Transformations of ascorbigen in vivo into ascorbigen acid and 1-deoxy-1-(indol-3-yl)ketoses

The products of the ascorbigen (ASG) in vivo transformation in mice after oral administration were studied by the HPLC method using previously characterized compounds obtained from ASG-ascorbigen acid {2-C-[(indol-3-yl)methyl]-α-l-xylo-3-hexulofuranosonic acid, ASG-acid}, 1-deoxy-1-(indol-3-yl)-α-l-sorbopyranose (Indsorbose) and 1-deoxy-1-(indol-3-yl)-α-l-tagatopyranose (Indtagatose) formed from the ASG-acid after decarboxylation and isomerization. The transformations of ASG were also studied in vitro in phosphate buffer at pH 7.4 or in bovine blood serum; in the latter case, opening of the lactone ring and decarboxylation proceeded faster than in the buffer solution. Invariably Indsorbose and Indtagatose were the major products formed from ASG. The same products were identified in the blood serum and liver of mice, which received ASG per os in a dose of 300 mg/kg. The levels of ASG and its degradation products in the blood serum and in the liver reached a maximum one hour after ASG administration. These data demonstrate that Indsorbose and Indtagatose are the abundant products of the ASG transformations in vivo and are identical to those formed in alkaline media and in serum in vitro.