Convolvulaceae Family

Calystegines appear to be vddely distributed in the Convolvulaceae family [78,80]. Eich and coworkers focused on the occurrence of seven calystegines (A3, A5, Bi, B2, B3, B4, Cl) identified by GC-MS analysis with authentic samples as references and analyzed the extracts of 65 Convolvulaceae species from predominantly tropical 

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Wagner H (1973) The Chemistry of Resin Glycosides of the Convolvulaceae Family. In Bendz G, Santensson J (eds) Medicine and Natural Sciences. Chemistry in Botanical Classification. Academic Press, New York, p 235 12. Mannich C, Schumann P (1938) Uber Jalapenharz und dessen Hauptbestandteil, das Con-volvulin. Arch Pharm Ber Dtsch Pharm Ges 276 211... 

The detection of cycloclavine (11 cieHi8N2 mp 166° [a]D +63° in chloroform) in the seeds of plants of the Convolvulacea family was surprising. In Ipomoea hildebrandtii Vatke it occurs in quantities up to 0.2%, accompanied by traces of festuclavine (14). 

Fig. 5.8 Structures of nortropanes from the Solanaceae and Convolvulaceae families.

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]. 

Unusual pyronotropane tropane alkaloids have been fotmd in the family Proteaceae. Tropine and pseudotropine esters of benzoic acid have been isolated from the family Euphorbiaceae. Novel dithiolane esters, along with tropine esters of acetic, propionic, n-butyric, isobutyric, isovaleric, and benzoic acids have been fotmd in the Rhizophoraceae. Calystegines, as well as a 3-hydroxybenzoate ester, have been fotmd in Brassicaceae. The calystegines have been used as chemotaxonomic markers in the Convolvulaceae family [20]. Tropine esters with methoxy-substituted benzoic acids are also characteristic for the later family. 

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. 

Our knowledge of the occurrence and distribution of tropane alkaloids in the Convolvulaceae family is based on (i) the isolation and structure elucidation of Convolvulaceae-specific metabolites (T3, T4, T6-A, T6-B, T9) and (ii) extensive GC/MS data. This analytical method is of remarkable advantage due to its high resolution and sensitivity. Thus, even very low concentrations of a metabolite can be identified unequivocally. 

Alkaloids like (glycine)betaine and trigonellin represent widely distributed minor constituents of angiosperms (Blunden et al. 2(X)5). In the Convolvulaceae family at least one of these two betaines has been detected in the vegetative epigeal parts... 

Table 8.2 Occurrence of structurally (at least almost completely) elucidated resin glycosides and glycosidic acids, respectively, in the Convolvulaceae family Convolvulaceae-based trivial names of hvdroxv fatty acids (HFAl ... 

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