Aflatoxins compound

Liver cancer can also be a consequence of exposure to hepatotoxic chemicals. Natural hepatocarcinogens include fungal aflatoxins. Synthetic hepato-carcinogens include nitrosoamines, certain chlorinated hydrocarbons, polychlorinated biphenyls (PCBs), chloroform, carbon tetrachloride, dimethyl-benzanthracene, and vinyl chloride.Table 5.15 lists the chemical compounds that induce liver cancer or cirrhosis in experimental animals or... 

The number of clear human epidemiologic studies is small. A total of approximately 50 compounds (c.g., benzene, vinyl chloride) and complex e.xposures (e.g., aluminum production, tobacco smoke) have sufficient data available to permit their classification as human carcinogens. The most potent human carcinogens known, the aflatoxins. are of natural origin. Their presence in food products through infestation by toxin-producing fungi constitute a serious problem in several tropical and subtropical countries. 

This sample preparation involved, firstly, an extraction and the elimination of the solid matrix by filtration and, secondly, a concentration procedure employing a solid phase extraction cartridge. The compounds of interest were separated solely by dispersive interactions with the reversed phase. In the example given, the corn meal was spiked with the aflatoxins. 

Toxic compounds polychlorinated biphenyls, polycyclic aromatic hydrocarbons, organochlorine pesticides, chlorinated pesticides, dioxins, veterinary drug residues, hormone residues, aflatoxins, toxic compounds in shellfish. Compoimds of nutritional significance in foods vitamins, fat, lipids, carbohydrates, protein, energy-calorific value, proximates, dietary fibre, ash. Other compounds hormones in blood serum... 

Two of the most carcinogenic compounds known dibenzo[a,l]pyrene, a polycyclic aromatic hydrocarbon (PAH) and aflatoxin Bi, a fungal metabolite. 

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 potent carcinogen aflatoxin B1 is activated by generation of an epoxide on a dihydrofuran moiety [43]. The potent MBIs contained in grapefruit juice and in the herbal medication St J ohn s Wort are furanocoumarin compounds [44—46]. A similar moiety is also incorporated in the HIV protease inhibitor L-754,394, a potent CYP3A4 MBI [47]. 

Moving to toxic compounds, we encounter the infamous aflatoxin Bl, a mycotoxin considered to be a major cause of human liver cancer in some parts of the world. Thus, there are some estimates that, in China, as many as 1 in 10 adults die from liver cancer caused by aflatoxin [205]. Oxidation of... 

An example of the importance of sampling is in the determination of aflatoxins (a class of highly toxic compounds... 

Afiatoxin is one of the most mutagenic and carcinogenic natural compounds described to date. Traditional methods for the measurement of aflatoxins fall into two groups ... 

Charmley, L.L. and Prelusky, D.B., Decontamination of Fusarium mycotoxins, in Miller, J.D. and Tremholm, H.L., eds.. Grain - compounds Other Than Aflatoxin Mycotoxins, Eagan Press, St. Paul, 1994. 

It turned out that aflatoxin was actually a mixture of four different but closely related chemicals. All possessed the same molecular backbone of carbon, hydrogen, and oxygen atoms (which backbone was quite complex and not known to be present in any other natural or synthetic chemicals), but differed from one another in some minor details. Two of the aflatoxins emitted a blue fluorescence when they were irradiated with ultraviolet light, and so were named aflatoxin Bi and B2 the names aflatoxin Gi and G2 were assigned to the green-fluorescing compounds. The intense fluorescent properties of the aflatoxins would later prove an invaluable aid to chemists interested in measuring the amount of these substances present in various foods, because the intensity of the fluorescence was related to the amount of chemical present. 

Of course the chemists creating organic compounds are living (most of them anyway), but the compounds are created in laboratory flasks without the assistance of living organisms. Such synthesis is clearly different from, for example, the production of colors by flowers and aflatoxins by molds. 

A specific example involving aflatoxins is shown in Box 6.8. We shall see other examples of glutathione reacting as a nucleophile in detoxification reactions, where conjugation is not the result of nucleophilic substitution. For example, it might be nucleophilic addition to an electrophile such as an unsaturated carbonyl compound (see Box 10.20). 

Fortunately, nature provides an alternative nucleophile whose role is to mop up dangerous electrophiles such as aflatoxin Bi epoxide before they can do damage, and to remove them from the body. This compound is glutathione (see Box 6.6), a tripeptide composed of glutamic acid, cysteine, and glycine. 

A Large molecular weight compounds of diverse structures Erythromycin Gestodene Synthetic steroids Aflatoxin Bj, senecionine... 

Adye, J., and Mateles, R. I. (1964). Incorporation of labelled compounds in aflatoxins. Biochim. Biophys. Acta 86,418-420. 

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