Behavior of 3,4-endiol form of 2,3-diketo-gulono-delta-lactone formed from dehydro-L-ascorbic acid in deoxygenated and neutral solution.

The formation of L-ascorbic acid (AsA) was observed when dehydro-L-ascorbic acid (DHA) was dissolved in neutral buffer solutions under N2 bubbling at room temperature. The reduction of DHA was done with the lactonized compound of 2,3-diketo-L-gulonic acid (DKG), that is, the 3,4-endiol form of 2,3-diketo-gulono-delta-lactone (3,4-End DKGL). 3,4-End DKGL was formed from DHA or DKG (yield about 10%) under N2 bubbling in neutral buffer solution (pH 7.2). This material was not stable in neutral or alkaline solutions. 3,4-End DKGL suppressed more strongly the linoleic acid (LA) peroxidation in the medium containing 20% EtOH and 10 mM LA than did AsA. This may suggest the possibility that 3,4-End DKGL reproduces AsA from DHA in physiological status.