D-isoascorbic acid

Fischer and Armstrong17 suggested the application of the benzaldehyde method for the decomposition of D-xylose phenylosazone, and a slight modification of this method180 was later employed in obtaining D-xylosone for the synthesis of D-isoascorbic acid,12-181-182 and L-xylosone182 for the... 

D-isoascorbic acid D-mannitol D-mannose D-quinic acid D-ribolactone D-ribose D-saccharic acid D-sorbitol L-sorbose D-xylose (—)-a-Pinene (+)-a-Pinene (—)-/ -Pinene (i )-(+)-pulegone... 

C6Hs06 D-Isoascorbic acid D-arabino-ascorbic acid4... 

S Wongyai. Separation of L-(+)-ascorbic and D-(—)-isoascorbic acids on multimodal phenylpropanolamine-coated silica. Chromatographia 38 609-612, 1994. 

As aforementioned, derivatives of Vitamin C and their analogs can function as hyaluronidase inhibitors. In particular L-ascorbic acid-6-hexadecanoate is a potent inhibitor (A. Botski, et al., pers. commun.). Vitamin C itself, D-isoascorbic acid, and dehydroascorbic acid are also inhibitors 262 Thus, some of the ability of Vitamin C to enhance HA deposition may be attributed to its inhibiton of hyaluronidase. 

Scheme 7.3 Carreira s total synthesis of ( + )-zaragozic add from D-isoascorbic acid.

Lactone 7 (derived from D-isoascorbic acid) reacted readily with the aryllithium formed from bromide 8 to produce lactol 9 (Scheme 16.3). The latter underwent a facile ring-opening and Wittig olefination with methylenetriphenylphosphorane to give 6 in excellent overall yield. After 0-trifLation, a two-carbon chain extension was performed on 10 with the azaenolate derived from A-cyclohexylacetaldimine 11 and lithium diisopropylamine (LDA). After acid hydrolysis of the product imine, aldehyde 12 was isolated in 83% yield for the two steps. The (2-azaallyl)stannane 5 was prepared from aldehyde 12 in quantitative yield by treatment with (aminomethyl)tri-n-butylstannane. 

Erythorbic acid is the same compound as D-isoascorbic acid, available from the Aldrich Chemical Company, Inc. This substance is also known as araboascorblc acid. 

L-ascorbic acid (Figure 9-9) is a lactone (internal ester of a hydroxycarboxylic acid) and is characterized by the enediol group, which makes it a strongly reducing compound. The D form has no biological activity. One of the isomers, D-isoascorbic acid, or erythorbic acid, is produced commercially for use as a food additive. L-ascorbic acid is readily and reversibly oxidized to dehydro-L-ascorbic acid (Figure 9-10), which retains vitamin C activity. This compound can be further oxidized to diketo-L-gulonic acid, in a... 

Araboascorbic acid d-araboascorbic acid D-2,3-didehydro-eryt ro-hexono-l,4-lactone E315 erycorbin d-erythorbic acid D-eryt ro-hex-2-enoic acid D-eryt ro-3-ketohexonic acid lactone glucosaccharonic acid D-isoascorbic acid isovitamin C y-lactone saccharosonic acid. 

The mean values of the L-ascorbic acid molecules and of D-isoascorbic acid are given for comparison. The values for Ca L-ascorbate dihydrate are weighed means of Refs. IS and 13. 

The fate of D-isoascorbic acid on oxidation has not yet been studied by diffraction methods, but NMR results (29) show that in inert solvents an asymmetric dimer is preferentially formed. In water, however, a mixture of two anomeric pyranose rings results, and the simple, reversible D-isoascorbic acid/dehydroisoascorbic acid equilibrium is lost. This may possibly be one of the factors that reduces the biological activity of D-isoascorbic acid. The latter has an effect that is only 5% of that of vitamin C (30),... 

NMR Spectroscopy and the Conformations of L Ascorbic Acid and D-Isoascorbic Acid in Aqueous Solution... 

Table VI. Proton—Proton Coupling Constants and ASe,( for L-Ascorbic and D-Isoascorbic Acids...

Figure 7. Newman projection viewed down the C5-C4 bond of D-isoascorbic acid.

The -isomer was prepared in the same manner starting from D-isoascorbic acid (III, 26 g). The 6-valerate ester of III was a syrup, and the yields of crude and pure crystals of the E-isomer were 8.1 g and 2.3 g, respectively. The mp of the pure material was 235-240°C (decomposed). 

We thank J. Dadok at the Camegie-Mellon NMR Facihty for Biomedical Studies for help in obtaining the 600-MHz NMR data, and National Institutes of Health for support of the Facility. We also thank Thomas C. Crawford and Glenn C. Andrews of Pfizer, Incorporated, for samples of 5-D-L-ascorbic acid and 5-D-D-isoascorbic acid and the Kansas State Agricultural Experiment Station for support of the campus NMR facility. 

Three stereoisomers of L-ascorbic acid were also bioassayed using the tobacco hornworm (Table I). Configurational changes at C4 and C5 aflFected activity and indicated that the geometry of C5 was more critical for activity than that of C4. The enantiomer, D-ascorbic acid, had approximately 40% activity, while the C5 epimer, D-isoascorbic acid, had 10% activity. The relative potency of those isomers is reversed in vertebrate and invertebrate animals. With D-isoascorbic, 2-10% activity in other insects was reported (20-22), but this compound did not promote development of the cotton leafworm (23). L-Isoascorbic acid had no activity in the hornworm or guinea pig. 

D-isoascorbic acid slightly active, dehydroascorbic acid fully active 21,22... 

Manduca sexta dietary requirement (0.5 mM) dehydroascorbic acid, Mg 2-0-phosphonoascorbate, Na 6-0-myristoylascorbate fully active D-ascorbic acid 50% active 6-bromoascorbic acid 20% active D-isoascorbic acid 10% active K 2-0-sulfoascor-bate, L-isoascorbic acid, L-gu-lonic acid y-lactone inactive 5... 

Myzus persicae dietary requirement, D-isoascorbic acid fully active 67... 

Na ascorbate, Ca ascorbate, l-dehydroascorbic acid active, D-isoascorbic acid inactive... 

L-ascorbic acid, D-isoascorbic acid, and L-dehydroascorbic acid inhibited progeny by producing diet nutritionally deficient in protein (browning)... 

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