Please, does anyone have information about Solasodine glycoalkaloids reaction with Ehrlich reagent? (+ve) or (–ve) why? (Mention a reference)
Ehrlich's reagent, prepared by dissolving 0.5--2.0 g of p–dimethylaminobenzaldehyde (DMAB) in 50 mL of 95% ethanol and 50 mL of conc. HCl is primarily used to identify indoles. Ehrlich's reagent is a strong electrophile which reacts with the electron-rich α-carbon of indole rings to form a blue-colored adduct. It is used to detect the presence of indole alkaloids. p-DMAB also reacts with hydrazine to form an azo-dye, which has a distinct yellow colou, hence used for spectrophotometric determination of hydrazine in aqueous solutions. The glycoalkaoilds -Solasonine and -solamargine have a trisaccharide attached to the secondary hydroxyl group of the aglycone solasodine. Ehrlich reagent is not reported to be used for qualitative detection of glycoalkaloids that may be due to their negative response to Ehrlich reagent. Qualitative detection of glycoalkaloids is generally done using Dragendorff’s reagents, Conc. H2SO4/MeOH, Molybdatophosphoric acid reagent, Paraformaldehyde reagent.
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