Legume quinolizidine

Voltage-gated K+ channels are critical to transmembrane potential- and Ca2+-mediated signalling. Voltage-regulated K+ channels are critically involved in action potentials as described above and such channels are blocked by the legume quinolizidine alkaloid sparteine (lupinidine) as well as by various synthetic psychoactive compounds with disparate effects such as amitryptiline, chlorpromazine, imipramine and phencyclidine. 

Both castanospermine and swansonine occur in some legume plants, such as Castanospermum australe and Swainsona canescens respectively. They are hybrid molecules compounded of pyrrohzidine and quinolizidine alkaloids, and have shown some resistance to the AIDS virus. Certainly, the above-mentioned alkaloids are also toxic for animals. 

Quinolizidine alkaloids are non-toxic to the legumes which produce them. On the other hand, the quinolizidine alkaloids can be toxic and in some cases very toxic to other organisms. The biotoxicity of alkaloids has for some time been considered to be connected with their bitter taste" ° ". The quinolizidine alkaloids are certainly bitter in taste to humans. However, not all alkaloids are. Literature states that some pyrrolizidine and indolizidine alkaloids are not bitter in their pure forms" Furthermore, there are many non-alkaloid compounds, such as flavonoids, that are bitter in taste but non-toxic. Therefore, although quinolizidine alkaloids are bitter, the connection between biotoxicity and bitter taste is not absolute. 

Alkaloids take part in the life processes of some invertebrates as pheromones, inducers of sexual behaviour, and in reproduction. A case study of quinolizidine alkaloids and population changes proved that these alkaloids occur in all legume species studied but not, however, in all individuals. The distribution and frequency changes of alkaloidal and non-alkaloidal plants in populations is a direct expression of natural selection natural hybridization and micro-evolution can be considered as an evidence of current evolutionary responses by ecological and genetic systems. 

Aniszewski, T. 1994. The biological basis of quinolizidine alkaloids. Science of Legumes, 1 1-24. 

Cheek, P. R. and Kelly, J. D. 1989. Metabolism, Toxicity and Nutritional Implications of Quinolizidine (Lupin) Alkaloids. In Recent Advances of Research in Antinutritional Factors in Legume Seeds Animal Nutrition, Feed Technology, Analytical Methods. Proceedings of the First International Work shop on Antinutritional Factors ANF) in legume seeds. November 23-25, 1988 (Huisman, J., Poel, T. F. van der and Liener, I. E. eds.), pp. 189-201. Agricultural University, Wageningen. 

Aniszewski, T. 1993. Lupine A Potential Crop in Finland. Studies on the Ecology, Productivity and Quality of Lupinus spp. PhD thesis. University of Joensuu, Joensuu and, Aniszewski, T. 1994. The biological basis of quinolizidine alkaloids. Science of Legumes, 1 1-24. 

Unique subcellular compartmentation is also present in quinolizidine alkaloid biosynthesis, which occurs in the mesophyll chloroplasts of some legumes.158 One of the enzymes catalyzing the last two acylations of the pathway in Lupinus albus occurs in the cytoplasm, whereas the other resides in the mitochondria/59 Although the quinolizidine nucleus appears to be synthesized in the chloroplast, subsequent modifications can occur only after alkaloid intermediates are transported to the cytosol and mitochondia. Quinolizidine alkaloids appear to accumulate in vacuoles of epidermal cells where their defensive properties are most effective. 

Sparteine 115 and lupanine 116, containing a tetracyclic bis-quinolizidine ring system, are alkaloids of the legumes (Fabaceae) species of lupin (Gems Lupinus) and broom (genus Cytisus, Sarothamnus, Genista). Sparteine 115 has been used in the management of cardiac arrhythmias [61]. 

Our knowledge of secondary compounds is limited mostly to those that are accumulated, but, in some instances, compounds normally not thought to be present have been found at very low levels. For example, azetidine-2-carbox-ylic acid, normally found in the Liliaceae and in some legumes, has been isolated from amino acid fractions of sugar beets Beta vulgaris, Chenopodiaceae) isolated as a by-product of sugar manufacture. A number of other unusual amino acids also were isolated from the mixture. About 500 kg of these fractions is obtained from 10 tons of sugar beets (Fowden, 1972). The formation of quinolizidine alkaloids... 

Most of the legume species that have been introduced into tissue culture produce only small amounts of quinolizidine alkaloids (Ellis, 1988). 

Complex quinolizidine alkaloids are found in other legume genera, such as those in the genus Ormosia (tribe So-phoreae) (Fig. 30.10). In view of recent biosynthetic findings on the biosynthesis of other quinolizidine alkaloids, it seems possible that these alkaloids may be synthesized directly from four cadaverine units (Kinghom and Balandrin, 1984). 

In the aphid genus Acyrthyosiphon, two closely related species feed on legumes. Individuals of one species, A. pisii, develop well only when they feed on plants lacking quinolizidine alkaloids. Those of the second species, A. spartii, only develop when they feed on plants containing these alkaloids. This aphid actually appears to be attracted by sparteine (17) (Waller and Nowacki, 1978). 

Plants of the parasite Cuscuta reflexa (Cuscutaceae or Convolvulaceae) acquire quinolizidine alkaloids from the host Spartium junceum (Hartmann, 1991). The species Cuscuta reflexa and C. platyloba take up alkaloids from a variety of legume host plants, including Cytisus praecox, Chamae-cytisus hirsutus, Petteria ramentacea, md Spartium junceum (Baumel et al., 1994). 

Stermitz, F. R. and G. H. Harris, Transfer of pyrrolizidine and quinolizidine alkaloids to Castilleja (Scrophulariaceae) hemiparasites from composite and legume host plants, J. Chem. Ecol., 13, 1917-1925 (1987). 

Wink, M., T. Hartmann, L. Witte, and J. Rheinheimer, Interrelationship between quinolizidine alkaloid producing legumes and infesting insects Exploitation of the alkaloid-containing phloem sap of Cytissus scoparius by the broom aphid Aphis cytisorum, Z. Naturforsch., 37c, 1081-1086 (1982). 

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