Alkaloids of the Genera Solanum and Lycopersicum

Compounds hi / Colour reaction with SbCla- reagent (No. 15)  

ScHRBiBBB et al. have also used TLC often in elucidating the constitution of Solanum alkaloids. They have reported good separations in more than 17 articles and their experience in TLC is summarised in a special publication [206]. The layers recommended are 1. silica gel 6 (Merck) 2. silica gel 6, sprayed with 10 % silver nitrate solution 3. silica gel (anhydrous, pure, Firm 88) + 10% gypsum 4. alumina according to Bbockmann, +10% gypsum. Solvents preferred are  

Detection is carried out with cerium (IV) stdphate (Bgt. No. 37). It cannot be used with layers impregnated with silver nitrate, nor with alumina layers. Iodine vapour or solution (Rgt. No. 143) or para-formaldehyde-phosphoric acid (Rgt. No. 194) can be used also and 2,4-dinitrophenylhydrazine (Rgt. No. 82) with alkaloids containing a keto group. The cerium (IV) sulphate reagent is recommended as a universal detection agent zl -unsaturated compounds yield a colour reaction even in the cold. Iodine vapour permits non-destructive detection of the sterol alkaloids, so that they may be subsequently isolated unchanged. 

Solanidine and demissidine can be separated on a silver nitrate-impregnated silica gel layer. Schbeibeb et al. [207 b] have used TLC also for preparative separation of Solanum alkaloids. Using 8 solvents on silica gel G layers, Paqijin and Lepage [158] have separated the three principal alkaloids from Solanum tuberosum, i. e., solanine, chaconine and solanidine. Antimony(III) chloride reagent was used for visualisation. P bez-Medina et al. [164] have investigated many Solanum species in the search for a raw material source of solasodine. They used TLC on silica gel 6 with n-butanol-methanol-diethylamine (85 + 5 + 10) as solvent and antimony(III) chloride (Rgt. No. 16) for visualisation. The TLC of this alkaloid class is described in other publications [2, 25, 183, 208]. 

LiBiiEB and CebnI [117] have undertaken a detailed investigation of the TLC of these alkaloids and their derivatives. They separated on silica gel G layers, using benzene or ether, saturated with ammonia. The Dragendorff reagent served for visualisation. Conclusions about constitution and stereochemistry of the compounds could be drawn from the jB/-values. 

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