Aflatoxin chemical structure

Fig. 1. Chemical structure of aflatoxins. (a) The B-type aflatoxins are characterized hy a cyclopeutane E-ring. These compoimds have a hlue fluorescence under long-wavelength ultraviolet hght (h) The G-type aflatoxins have a xanthone ring in place of the cyclopentane, (c) Aflatoxins of the B2 and G2 type have a saturated bis-furanyl ring. Only the bis-firran is shown, (d) Aflatoxins of the Bi and Gi type have a hydrated his-furanyl structure.

Heathcote JG, Hibbert JR Biochemical effects, structure activity relationships in Goldblatt LA (ed) Aflatoxin Chemical and Biological Aspects. Amsterdam, Elsevier, 1978, pp 112-130. Dickens JW Aflatoxin control programme for peanuts. J Am Oil Chem Soc 1977 54 225A-228A. Goldblatt LA, Dollear FG Review of prevention, elimination and detoxification of aflatoxins. Pure Appl Chem 1977 49 1759-1764. 

Representative Compounds Aflatoxins Citrinin Ergot alkaloids Fumonisins Ochratoxin A Patulin Trichothecenes Zearalenone Stachybotrys toxin Chemical Formula C17H12O6 (Aflatoxin Bi) Chemical Structure Aflatoxin Bi... 

The aflatoxins B i), B2(S), Gj(P), and G2(10) occur as the major highly active constituents of the Aspergillus flavus species and have been isolated and separated by a number of workers2, 5> 19,32 51-53). The next problem to be assaulted was the determination of the chemical structures of these metabolites. Contributions to this effort were made by several groups19, 54-58 ... 

Purpose. DNA adducts are nucleotide bases (i.e., purines and pyrimidines) that have been covalently modified by reactive electrophilic chemical intermediates or free radicals. The chemical structures of DNA adducts are diverse and vary from simple alkyl adducts induced by alkylating agents to complex bulky adducts such as those resulting from metabolic activation of polycyclic aromatic hydrocarbons, aromatic amines, and aflatoxins (Dipple 1995 Chiarelli and Jackson 1992 Rundle 2006 Xue and Warshawsky 2005). The purpose of measuring DNA adducts is to determine whether a DNA-reactive compound or a metabolically activated... 

Thus, the aflatoxins form a family of highly oxygenated heterocychc compounds with closely similar chemical structures, that are formed naturally by certain species of moulds. 

The contradictory observations on the toxicity of coumarin stimulated our research into closely related coumarin derivatives in biochemical-pharmacological studies. Considering the limited information available in the various reviews on the biological properties of these compounds, the main emphasis in this paper will be placed on this aspect. It has been considered important to discuss the chemical structure-biological activity relationship of simple coumarins, coumarin anticoagulants, light sensitisers, aflatoxins, and related isocoumarin... 

FIGURE 6.3 Chemical structure of the different types of aflatoxins. Aflatoxins B and G occur in infested grains, whereas M aflatoxins are found in the milk of lactating animals fed contaminated feedstuffs. 

FIGURE 6.3 Chemical structure of the different types of aflatoxins.167... 

The structures of the products resulting from the chemical reduction of aflatoxins Bi(2) and B2(S), by a hydride source (sodium borohydride) are designated as afla-... 

In an effort to prepare sizable quantities of this liver metabolite for studies pertaining to structure vs biological activity relationships, Buchi and co-workers150 developed two methods of preparing aflatoxin Q1 (19), by the chemical transformation of natural aflatoxin Bt (1). 

Natural products represent a diversity of chemical compounds with varied biological activities. Natural products are an important source of novel pharmaceuticals as well as agricultural pesticides (1,2). Natural products are derived from a number of pathways that create basic scaffolds that are further modified by various tailoring enzymes to create the wide diversity of structures that exist in nature. Polyketide synthases are responsible for the synthesis of an array of natural products including antibiotics such as erythromycin in bacteria (3) and mycotoxins such as aflatoxin in fungi (4). Furthermore, in plants they are part of the biosynthetic machinery of flavonoids, phytoalexins, and phenolic lipi (5,6). 

The specificity of monoclonal antibodies make it possible to develop an analytical method for a single mycotoxin, such as aflatoxin Bi in maize and groundnut meal, or aflatoxin Mj in milk and milk products. Even within chemically closely related structures such as the Fusarium trichothecenes there is very little cross-reactivity between a monoclonal raised to a single toxin such as T-2 toxin and other members of the family. Thus, a monoclonal raised against 3-acetyl-deoxynivalenol showed negligible cross-reactivity with deoxynivalenol, nivalenol, or T-2 toxin. 

Most aflatoxins are chemically and structurally diverse. Since the majority of secondary metabolites are synthesized by simple biosynthetic reactions from small molecules (acetates, pyruvates, etc.), this is surprising, however, this leads to the compounds having such a diverse range of toxic effects, both acute and chronic [8]. 

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