Amines toxins from

An example that starts the synthesis of polyamine toxins from a central amino group is shown in Scheme 13 [229,230]. The backbone is elongated by alternate coupling of benzyl-protected amines and bromides. Due to the protection group strategy consisting of orthogonal Boc- (128), benzyl- (138), and phthalimides (137) it is possible to synthesize polyamines from center to tail. Unfortunately, after three alkylation steps the overall yield is only 30%, which drops the overall yield to 10-30%. 

Coelenterates and Echinoderms. Coelenterate and echinoderm toxins range from small molecular weight amines, to sterols, to large complex carbohydrate chains, to proteins of over 100,000 daltons. Molecular size sometimes reflects taxonomy, e.g., sea anemones (Actiniaria) all possess toxic polypeptides varying in size from 3,000 to 10,000 daltons while jellyfish contain toxic proteins (ca. 100,000 daltons). Carotenoids have been isolated from Asterias species (starfish), Echinoidea (sea urchins), and Anthozoans such as Actiniaria (sea anemones) and the corals. These are sometimes complexed with sterols (J5). 

Leucaena spp. contain mimosine, which is degraded to 3-hydroxy-4(l//)-pyridone (3,4-DHP see Section 2.2.4 for more detail). Leucaena, while toxic to unadapted ruminants, is a good source of protein and minerals for many livestock species in some countries. However, if Leucaena is ingested as 50% or more of the diet it will depress growth, cause hair loss, and reduce reproductive performance. Mimosine is a toxin that animals may become adapted to. Ruminal adaptation can be transferred from animal to animal, suggesting a specific set of rumen organisms are capable of detoxifying this amine. 

Psilocybin (Figure 3.5a) and psilocin (Figure 3.5b) are indole derivatives substituted in position 4 by a hydroxyl group, where psilocybin is phosphory-lated. Due to its ionic properties, psilocybin is soluble in water. In addition, phosphorylation protects psilocybin from oxidative degradation. Both compounds are found to affect laboratory animals, but there is evidence that only the dephosphorylated form, psilocin, is the active species. In their structure the toxins resemble serotonine, a biogenic amine known to be a neurotransmitter. 

Alkaloid Toxins. Only one alkaloid toxin has been chemically defined from the cyanobacteria. This is the secondary amine, 2-acetyl-9-azabicyclo (4-2-1) non-2-ene, called anatoxin-a. It is isolated from the filamentous strain Anabaena flos-aquae NRG-44-1 (18,19). 

International Agency for Research on Cancer (lARC) (1993). Toxins derived from Fusarium moniliforme Fumonisins Bi and Bz and Fusarin C. In "lARC Monographs on the Evaluation of the Carcinogenic Risks to Humans Some Naturally Occurring Substances Food Items and Constituents, Heterocyclic Aromaotic Amines and Mycotoxins," vol. 56, pp. 445 66. International Agency for Research on Cancer, Lyon, France. 

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