Study of natural ascorbigen and related compounds by HPLC

Abstract The effect of processing of vegetables on ascorbigen formation, the ultimate fate of its transformation, their pharmacological evaluation are areas requiring detailed study using analytical methods capable of measuring various individual components. A reversed-phase chromatographic system for separation of ascorbigen, which is an indole containing a derivative of l -ascorbic acid, and its synthetic analogs with different substituents in the indole nucleus was developed. The isocratic chromatographic system was also developed for separation of ascorbigen and its transformation products in acidic media. Ascorbigen B which was previously described as the 2-epimer of natural ascorbigen was shown by HPLC to be a mixture of compounds, where natural ascorbigen ‘dimer’ was the major component, and natural ascorbigen and its ‘trimer’ were the minor components. To determine the content of ascorbigen and its transformation products in extracts of fresh or sour cabbage a reversed-phase chromatographic system with gradient elution was developed, with l′-methylascorbigen as an internal standard. Extracts of fresh or sour cabbage contained the ascorbigen (2·4–5·5 mg per 100 g fresh weight), as the major component and ascorbigen ‘dimer’ (0·1–0·3 mg per 100 g fresh weight), ascorbigen ‘trimer’ (0·1–0·3 mg per 100 g fresh weight), 3-hydroxymethylindole (0·2–0·3 mg per 100 g fresh weight) and (indole-3-yl)acetonitrile (0·1–0·5 mg per 100 g fresh weight) as the minor components.