Glycoalkaloids types

Assessment of whether a chemical has the potential to cause adverse effects in humans arises usually from direct observation of an effect in animals or humans, such as the acute poisoning episodes that have occurred when potatoes contain high levels of glycoalkaloids. Epidemiological studies have also been used to infer a possible relationship between intake of a particular type of food, or constituent of that food, and the potential to cause an adverse effect. Such observations led to the characterisation of the aflatoxins as human carcinogens. However, natural toxic substances that occur in plant foods have often been identified through observations in animals, particularly farm animals. It was observations of adverse effects in farm animals that led to the further characterisation of the phytoestrogens and the mycotoxins. In other instances, the concern arises from the chemical similarity to other known toxins. 

The Indians of the Peruvian Altiplano eat potatoes with a dip of clay and a mustard-like herb. They say the clay removes the bitter taste and prevents stomach pains or vomiting after eating large amounts of potatoes. The people who eat clay intend detoxication. This may explain how Indians started to utilize and domesticate wild potatoes. Indeed, experiments have shown that four different types of edible clay adsorb the glycoalkaloid tomatine under simulated... 

Arnqvist, L., Dutta, P. C., Jonsson, L., Sitbon, F. (2003). Reduction of cholesterol and glycoalkaloid levels in transgenic potato plants by overexpression of a type 1 sterol methyltransferase cDNA. Plant Physiol., 131, 1792-1799. 

Morris and Lee1 analyzed potato alkaloids on octyl and octadecyl-type stationary phases. Using a mobile phase consisting of acetonitrile - water that contained small amounts of etha-nolamine (less than 0.1%), detection at 200 nm was possible. The separation of a-chaconine and a-solanine could be achieved on an octadecyl column with acetonitrile - water - ethanol-amine (45 55 0.1)(Fig.10.9e) or on an octyl column with the same solvent in the ratio (55 45 0.l)(Fig,10.9f). The alkaloids could also be separated on silica gel with this mobile phase in the ratio (77.5 22.5 0.05)(Fig,10.9g). In the case when solanidine was present in the extracts, the silica gel column was preferred. Hydrolysates of the a-chaconine and a-solanine could also be analyzed with the octadecyl column (Fig.10.9a-d). The systems could also be used for the analysis of potato extracts (Fig,10.9e-g). For a total glycoalkaloid analysis, the normal-phase system gave the fastest results (Fig.10.9h). 

The glycoalkaloid -tomatine has been implicated in the resistance of tomato to both H. zea (4 10 18) and to L. decemllneata (8). q-Tomatine has been found in all Lycopersicon species surveyed (19, 20). It is present in both tomato foliage and fruit, although the concentration of -tomatine in the fruit decreases as the fruit matures (4, 10, 20). For at least two tomato species which have been examined (L esculentum and hlrsutum f. glabra turn), foliar K-tomatlne has been found associated with the leaf lamellae but not the tips of the type VI trlchomes (5, 21). 

In accordance with the nomenclature in this chapter the alkaloids veratrobasine, jervine, 11-deoxojervine (identical with cyclopamine), veratramine, verarine and the glycoalkaloids veratrosine, pseudo-jervine, and cycloposine belong to the bases of jervanine and veratra-nine type. 

Antifungal activity has been demonstrated mainly in two groups of plant steroids, glycoalkaloids of the Solanum type and saponins. Members of both groups are comprised of a steroidal aglycone... 

It should be noted that the sugar components of many glycoalkaloids that have been described as solanine have not been determined (36,61), and a reinvestigation using modern techniques, as for example paper chromatography, is necessary to determine the proper order and the type and number of monosaccharides. 

As can be seen from Table XLVI, results concerning production of glycoalkaloids in Solarium cell cultures are variable some authors were unable to detect the glycoalkaloids in cell cultures (e.g.. Ref. 760), others did find production of these compounds in various types of cell and tissue cultures. In fact, Zenk (76/) showed that cell clones of Solarium laciniatum may vary significantly in solasonine (48) content, ranging from 0 to more than 3% dry weight, with a clear maximum in frequency of occurrence at about 0.2%. 

Fig. 3.18 Chemotaxonomy and phylogeny of the Solanaceae. The provisional phylogenetic tree of Fig. 2.2 is shown here again though without terms for the clades in order to have a clear structure in favour of metabolite symbols. Plotted on the tree is the occurrence of three dominant and characteristic classes of secondary metabolites of the Solanaceae family with two subclasses in one case (I) Tropane alkaloids (two subclasses), (11) steroidal alkaloids/glycoalkaloids, (III) with-anoUdes/withasteroids. These metabolites are indicated by the following symbols. Co-occurrence of different classes (rather rare) is also indicated, i.e., by two corresponding symbols. Filled square tropane alkaloids of the structural types T5, T6, and T7-A - T7-B (very poisonous ester alkaloids with a tropic acid residue, e.g., hyoscyamine/atropine, scopolamine and their derivatives). Taxa highlighted by dt filled square may also show co-occurrence with tropane alkaloids of the following subclass according to Table 3.1 however, this is not highlighted in such cases. Open square tropane alkaloids of the structural types T1 - T4, T7-C, and T7-D (ester alkaloids of...

Pregnane Type Sapogenins/Saponins. 5a-Pregn-16-en-3P-ol-20-one was isolated from Solanum pimpinellifolium Jussl. sub nom. Lycopersicon pimpinellifo-lium (Jussl.) Mill, by Schreiber and Aurich (1966) and also by Bennett et al. (1967). The authors speculated that this aglycone could be a metabolite of the steroidal glycoalkaloid tomatine. Heftmann and Schwimmer (1972) added that... 

Table 7.3 Steroideil alkeiloids (atkamines) eilphabetically listed within the different structural types For 41 out of eiltogether 115 compounds from Solanum spp. (113 compounds), Lycianthes biflora, and Saracha punctata (one compound each) at least one corresponding glycoalkaloid was found and structurally elucidated, i.e., for 36% of the eilkamines also corresponding glycosides are known...

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