The Trichothecenes

This review lists the trichothecenes recorded in the literature up to Dec. 2000, together with their sources, coupled with a summary of the pathways involved in trichothecene biosynthesis, an area in which significant advances have been made during the past decade. The review contains both macrocyclic trichothecenes ( macrocycles ), previously recorded to Dec. 1991 (7), and non-macrocyclic trichothecenes, previously recorded to Dec. 1995 (2, 3). Some omissions from these earlier lists have been included, and some errors corrected. 

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Bondy, G.S., and Pestka, J.J., Dietary exposure to the trichothecene vomitoxin (deoxyni-valenol) stimulates terminal differentiation of Peyer s patch B cells to la secreting plasma cells, Toxicol. Appl. Pharmacol., 108, 520, 1991. 

Chung, Y. J. et al. Up-regulation of macrophage inflammatory protein-2 and complement 3A receptor by the trichothecenes deoxynivalenol and satratoxin G. Toxicology 186, 51, 2003. 

Zhou, H. R., Yan D., and Pestka J.J. Differential cytokine mRNA expression in mice after oral exposure to the trichothecene vomitoxin (deoxynivalenol) Dose response and time course. Toxicol. Appl. Pharmacol. 144, 294, 1997. 

Zhou, H. R. et al. Lipopolysaccharide and the trichothecene vomitoxin (deoxynivalenol) synergistically induce apoptosis in murine lymphoid organs. Toxicol. Sci. 53, 253, 2000. 

Shima, J. et al., Novel detoxification of the trichothecene mycotoxin deoxynivalenol by a soil bacterium isolated by enrichment culture, Appl. Env. Microbiol., 63, 3825, 1997. 

Various sequence sources other than genes from the trichothecene biosynthesis pathway were used to set up PCR-based systems for identification and detection of trichothecene producers. Highly specific... 

Kimura, M., Tokai, T., O Donnell, K., Ward, T. J., Fujimura, M., Hamamoto, H., Shibata, T., and Yamaguchi, 1. (2003). The trichothecene biosynthesis gene cluster of Fusarium grami-nearum F15 contains a limited number of essential pathway genes and expressed non-essential genes. FEBS Lett. 27,105-110. 

The isoprenoids contribute most to the list of structural similarities in the sea and on land. They range from common classes in both ecosystems, such as drimane sesquiterpenes, to rare classes in the sea, such as the trichothecenes (Chart 8.3.11). The similarity in marine and terrestrial polyether triterpenes (Chart 8.3.12) may be seen as convergence toward chemically favored structures, starting from squalene as a biosynthetic precursor. Similar conclusions may apply to polycyclic triterpenes. 

Tsang and Fraser-Reid effected an unusual ring-forming reaction during synthetic studies aimed at the carbon skeleton of the trichothecene group of terpenes (Scheme 16) [33]. 

The trichothecenes, a group of sesquiterpenes having a reasonably complex tricyclic structure, represent useful targets for the synthetic application of cyclohexadienyliron complexes. Several members of... 

A further method of determining the trichothecene mycotoxin deoxynivalenol in corn is based on DPP [33] and also on GC. 

The trichothecene framework 114 was constructed by interesting Pd-catalysed skeletal reorganization via pinacolone rearrangement of the allylic lactone 111. The exo-7r-allylpalladium complex 112 is attacked intramolecularly by a carbon bond (pinacolone rearrangement) to give 113 [60]. 

One of the metabolites of the trichothecene family of mycotoxins, termed "neosolanoil" (246) was isolated from Florunner peanuts and identified as 3a-hydroxy-4B, 8a-15-triacetoxy-12,13-epoxy trichothec-9-ene. This toxin was shown to be a potent plant growth inhibitor active to 10 % in the wheat coleoptile bioassay. 

It is not our intention to discuss all the data concerning the trichothecenes that are active against both plants and animals or to name them. They are metabolites of the fungi Acremonium, Cylindrocarpon, Dendrostilbella, Fusarium, Myrothecium, Trichoderma and Trichothecium, but only Cylindrocarpon, Fusarium, Myrothecium, and Trichothecium are considered phytopathogenic. And, as a further note, of 15 evaluated in the etiolated wheat coleoptile bioassay, all were significantly active (p< 0.01) to one degree or another, and the most active were the macrocyclic trichothecenes. Of the latter, verrucarin A and J, and trichoverrin B were highly potent. 

While an entire chapter could be written about the phytopathogenesis, the selective activity of the trichothecenes relative to specific plant genera, species, and cultivars, it is time to turn our attention to the mode of action of these unique secondary metabolites. 

Figure 28 Structures of Fusarium trichothecenes (including trichothecene intermediates isolated as natural products). The side chains (e.g., hydroxyl, acetyl, keto) are added to the trichothecene skeleton at C-3 (FT), C-4 (R2), C-15 (R3), C-7 (R4), and C-8 (R5), which are shaded in colors. While type A trichothecene has a single bond at C-8, type B trichothecene has a keto at C-8. Three rings that constitute the trichothecene skeleton [EPT R1 = (1), R2 = (1), R3 = (1), R4 = (1), R5 = (1)] are labeled A, B, and C in bold. It should be noted that EPT is not a Fusarium trichothecene.

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