Correlations of tissue oxypurine levels with xanthine dehydrogenase changes in the chick

The existence of uric acid in mammalian brain was recently reported, but it has not yet become a consensus. The mammalian brain has been thought to lack xanthine oxidase, which catalyzes hypoxanthine to xanthine and xanthine to uric acid as the last steps of ATP degradation in other tissue. Using high-performance liquid chromatography, we performed assays for hypoxanthine, xanthine, and uric acid in rat brain after cerebral ischemia. It was confirmed that all three substances showed significant augmentation in the removed brains and that the chronological order of those increases corresponded to the order in the metabolic pathway. Allopurinol, a specific inhibitor of xanthine oxidase, significantly suppressed the increases in uric acid and xanthine, and a compensatory accumulation of hypoxanthine was observed. From these results, it was concluded that uric acid does exist in the brain, increases after ischemia, and is possibly the end product of purine degradation in the brain. Furthermore, it is suggested that xanthine oxidase exists in the brain and catalyzes the reaction from hypoxanthine to xanthine and then to uric acid. These reactions catalyzed by xanthine oxidase are considered to be a source of free radicals and may play important roles in the pathogenesis of cerebral ischemic injury. (Neurosurgery 25:613-617, 1989)

Hypoxanthine

Allopurinol

Xanthine

Xanthine dehydrogenase

Xanthine oxidase inhibitor

10.1227/00006123-198910000-00016

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Citations (29)

The production of diazotizable amines by a simple degradative reaction of purines

Archives of Biochemistry and Biophysics (1952)

S. Friedman Joseph S. Gots

Hypoxanthine

Purine metabolism

Xanthine

10.1016/0003-9861(52)90332-9

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Citations (12)

THE EFFECT OF ALLOPURINOL ON CEREBRAL SPINAL FLUID (CSF) PURINES IN HYPOXANTHINE-GUANINE PHOSPHORIBOSYL TRANSFERASE DEFICIENCY SYNDROMES: 58

Pediatric Research (1985)

N. Lawrence Edwards Juan Puig F Mateos

Allopurinol

Hypoxanthine

Xanthine

Lesch–Nyhan syndrome

Purine metabolism

10.1203/00006450-198507000-00078

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Citations (0)

Stimulatory Effects of Purines on Flavinogenesis by Non-Growing Cell of Eremothecium ashbyii

THE JOURNAL OF VITAMINOLOGY (1972)

Hisateru Mitsuda Kenji Nakajima

Purine metabolism in relation to the riboflavin biosynthesis was examined using non-growing cell of Eremothecium ashbyii.1. It was found that xanthine is the most effective purine for flavinogenesis among various purines tested in the stimulation experiments using non-growing cell.2. The UV light absorption spectra of purines in non-growing cell medium were determined during the incubation. The conversions of adenine to hypoxanthine at the earlier stages and hypoxanthine to xanthine at the later stages were detected. Furthermore, the conversion of adenine to hypoxanthine was found to be located endogenously.3. The membrane transportable effects of purines were examined by photometrically determining the residual purines in the medium during the incubation and thus noticeable results which commonly have a unique plateau regions were obtained. However, any marked differences between added purines were not observed.4. Fluctuation of purine pools in cell was followed, using cation exchange resin, Dowex-50×4 in the presence of various purines. Thus, guanine was found to be accumulative but adenine was not detected in cell. Moreover, xanthine did not convert to any other purines and guanine also was not convertible except for its conversion to xanthine.5. Dynamic changes of purines in the 24 hr incubation medium were followed by the use of cation exchanger. However, the accumulation of particular purine derivatives was not observed.6. Only the third nucleotide fraction in the water eluting fraction of the column chromatography by cation exchanger characteristically fluctuated with the incubation. This fraction was found to consist of adenosine monophosphate and guanosine monophosphate. The changes of these nucleotides seem to be closely related to flavinogenesis.7. Xanthine contents inside and outside the cells at 24 hr of incubation were determined by using Florisil column and Dowex-50 column. Thus, guanine appeared to be converted to xanthine at the later stages of the incubation. Other purines were also well in accordance with the results of Summary 2.

Xanthine

Hypoxanthine

Purine metabolism

10.5925/jnsv1954.18.137

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Citations (6)

Uric acid as electron acceptor of liver xanthine dehydrogenase

Journal of Molecular Catalysis (1979)

Enric I. Canela J Bozal

Hypoxanthine

Xanthine

Xanthine dehydrogenase