Convolvulaceae calystegines found

Both alkaloids have (+) and (-) forms but only the (-) hyoscyamine and (-) scopolamine are active. The biosynthetic pathway of tropane alkaloids, Fig. (1) is not totally understood, especially at the enzymatic level. Edward Leete has pioneered the biosynthetic studies of tropane alkaloid since 1950"s using whole plants and isotope labels [85-86]. The tropane alkaloid hyoscyamine is bioconverted by the enzyme H6H (hyoscyamine 6p-hydroxylase, EC 1.14.11.11) to scopolamine via 6p-hydroxyhyoscyamine. Hyoscyamine is the ester of tropine and (S)-tropic acid. The (S)-tropic acid moiety derives from the amino acid L-phenylalanine, while the bicyclic tropane ring derives from L-omithine primarily or L-arginine via tropinone. Tropinone is stereospecifically reduced to form either, tropine which is incorporated into hyoscyamine, or on the other hand into pseudotropine which proceeds to calystegines, a group of nortropane derivates that were first found in the Convolvulaceae family [87]. 

However, at least one group of subclass B type metabolites, namely Tl-type tropane alkaloids as well as calystegines (see Sect. 3.5) represent plesiomotphic characters since both are also metabolites of the Convolvulaceae family. Such metabolites are found throughout the family. Obviously, they are the basis for apomorphic developments. 

Table 3.9 Distribution of the most frequent calystegines in the Convolvulaceae including species found negative data from Schimming et al. (1998, 2005) if not indicated otherwise...

Calystegines have been identified in the plant families Convolvulaceae, Solanaceae, Moraceae and Brassicaceae and have been found in numerous edible fruits and vegetables, especially members of the Solanaceae family, such as potatoes, tomatoes, eggplants and sweet and chili peppers, but also in mulberries and some Brassica vegetables and spices, such as kohlrabi, Brussel sprouts and black mustard leaves. 

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