Of quinolizidine alkaloids

Mass spectral data have also been employed for biological studies aimed at determining the distribution of quinolizidine alkaloids within a plant. For instance, the analysis of stem sections of Lupinus polyphyllus and Cytisus scoparius by laser desorption mass spectrometry led to the conclusion that these alkaloids are restricted to the epidermis and probably also to the neighboring one or two subepidermal cell layers <1984MI230>. 

Two-dimensional thin-layer chromatography (TLC) with adsorbent gradient has allowed the separation of quinolizidine alkaloids in the herb and in several alkaloids from Genista sp. <2004MI89>. 

The high-performance liquid chromatography (HPLC) determination of quinolizidine alkaloids in Radix Sophora flavescens was assisted by using tris(2,2 -bipyridyl)ruthenium(n) electrochemoluminescence <2004MI237>. Tandem HPLC-MS techniques have allowed the development of a sensitive and specific method for the determination of sophocarpine, matrine, and sophoridine in rabbit plasma <2005MI1595>. 

A review has appeared regarding the infrared and nuclear magnetic resonance spectroscopic investigations of quinolizidine alkaloids (303). The connection between the C/D ring junction and the existence of Bohlmann bands in the IR spectra of indolo[2,3-a]quinolizidines has been reinvestigated and interpreted (304). 

The common structural feature of quinolizidine alkaloids is a decalin ring system with a nitrogen at one vertex. Often a second or third nitrogen atom is... 

Carey, D.B. and Wink, M. (1994). Elevational variation of quinolizidine alkaloid contents in a lupine Lupinus argenteus) of the Rocky Mountains, J. Chem. EcoL, 20, 849-857. 

Wink, M. and Carey, D.B. (1994). Variability of quinolizidine alkaloid profiles of Lupinus argenteus (Fabaceae) from North America, Biochem. Systematics EcoL, 22, 663-669. 

Wink, M., Meibner, C. and Witte, L. (1995). Patterns of quinolizidine alkaloids in 56 species of the genus Lupinus, Phytochemistry, 38, 139-153. 

The biochemistry and physiology of quinolizidine alkaloids is reviewed with respect to their role in lupin meteibolism. Minor roles of the alkaloids may be nitrogen transport and nitrogen storage, but their main function is that of chemical defense. 

Table I. Inhibitory Concentration of Quinolizidine Alkaloids on Various Organisms...

Table II. Concentrations of Quinolizidine Alkaloids in Parts of Plants...

Figure 7. The raw extraction of quinolizidine alkaloids from different lupine species in the Research and Teaching Laboratory of Applied Botany of the University of Joensuu (Photo T. Aniszewski). Observe the different colours of the raw extracts, which signifies different concentrations of alkaloids in different species.

The synthesis pathway of quinolizidine alkaloids is based on lysine conversion by enzymatic activity to cadaverine in exactly the same way as in the case of piperidine alkaloids. Certainly, in the relatively rich literature which attempts to explain quinolizidine alkaloid synthesis °, there are different experimental variants of this conversion. According to new experimental data, the conversion is achieved by coenzyme PLP (pyridoxal phosphate) activity, when the lysine is CO2 reduced. From cadeverine, via the activity of the diamine oxidase, Schiff base formation and four minor reactions (Aldol-type reaction, hydrolysis of imine to aldehyde/amine, oxidative reaction and again Schiff base formation), the pathway is divided into two directions. The subway synthesizes (—)-lupinine by two reductive steps, and the main synthesis stream goes via the Schiff base formation and coupling to the compound substrate, from which again the synthetic pathway divides to form (+)-lupanine synthesis and (—)-sparteine synthesis. From (—)-sparteine, the route by conversion to (+)-cytisine synthesis is open (Figure 51). Cytisine is an alkaloid with the pyridone nucleus. 

The first method of alkaloid analysis was developed in 1805, in the case of morphine. This method of isolation, with minor and major variations, is still used today. By this method, the first quinolizidine alkaloids were also extracted sparteine in 1851, lupinine in 1865 and lupanine 2 years later. At the beginning of the 20th century, the extraction and determination of total quinolizidine alkaloids in the same analysis (common) was carried out by Jurkowski , Nowotndwna, Trier272, ivanov °, Sengbusch , Lukaszewicz , Wuttke . Reifer and Niziolek and Wiewiorowski and Skolik initiated research in which the sum of the contents of the different and separate alkaloids is the total alkaloid content. The method of isolation of quinolizidine alkaloids was developed next by Wysocka et and Wysocka and Przybyl . ... 

Alkaloid analytical methods were developed by applications based on different hypotheses, from the simple to the very complicated. Subsequently, corresponding instruments were developed. This development can be seen by considering the example of quinolizidine alkaloids. 

Enzyme-linked immunosorbent assay is a heterogenous immunoassay. Reactions involve a solid phase to which components are sequentially presented and successively bound. This method is very effective in the determination of the total alkaloid content. The positive characteristics of this method are the use of non-toxic reagents and basic equipment with low costs, a small sample volume and the ability to measure alkaloids in crude sample extracts. According to the literature, compared with results obtained from GLC, the precision of ELISA for quinolizidine alkaloids is not as high as that of the gas chromatography procedure, but is adequate for plant breeding purposes. The use of enzymes in developing the methods of quinolizidine alkaloids analysis looks likely to increase in the future. 

There exists a long list of different methods of quinolizidine alkaloid analysis (Table 21). These methods are of a chemical and biological nature. The development of methods of alkaloid analysis has been a long and difficult process. 

A further problem which must be resolved is the resistance of quinolizidine alkaloids to other amines and nitrogen compounds during the analysis. The general conclusion is that a perfect method of alkaloid analysis does not exist. Therefore, the explanation of results in the light of the above-mentioned factors is vital in each case. 

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. 

One can find a number of methods of quinolizidine alkaloid extraction within existing literature. The most frequently applied methods are extraction by alcohols (50% methanol or 96% ethanol, or these alkaloids with a 1% addition of glacial acetic acid). 

Wysocka and Przybyl presented an efficient extraction method of quinolizidine alkaloids. The authors themselves developed and investigated this method, in which includes the following steps of extraction ... 

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