Ascorbigen - Occurrence, Synthesis, and Analytics

Ascorbigen (2-C-(3-indolyl)-methyl-α-L-xylo-hex-3-ulofuranosono-1,4-lactone, 1) is a breakdown product of glucobrassicins found in cruciferous vegetables, such as cabbage, cauliflower, Brussel sprouts, or broccoli, formed by direct C-alkylation of ascorbic acid (vitamin C) by (3-indolyl)-methyl intermediates under physiological conditions. It is a labile compound, and direct synthesis approaches are hampered by the oxidative instability of the indol moiety and ring transformations of the ascorbyl part. The latter have also impeded ascorbigen analytics for decades, and only recently different ascorbigens have been shown to represent mixtures of compounds rather than individual ascorbigen-type compounds. Following a review of pertinent literature, timely aspects of ascorbigen chemistry, including the most recent synthesis approaches and in-depth characterization of the compound, are presented.