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

Abstract

Labeled tartaric acids from Pelargoniunt crispum apices which had been fed L-ascorbic acid-6-"C and Vitis labrusca and Parthenocissus inserta tissues which had been fed L-ascorbic acid-l-"4C 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.crispuom which had been labeled with D-glucose-l-"C or -6-'4C 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.All three stereoisomeric forms of tartaric acid have been found in higher plants; (+) TA' in numerous plant families (4) notably the Vitaceae and Geraniaceae (23, 24); (-) TA in Bauhinia reticulata (18) and as esters of caffeic acid in Cichorium intybus L., C. endivia L. and Lactuca sativa L. (6,21,22,30); and meso-TA as an ester of p-coumaric acid in spinach leaves and isolated spinach chloroplasts (16,25) or as an excreted product (5). Only the (+) form has received much attention as regards its metabolic origin. Literature pertinent to biosynthesis of (+) TA is summarized in recent publications (19,(27)(28)(29). These biosynthetic studies employed labeled precursors and, in most instances, recovered TA from solution as its poorly soluble KH salt. In one study (13,14), formation of (+) TA from glycolate-1-"C in Pelargonium zonale L. was accompanied by (-) TA and/or meso TA.This latter observation prompted a careful study of the isomeric form of labeled TA recovered from Pelargonium crispum L. after feeding L-ascorbic acid-6-4C (28) L-AA-6-'4C (28) and from Vitis labrusca berries and Parthenocissus inserta leaves which were labeled with L-AA-1-"4C (29) were used in this study. Samples from P. crispum apices which were labeled for 72 hr with D-glucose-1-"C or -6-"'C by the same procedure used in AA experiments (12) were also studied.Separation of Diastereomeric Forms of TA. Ion exchange chromatography with Dowex 1 (formate) resin and a 0 to 4 M formic acid gradient readily separated meso-TA from the chiral forms. With the two step gradient procedure described earlier (28), meso-TA appeared in the second step of the gradient in the volume eluted between 60 to 110 ml and chiral TA between 100 to 160 ml. Further purification by paper chromatography (28) and GLC (27) was used to identify TA.Resolution of Labeled TA. Samples used for this study had been recovered from plant extracts by ion exchange chromatography using (+) TA as carrier. Chiral TA fractions were combined and adjusted to pH 3.5 with KOH to recover the KH salt of TA. A weighed aliquot containing 0.05 to 0.1 1,Ci was converted to free TA and combined with an equimolar amount of (-) TA to make a racemic mixture. Following further dilution with unlabeled racemic TA, the mixture w...

Biosynthesis and Cellular Functions of Tartaric Acid in Grapevines

“…By feeding labeled Asc to immature berries of a number of species from the Vitaceae family it was determined that [1- 14 C]Asc and [4- 14 C]Asc corresponded to the C1 and C4 carbons respectively of the TA skeleton ( Williams and Loewus, 1978 ). Earlier studies that identified the key intermediates and organization of the C4/C5 pathway ( Saito and Kasai, 1969 ; Wagner and Loewus, 1974 ; Wagner et al, 1975 ) were complemented by later work identifying the final intermediates ( Saito and Kasai, 1982 , 1984 ). Accumulation of radiolabeled L-idonate in grapevine leaves also fed with labeled Asc confirmed that the oxidation of L-idonate to 5-keto-gluconic acid is a rate-limiting step of TA synthesis ( Malipiero et al, 1987 ).…”

Biochemical Symmetrization/ Desymmetrization of Organic Compounds: Dendrimeric Relationship with Molecular Formulas

“…Plants, especially higher plants, produce all three stereoisomeric forms of tartaric acid [19] (Fig. 1.a).…”

New Chemical Dualities Illustrated by Meso and C2 Symmetrical (CTS) Compounds

“…meso-tartaric acid [22,49,75,76], erythritol [77], butanediol [78], galactitol [26,79], allitol [80], xylitol [81], ribitol [82,83], allaric acid [84], xylaric acid [85], ribaric acid [86], galactaric acid [26], D-galactitol-3R,4Scinnamicacetal [87], galaoctitol [88][89][90].…”