Steroidal alkamines

Solanum steroid alkaloids have been isolated so far from nearly 350 species of the plant families Solanaceae and Liliaceae, in which they generally occur as glycosides. All of the 75 known steroidal alkamines of the Solanum type,... 

The most significant chemical progress in the last decade has been the isolation and structural elucidation of an increasing number of new steroidal alkamines and glycosides the structures of which, however, still belong to one of the known types 1-5. Extensive work has also been directed to a number of new partial and total syntheses as well as to the degradation of the alkamines, particularly to pregnane derivatives. A number of review articles have been published in the last years (e.g., 31-38). 

Fig. 7.20 Three types of steroidal alkamines with two basic centres and their occurrence in the genus Solarium. Highlighted in grey, cyclohemiketal moiety (fuU ketal -OCH or -OCH CH instead of -OH examples in Table 7.3). Dotted lines separate the respective structures given together with their trivial and/or chemical names (above) from the structurally related 5,6-dehydto congener in case of 3-aminospirosolanes and from corresponding isomers in case of 3-amino-22,26-epiminocho-lestanes (below). The 5,6-dehydro derivative of solanocapsine, solanoforthine, is another constituent of S. seaforthianum demonstrating the co-occurrence of different structural types...

Fig. 7.21 Unusual structural types of steroidal aLkamines. Wavy lines indicate unknown configuration. Highlighted in grey oxygen instead of nitrogen in other structural types. Dotted lines separate structures given together with their trivial names (above) from structurally related congeners (below)...

Table 7.6 Distribution and frequency of steroidal alkamines (aglycones) in the series of sect. Petota Dumort (genus Solanum)... 

These steroidal alkamines were detected predominantly after acidic hydrolyzation of the corresponding glycoalkaloids demissine (demissidine-based), solanine/chaconine (solanidine-based), and tomatine (tomatidine-based), respectively... 

For further alkaloids from S. lycopersicum (A-nitrosotomatidine), S. pimpinelli-folium (pimpifoUdines), and unique steroidal alkamines from the hybrid S. lycopersicum X S. hirsutum see Table 7.3. These metabolites may represent autapomorphic characters. 

Species Steroidal alkamine Steroidal sapc enin References... 

For the quantitative determination of Solarium alkaloids in plant materials some new methods have been developed for instance, gravimetric procedures using the afore-mentioned cholesterol precipitation (15) for tetraosides, especially with saturated aglycones volumetric methods with titration of the bases in water-free solvents using aromatic sulfonic acids (26c, 47, 48) a number of simplified spectrophotometric methods by applying the Clarke reaction (49), that is, the hlue color obtained with paraformaldehyde-phosphoric acid in the case of J -unsaturated steroid alkamines and their glycosides (12, 50-52a, 525), or with the aid of amphi-indicators of the tropaeolin type (52,53-57,57a). The well-known Liebermann-Burchard reaction is not applicable to nitrogenous 3 -hydroxy-J -steroids (55). ... 

Similar to that of steroids, the biosynthesis of these polyol alkamines occurs through acetate and mevalonate (Goseva et ai, 1960). 

The more common and more exhaustively investigated alkamines of the Solanum group on selenium dehydrogenation have yielded the typical steroid dehydrogenation product, namely 7-methylcyclopentenophen-anthrene. The nitrogen in these degradations appears in the form of... 

The alkamines isolated directly from plant material or obtained by acid or enzymatic hydrolysis of naturally occurring glycosides between 1967 and 1979 are summarized in Table III. Physical me ods are of increasing importance in structure elucidation. Recent papers have dealt with IR spectra (173), H NMR (174,175), NMR (176-178,357,358), EPR (179), ORD (180-183), and MS (184,351,352) of Solanum alkamines. Some X-ray analyses have been carried out since 1967 (58, 81, 149, 185-189, 359). Tables rV-VI survey the characteristic features of H NMR, NMR, and MS of Solanum alkaloids. Silver nitrate-containing adsorption layers were shown to be useful in TLC separation of 5a-saturated and S-unsaturated alkamines (194,195). High-pressure liquid chromatography has been applied successfully for the separation of steroidal Solanum and Veratrum alkamines (373). 

Co-occurrence of Steroidal Sapogenins/Saponins and Alkamines/Glycoalkaloids... 

Table 7.3 Steroidal alkaloids (alkamines) alphabetically listed within the different structural types For 41 out of altogether 115 compounds from Solarium spp. (113 compounds), Lycianthes biflora, and Saracha punctata (one compound each) at least one corresponding glycoalktiloid was found and structurally elucidated, i.e., for 36% of the alkamines also corresponding glycosides are known (continued)...

Occurrence in Non-solanaceous Taxa. Steroidal alkaloids with an intact alka-mine skeleton (sometimes called Solamm alkaloids ) as metabohtes of the plant kingdom are confined to the Solanaceae and to the Liliaceae s.l. (including Melanthiaceae), respectively. In spite of the fact that they are not related (nested within the eudicots and the monocots, respectively) these two famihes share the occurrence of a few alkamines, e.g., solanidine, solasodine (see different footnotes of Table 7.3). 

Thus, it may be assumed, that steroidal alkaloids, i.e., alkamines and/or glycoalkaloids, represent a common and consistent ttait in the genus Solarium. This was already assumed by Heftmann (1983) ( It is quite possible that they occur in all representatives of this genus ) and Hegnauer (1990) Solatium alkaloids are hardly absent in any species of the genus . 

In 1961 Meyer and Bernoulli (135) reported the isolation of a new steroid alkaloid, paniculidine, and its glucoside, paniculine, from roots of the Brazilian Solanacea S. paniculatum. Paniculidine was accompanied by a minor alkamine (Substance Ai) which seems to occur with its glycoside (Substance C). Paniculidine was regarded as having the empirical formula C26H43NO3, a primary amino group, and was shown to give a N monoacetyl derivative but a structure has not been proposed. 

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