Biodegradation of dehydro-l-ascorbic acid; 2,3-diketo-aldonic acid decarboxylase from rat liver

Kagawa, Yasuo; Mano, Yoshitake; Shimazono, Norio

doi:10.1016/0006-3002(60)90451-0

Cited by 12 publications

(6 citation statements)

References 5 publications

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“…Thus, GSH deficiency would be expected to produce effects that also result from deficiency of ascorbate and a-tocopherol. GSH deficiency decreases tissue ascorbate; that total ascorbate levels also decrease may be ascribed to metabolic degradation ofdehydroascorbate (34,58). Since a-tocopherol is maintained in reduced form by GSH (or ascorbate), the effect of GSH deficiency on a-tocopherol levels should be examined directly.…”

Section: Resultsmentioning

confidence: 99%

Glutathione deficiency decreases tissue ascorbate levels in newborn rats: ascorbate spares glutathione and protects.

Mårtensson

Meister²,

Mrtensson³

1991

Proc. Natl. Acad. Sci. U.S.A.

255

123

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Glutathione deficiency in newborn rats, produced by admiisttion of L-buthionine-(SR)-sulfoximine, a transition-state inactivator of y-glutamylcysteine synthetase, decreases ascorbate levels of kidney, liver, brain, and lung. These tissues, especially their mitochondria, undergo severe damage and the animals die within a few days. When glutathione levels are markedly decreased, ascorbate levels decrease leading to formation of dehydroascorbate, which is degraded. Ascorbate has high antioxidant activity, but it (and other antioxidants such as at-tocopherol) must be maintained in reduced forms. These studies show in vivo that an important function of glutathione is to maintain tissue ascorbate. Administration of large doses of ascorbate (but not of dehydroascorbate) to buthionine sulfoximine-treated newborn rats decreases mortality, leads to normal levels of ascorbate, and spares glutathione. Newborn rats given lower doses of buthionine sulfoximine develop cataracts that, as shown previously, can be prevented by giving glutathione monoester; as found here, such cataracts can be partially prevented by administration of high doses of ascorbate or dehydroascorbate. Ascorbate spares glutathione indicating that these compounds have similar antioxidant actions. Ascorbate may have reductive functions that are not efficiently performed by glutathione. Although glutathione normally functions to maintain ascorbate, a-tocopherol, and other cellular components in reduced states, ascorbate can serve as an essential antioxidant in the presence of severe glutathione deficiency.

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Section: Resultsmentioning

confidence: 99%

Glutathione deficiency decreases tissue ascorbate levels in newborn rats: ascorbate spares glutathione and protects.

Mårtensson

Meister²,

Mrtensson³

1991

Proc. Natl. Acad. Sci. U.S.A.

255

123

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“…In all species, initial metabolism involves the reversible conversion of ascorbic acid to dehydroascorbic acid; species' differences in the metabolism of ascorbic acid would appear to occur after this step. In the guinea pig and the rat, there is enzymatic delactonization of dehydroascorbic acid to diketogulonic acid (Kagawa et al, 1960(Kagawa et al, , 1962, which can then be decarboxylated to form carbon dioxide and a number of other compounds (Hornig, 1975). Carbon dioxide exhalation is the major route of elimination of ascorbic acid by the guinea pig and the rat.…”

Section: Figurementioning

confidence: 99%

Vitamin Tolerance of Animals

1987

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Download hundreds of free books in PDF • Read thousands of books online for free • Explore our innovative research tools -try the "Research Dashboard" now! • Sign up to be notified when new books are published • Purchase printed books and selected PDF files Thank you for downloading this PDF. If you have comments, questions or just want more information about the books published by the National Academies Press, you may contact our customer service department tollfree at 888-624-8373, visit us online, or send an email to feedback@nap.edu. This book plus thousands more are available at http://www.nap.edu.

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“…Although studies on biodegradation and biodeterioration started for more than a century, the first study on biodegradation registered in databases was published in 1960 (Kagawa et al, 1960) and since then 16,657 works have been referenced in scientific databases (ISI Web of Knowledge, 2011). Three years after this study, Borstlap and Kooijman (1963) addressed the problem of testing biodegradation with reference to anionic synthetic surfactants.…”

Section: Introductionmentioning

confidence: 99%

New Concepts in the Evaluation of Biodegradation/Persistence of Chemical Substances Using a Microbial Inoculum

Thouand¹,

Durand²,

Armand³

et al. 2011

Front. Microbio.

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The European REACH Regulation (Registration, Evaluation, Authorization of CHemical substances) implies, among other things, the evaluation of the biodegradability of chemical substances produced by industry. A large set of test methods is available including detailed information on the appropriate conditions for testing. However, the inoculum used for these tests constitutes a “black box.” If biodegradation is achievable from the growth of a small group of specific microbial species with the substance as the only carbon source, the result of the test depends largely on the cell density of this group at “time zero.” If these species are relatively rare in an inoculum that is normally used, the likelihood of inoculating a test with sufficient specific cells becomes a matter of probability. Normally this probability increases with total cell density and with the diversity of species in the inoculum. Furthermore the history of the inoculum, e.g., a possible pre-exposure to the test substance or similar substances will have a significant influence on the probability. A high probability can be expected for substances that are widely used and regularly released into the environment, whereas a low probability can be expected for new xenobiotic substances that have not yet been released into the environment. Be that as it may, once the inoculum sample contains sufficient specific degraders, the performance of the biodegradation will follow a typical S shaped growth curve which depends on the specific growth rate under laboratory conditions, the so called F/M ratio (ratio between food and biomass) and the more or less toxic recalcitrant, but possible, metabolites. Normally regulators require the evaluation of the growth curve using a simple approach such as half-time. Unfortunately probability and biodegradation half-time are very often confused. As the half-time values reflect laboratory conditions which are quite different from environmental conditions (after a substance is released), these values should not be used to quantify and predict environmental behavior. The probability value could be of much greater benefit for predictions under realistic conditions. The main issue in the evaluation of probability is that the result is not based on a single inoculum from an environmental sample, but on a variety of samples. These samples can be representative of regional or local areas, climate regions, water types, and history, e.g., pristine or polluted. The above concept has provided us with a new approach, namely “Probabio.” With this approach, persistence is not only regarded as a simple intrinsic property of a substance, but also as the capability of various environmental samples to degrade a substance under realistic exposure conditions and F/M ratio.

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Biodegradation of dehydro-l-ascorbic acid; 2,3-diketo-aldonic acid decarboxylase from rat liver

Cited by 12 publications

References 5 publications

Glutathione deficiency decreases tissue ascorbate levels in newborn rats: ascorbate spares glutathione and protects.

Glutathione deficiency decreases tissue ascorbate levels in newborn rats: ascorbate spares glutathione and protects.

Vitamin Tolerance of Animals

New Concepts in the Evaluation of Biodegradation/Persistence of Chemical Substances Using a Microbial Inoculum

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