Mycotoxins discussion

In order to identify chemically the so-caUed monascidin A discussed by some Chinese scientists in their papers as a component suitable for the preservation of food, it was isolated and chemical investigations using mass spectrometry and NMR were undertaken. Monascidin A was characterized as citrinin which is known to be a mycotoxin responsible for nephropathies. Thus, in order to avoid the production of this toxin, various strains were screened in order to see whether all were toxino-genic and it was shown that among the species of Monascus available in pubhc collections, non-toxinogenic strains were obtainable. 

This document deals only with estimating exposure to direct additives and chemical contaminants. The procedures used to estimate exposure to chemical contaminants in food (including naturally occurring toxicants, such as mycotoxins) are essentially the same as those used for direct additives. Thus, contaminants will be considered in the discussion of direct additive exposure estimation. The procedures discussed herein are equally applicable to color additives, GRAS substances, prior-sanctioned ingredients, and pesticide residues. 

In this section, tetramic acids with an acyl group substituent at C-3 are discussed. The simplest of the naturally occurring 3-acyl tetramic acids, tenuazonic acid (6), was first isolated from the culture filtrate of Alter-naria tenuis [18] and, subsequently, from other fungal species (A. alternate, A. longipes, Pyricularia oryzae) [19,20]. Species of Altemaria are known to produce more than 70 secondary metabolites, many of which, particularly those from the Altemaria altemata complex, are mycotoxins [19]. The absolute stereochemistry of 6 (55,65) was deduced from the formation of L-isoleucine on ozonolysis followed by acid hydrolysis [21]. 

The different biosynthetic pathways through which mycotoxins are produced result in a broad diversity of chemical structures and, consequently, in a variety of toxic effects in humans and animals. An excellent review of the toxic effect of mycotoxins (3) is based on a system approach, where the toxic effects are discussed on the basis of the body systems affected by the mycotoxins. Hepatotoxic, gastrointestinal, hematopoietic, and nephrotoxic effects are treated, as well as... 

Aflatoxins, ochratoxin A, patulin, nivalenol, deoxynivalenol, fumonisins and zearalenone have been evaluated by the Scientific Committee for Food. The question of maximum levels for some of these mycotoxins in foodstuffs has been discussed for several years in the Committee of Experts - Working Party on Agricultural Contaminants under DG VI (now under DG SANCO). Proposals from this committee are then considered by the Standing Committee on Foodstuffs, prior to adoption by the Commission as Commission Regulations. 

From the preceding discussion, it becomes obvious that a considerable amount of economic importance is attached to the determination of the physiological effects of these mycotoxins. Additionally, safe limits for human ingestion would have to be set and enforced. 

The aim of this chapter is to summarize and critically discuss scientific data on mycotoxins in fruits. After giving an introduction on mold spoilage of fruits in general and factors affecting growth and mycotoxin formation by... 

The assoeiation of fungi with mammalian diseases came to the fore in 1960 with the diseovery of the aflatoxins (1.36). The death of turkeys from liver damage having been fed on groundnuts eontaminated with Aspergillus flavus led to the isolation of the highly carcinogenic aflatoxins. These developments are discussed in Chapter 9. It led to the awareness of the potential human health hazards from microbial metabolites and the implications of the presence of other mycotoxins in foodstuffs such as patulin in apple juice and the tri-chothecenes on corn. The development of analytical methods for the detection of mycotoxins has become an important aspect of food science. 

Two interesting metabolites of Penicillium patulum are patulin and penicillic acid. Their biosynthesis involves the cleavage of an aromatic ring. These substances are mycotoxins and their activity in this context is discussed in Chapter 9. 

F. tricinctum, which was isolated from turf that had undergone a yellow wilt, produced a good yield of T-2 toxin in the laboratory. Although these compounds are phytotoxic, they are better known as mycotoxins and are discussed in Chapter 9. 

Citrinin (9.22) is a widespread mycotoxin that is formed by many Penicillium and Aspergillus species, particularly P. citrinum, P. expansum and P. roqueforti. It was first isolated in 1931 by the Raistrick group and described as an antibiotic. It has been shown to have carcinogenic effects and to produce kidney damage. Evidence for its structure and biosynthesis is discussed in Chapter 4. 

The persistent chemical agents which could be used in a foodborne attack, aimed at poisoning human consumers, include the nerve agent VX, any of the mycotoxins—aflatoxin, T-2 toxin, nivalenol (see Appendix A for discussion of their toxicology)—and compounds such as ricin produced from the castor bean plant. Chapter 5 should be consulted for a full discussion on natural toxins. These chemicals, combined with the biotoxins listed above, could potentially be used in the food supply. This would not be an easy task since many of these agents are toxic to animals and thus might kill the host, preventing dissemination into the food distribution system. 

The following references support the general discussion of mycotoxin toxicology. I used these to illustrate foodborne poisons since I have worked with them in the past and have a firsthand familiarity with the literature. They are fully reviewed in the first text. 

This discussion focuses on the hemorrhagic T-2 mycotoxin, a highly toxic agent that causes several illnesses in humans and animals, as described. From the 1970s and 1980s, trichothecene mycotoxins surfaced in the press as bioterrorism warfare... 

Despite denials by the governments involved, the United States went public with charges that chemical warfare had been used in Southeast Asia and Afghanistan in 1980. Problems with the collection of samples and the remoteness of the sites, however, prevented definitive evidence from being obtained. Furthermore, the later identification, discussion, and media debate over the origin of possible trichothecene mycotoxins in Southeast Asia also took away a significant portion of the public interest in the alleged use of conventional chemical munitions. 

The pathological effects and clinical signs for many toxic materials can vary with the route and type (acute, single dose vs chronic, subacute doses) of exposure. For the trichothecene mycotoxins, however, a number of the toxic responses are similar, regardless of the route of exposure. As we discussed earlier in this chapter, once they enter the systemic circulation, trichothecene mycotoxins affect rapidly proliferating tissue regardless of the... 

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