 cups of raw spinach/day... 

Shier, W.T. et al.. Yellow pigments used in rapid identification of aflatoxin-producing Aspergillus strains are anthaquinones associated with the aflatoxin biosynthetic pathway, Bioorg Chem., 33, 426, 2005. 

De Palo, D., Gabucci, G., Valussi, S., Study on the possible presence of aflatoxin, sterigmatocystine and ochratoxin in green coffee, Colloq. Sci. Int. Cafe, 8, 539, 1977. (CA92 162258s)... 

Micco, C., Miraglia, M., Brera, C., Desiderio, C., Masci, V., The effect of roasting on the fate of aflatoxin B1 in artificially contaminated green coffee beans, Myc-otoxin Res., 8(2), 93, 1992. (CA118 146443y)... 

Gradelet, S., Le Bon, A.M., Berges, R., Suschetet, M., and Astorg, P. 1998. Dietary carotenoids inhibit aflatoxin Bl-induced liver preneoplastic foci and DNA damage in the rat Role of the modulation of aflatoxin B1 metabolism. Carcinogenesis 19 403—411. 

Beti J A, Phillips T W and Smalley E B (1995), Effects of maize weevils (Coleoptera Curculionidae) on production of aflatoxin B1 by Aspergillus flavus in stored corn , J. Economic Entomol., 88, 1776-1782. 

A Dotz benzannulation reaction was utilized in the synthesis of the furo[2,3- >]furan core of aflatoxin B2 as illustrated below <06TL2299>. Synthesis of polynuclear aromatic compounds was achieved by using [5+5] cycloaddition of 2-alkynylarylcarbene complexes and enyne-aldehyde derivatives <06TL5303>. 

The mode of action of this carcinogen is believed to involve epoxidation of a double bond (49), as indicated in Figure 3 in this Figure the similarities of the shapes, and particularly of the sites of activation of aflatoxin, BP and DMBA are demonstrated. Aflatoxin has functional groups at each end of the molecule, unlike an activated PAH which has functional groups only at one end of the molecule. 

Figure 3. (a) Similarities in the shapes of BP, DMBA, a base pair of guanine and cytosine, and the steroid, estradiol. In (b) the shapes of BD and DMBA (filled bonds) are compared with that of aflatoxin B] (open bonds) and the sites of activation of each to an epoxide is indicated by the arrows. 

Breinholt V, Hendricks J, Pereira C, Arbogast D and Bailey G. 1995. Dietary chlorophyllin is a potent inhibitor of aflatoxin Bi hepatocarcinogenesis in rainbow trout. Cancer Res 55(l) 57-62. 

Danley JM, Staggers S, Varner A, Llewellyn GC, Dashek WV. A combined biochemical and ultrastructural analysis of aflatoxin action on the endomembrane system of plant cells. Actual Bot 1982 129 5-13. 

Walker SJ, Llewellyn GC, Lillehoj EB, Dashek WV. Uptake and distribution of aflatoxin Bj in excised, soybean roots and toxin effects on root elongation. JEnviron ExperBot 1984 24 113-122. 

There is little doubt that the discovery of a class of chiral catalysts by Trost, represented by 102 in Scheme 15, constitutes one of the most important recent developments in asymmetric catalysis. The total synthesis of aflatoxin B, depicted in Scheme 15,... 

A protocol approved by the FDA to determine the safety of low gossypol cottonseed kernels for human consumption was the basis for the second study by Reber (7 ). To prepare raw cottonseed flour, raw kernels were ground to meet Ro-tap sieve specifications of lab chow. To prepare roasted cottonseed flour, raw kernels were dry roasted at not less than 121°C for not less than 5 min. To prepare cooked cottonseed flour, raw kernels were cooked in steam until batch temperature had been at or above 121°C for 5 min. All cottonseed kernels were ground in the manner described above. The kernels contained not more than 0.037% (370 ppm) of free gossypol. They were free of Salmonella and did not contain detectable amounts of aflatoxin. The proximate analyses of the cottonseed flours are shown in Table I. 

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