Toxins, alkaloids

Figure 2.11 Pyrrolizidine alkaloid toxins including (a) the pyrrolizidine nucleus, (b) retronecine, a less toxic monoester, and (c) jacobine, a highly toxic cyclic diester.

Figure 2.13 The indolizidine alkaloid toxin swainsonine (a potent inhibitor of a-mannosidase), responsible for locoweed toxicosis.

Podophyllotoxin (Fig. 4), a non-alkaloid toxin lignan, is a laxative, anti-tumor and antirheumatic agent. Cell cultures of Linum flavum were shown to be able to convert deoxypodophyllotoxin, a lignan isolated from Anthriscus sylvestris, into podophyllotoxin. ... 

Amphibians have mucus glands over their whole body to provide the mucus needed to keep their skin moist, and fields of granular glands that secrete alkaloid toxins. In addition to these general glands, salamanders possess glands... 

Powell RG, Petroski RJ, Alkaloid toxins in endophyte-infected grasses, Nat Toxins 1 163-170, 1992. 

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). 

Many alkaloids are toxic to foreign organisms. Toxicity is a secondary function of the alkaloids, because they are generally non-toxic to the organisms producing them. This is very important for understanding alkaloid nature. There are many studies on alkaloid toxins published in recent The... 

ASIDE Alkaloid toxins found in dendrobatid frogs... 

Al-Layl, K., Eoon, G., and Cod4 G. 1988. Isolation and purification of peptide and alkaloid toxins from Anabaena flos-aquae using high performance thin-layer chromatography. J Microbiol Meth 7, 251-258. 

A seventh novel alkaloidal toxin, pinnamine, was isolated and pnrified from the viscera of the Okinawan bivalve Pinna muricata (Takada et al. 2000). Its gross stmctnre, clarified by a detailed analysis of NMR and CD spectra, includes a 9-azabicyclo[4.2.1]nonane pharmacophoric element (Fig. 18.6A). Further synthetic studies have not only confirmed the absolute stereochemistiy of the molecule, but have also allowed stereocontrolled access to a non-natural congener, 5-epi-pinnamine, of the natural product (Kigoshi et al. 2001 Hjelmgaard et al. 2005). 

Piperidine alkaloid toxins, such as coniine, are structurally similar to nicotine, and contained in all parts of the plant. 

Acetylcholine receptors - muscarinic agonists There are a number of natural plant alkaloid toxins, including arecoline, muscarine and pilocarpine and green mamba snake peptides venoms, including MTl, MT2, MTS and MT4. 

Glycine ionotropic receptors - antagonists Plant alkaloid toxins include picrotoxin (active principle is picrotoxinin) and strychnine. 

Culvenor RA, Reed KFM, McDonald SE. Comparative levels of dimethyltryptamine-and tyraminerelated alkaloid toxins in Australian cultivars and some wild populations of Phalaris aquatica. Aust J Agric Res 2005 56( 12) 1395-403. 

Rivera Rentas, A. L., Rosa, R., Rodriguez, A. D., Escalona de Motta, G., (1995). Effect of alkaloid toxins from tropical marine sponges on membrane sodium currents. Toxicon 33, 491-497. 

New evidence has been presented that dart-poison frogs partially obtain the bioactive alkaloids secreted on their skin from their diet. For example, ants found in the tropics generate alkaloid toxins that are very similar to those found in poison frogs. 

The inactivation gate, h , can be selectively destroyed by the internal application of protease and chemicals such as the piperazinyl-indole derivative DPI 201-106 (Wang et al. 1990). Veratridine and batrachotoxin, alkaloid toxins, also inhibit inactivation and produce a steady-state depolarisation due to enhanced sodium permeability (Catterall 1980). At the cellular level, this results in a prolongation of the AP and positive inotropism. 

Apparently a frog itself does not produce the alkaloid toxin, for a frog kept in a controlled environment does not have the toxic alkaloid. It has been demonstrated that frogs get the toxins from the preys they eat, such as ants, termites, and flies, and they also seem to be able to modify the chemicals to make them more deadly. One of such preys has been identified as Choresine pulchra, a small beetle of about a rice grain size. As might be gathered from this description, similar alkaloids including batrachotoxin, have been found in some birds as well. 

Up to the year 2000 many reviews emerged that described the classes of naturally occurring polyamines and the research on their synthetic polyamine conjugates [1]. Recently, polyamine alkaloids, toxins, and polyamines in cancer therapy have been reviewed in detail [2,20-22]. In this review, we will group the polyamines considering their properties, and focus exclusively on the therapeutic appUcations of polyamine compounds that gained interest from 1996 until the present, as well as on the new advances in polyamine synthesis and modification using solid phase... 

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