Calystegines detection

Territories, contained the same complex of alkaloids [29], Recent experiments have also identified calystegines and swainsonine in the leaves of I. camea from Mozambique [40]. In contrast, calystegines were not detected in roots, leaves or seeds of I. tricolor and only trace amounts in seeds of I. alba [40], so that elaboration and accumulation of these alkaloids cannot be regarded as a general feature of the genus. 

The greatest number of plant species in which the calystegines have been detected belong to the family Solanaceae. This may partly be a reflection of the importance winch this family holds as a source of foodstuffs and medicinals to human society, so that once the alkaloids were discovered in one member of the family there was an incentive to search for them in other genera. 

The detection of calystegines in so many genera of the Solanaceae suggests that additional investigation of this plant family could prove fruitful, if only to attempt to define the subfamilies and tribes in which these alkaloids occur. However, caution should be exercised in adopting this approach due to the fact that calystegines also occur in the taxonomically disparate families Convolvulaceae and Moraceae. 

HPLC, using a reversed phase system consisting of a Zorbax NH2 column eluted with acetonitrile/water (4 1), was employed for the preparative separation of the calystegines [10], The lack of a chromophore renders the use of UV or fluorescence detection impossible without pre- or post-derivatization of the sample and the relatively low sensitivity of refractive index (RI) detection severely limits this technique for routine analysis. However, the rapid evolution of LC-MS methods may lead to their application in the future. 

HPLC analysis of calystegines is somewhat difficult due to their solubility and high polarity, which limit the selection of column packings and solvent mixtures. Moreover, their lack of chromophore excludes spectroscopic methods of detection without pre- or post derivatization of the samples. Gas chromatography on fused silica capillary column coupled with mass spectrometry is the most suitable analytical technique used for the determination of calystegines. However, the high polarity and the nonvolatility of the compounds preclude their analysis without derivatization and numerous derivatization reagents have been tested [9]. 

Occurrence in Non-solanaceous/Non-convolvulaceous Taxa. To date, the calystegines seem to be confined to altogether six plant families. They have been detected... 

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