Stereoisomeric Characterization of Tartaric Acid Produced during l-Ascorbic Acid Metabolism in Plants.

Labeled tartaric acids from Pelargonium crispum apices which had been fed l-ascorbic acid-6-(14)C and Vitis labrusca and Parthenocissus inserta tissues which had been fed l-ascorbic acid-1-(14)C were examined by chemical means to determine chiral configuration. In each instance, label was associated with (+)-tartaric acid.Similar experiments with labeled tartaric acid from P. crispum which had been labeled with d-glucose-1-(14)C or -6-(14)C led to the same result. No evidence was obtained for formation of labeled meso-tartaric acid in experiments described above. The recent suggestion of H. Ruffner and D. Rast (Z. Pflanzenphysiol. 73: 45-55, 1974) that conversion of l-ascorbic acid to tartaric acid in plants is a nonenzymatic process is re-examined in the light of present findings.