• Archives of Pharmacal Research
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• v.10 no.1
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• pp.36-41
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• 1987

The conversion of xanthine dehydrogenase (type D) into xanthine oxidase (type D) was significantly increased in serum and liver of all $CCI_4$ treated rats on the necrosis and early cirrhosis stage of liver tissue. In the pretreatment of prednisolone, the ratio of type O per type O + D showed the decreasing tendency in serum, but the significant decrease in liver. In vitro, the conversion of liver xanthine oxidase from type D into type O was markedly increased by following preincubation with lysosomal fraction. The type conversion of xanthine oxidase may be caused by protelytic enzymes in lysosome.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.610-613
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• 1991

Some of the Kinetic properties of crystallic xanthine dehydrogenase form Pseudomonas synxantha A3 were studied. The enzyme activity was strongly inhibited by adenine, 8-azaadenine, 2-methyladenine, guanine, and 8-azaguanine, but not by caffeine, and the inhibitions by adenine and guanine were observed to be of noncompetitive type. The $K_i$ values for adenine and guanine were 0.037 and 0.098 mM, respectively. Michaelis constants were found to be 0.33 and 0.06 rnM for hypoxanthine and xanthine with $NAD^+$ as the second substrate, respectively, and 0.1 rnM for $NAD^+$ with either hypoxanthine or xanthine as the second substrate.

• YAKHAK HOEJI
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• v.39 no.5
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• pp.521-527
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• 1995

This study was done to determine the effect of lead acetate on the activities of the hepatic cytosofic xanthine oxidase and aldehyde oxidase which were well known as oxygen free radical generating enzyme in vitro. Lead ion accelerated the formation of lipid peroxide and the increment of xanthine oxidase(type O) activity and the type conversion ratio from xanthine dehydrogenase to xanthine oxidase dose-dependently. But xanthine dehydrogenase(type D) activity was decreased. Aldehyde oxidase activity was not changed by lead ion. These data suggested that lead-induced cellular to)dcity may be concerned partially with xanthine oxidase mediated lipid peroxidation.

• Advances in Traditional Medicine
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• v.7 no.5
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• pp.477-484
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• 2008

The present study was aimed at investigating the hypouricemic and xanthine oxidase inhibitory activities of the various fractions of the hydromethanolic extract of the leaves of Coccinia grandis L. Voigt (Cucurbitaceae). The leaves of this species was used in traditional medicinal system for the treatment of gout, rheumatism, jaundice, bronchitis, fever, skin eruptions, wounds, etc. The degree of xanthine oxidase inhibition was determined in vitro by measuring the increase in absorbance at 295 nm associated with uric acid formation. Among the fractions tested, the chloroform fraction exhibited highest potency ($IC_{50}$ $17.8\;{\mu}g/ml$). This was followed by the pet-ether ($IC_{50}$ $29.7\;{\mu}g/ml$), ethyl acetate ($IC_{50}$ $41.2\;{\mu}g/ml$) and residual ($IC_{50}$ $47\;{\mu}g/ml$) fractions. The $IC_{50}$ value of allopurinol was $6.1\;{\mu}g/ml$. In addition, the hypouricemic and hepatic xanthine oxidase (XO)/xanthine dehydrogenase (XDH) inhibitory activities of the fractions were examined in vivo using oxonate (280 mg/kg, i.p.) induced hyperuricemic mice. At a dose of 200 mg/kg orally for 7 days, the pet-ether, chloroform and ethyl acetate fractions produced a significant (P < 0.01) reduction in serum urate level and also inhibited hepatic XO/XDH activities when compared to hyperuricemic mice. These inhibitory effects were weaker than that observed for the standard drug, allopurinol (10 mg/kg, p.o.). Lineweaver-Burk analysis of the enzyme kinetics indicated that the mode of inhibition was of a mixed type. These results suggest that the use of Coccinia grandis leaves for the treatment of gout could be attributed to its XO inhibitory activity.

• YAKHAK HOEJI
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• v.38 no.2
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• pp.211-217
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• 1994

Copper intoxication and disturbance of copper metabolism induced various oxygen-derived free radicals related damages. The effect of copper ion on xanthine oxidase activity and type conversion of the enzyme which is concerned to generation of reactive oxygen species, was investigated, It was observed that xanthine oxidase activity was increased by addition of copper ion in the reaction mixture in proportional to the concentration of the metal ion until $60\;{\mu}M$, while the enzyme activity was inhibited in higher concentration of copper treatment. On the other hand, xanthine dehydrogenase activity was inhibited by copper ion addition with concentration dependently. Preincubation of enzyme source with $30\;{\mu}M$ of copper ion, which concentration marked increased the xanthine oxidase activity, unchanged the enzyme activity and type conversion compare to control in vitro system. It was also observed that copper induced xanthine oxidase activity and the enzyme type conversion was protected by dithiothreitol and penicillamine. These results indicate that the increment of the type conversion of xanthine oxidase necessarilly need the presence of copper ion in enzyme assay system.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.356-360
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• 2005

Xanthine dehydrogenase (XDH), a classic enzyme involved in purine catabolism, can catalyze the formation of redox-signaling reactive oxygen and nitrogen species such as superoxide and nitric oxide. We generated transgenic plants of Arabidopsis in which XDH was knocked out by introduction of hairpin RNA-expression vector. Expression analysis by reverse transcription-PCR and in-gel staining of XDH activity revealed that transgenic lines efficiently suppressedXDH expression at the transcriptional level, demonstrating that RNA interference was successfully induced. XDH-suppressed transgenic lines exhibitedincreased biomass production during the growth of seedlings.

• YAKHAK HOEJI
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• v.37 no.6
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• pp.647-658
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• 1993

The susceptibilities of aldehyde dehydrogenase (AldDH) and alcohol dehydrogenase (ADH) to active oxygen generated by xanthine-xanthine oxidase (XOD) system were studied. Incubation of AldDH with 2$\times$10$^{-3}$ units of XOD for 30 min at $25^{\circ}C$ resulted in the decrease of enzyme activity to 30% and it was inactivated completely when incubated with 5$\times$10$^{-3}$ units of XOD. Whereas 70% of ADH activity was retained after exposure to 5$\times$10$^{-3}$ units of XOD for 30 min, 40% of ADH activity was retained after exposure to 5$\times$10$^{-2}$ unit of XOD for 30 min. This inhibition effect by the active oxygen was preventable by catalase and glutathione, but not by SOD. The rates of the NADPH-dependent oxygen consumption by the liver S-9 mixture and microsomes were also determined in this study. Rate of oxygen consumption is increased in the liver S-9 mix and microsomes from phenobarbital-treated rat, and it was consistent with increased lipid peroxidation. In the presense of ethanol as a substrate, the oxygen consumption rates were increased. It is reported that hepatic AldDH activity is depressed in alcoholic liver diseases, however there is few report that explains the reason of depressed AldDH activity. These results are supportive of the theory that the increase in hepatic ethanol oxidation through the induced ME activity after chronic ethanol feeding generate oxygen radical at elevated rates and it leads to the depression of AldDH activity.

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.240.3-241
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• 2000

No Abstract, See Full Text

• Proceedings of the Korean Society of Life Science Conference
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• 2002.03a
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• pp.62-62
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• 2002

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.739-744
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• 1998

To evaluate an effect of ethanol pretreatment on the liver xanthine oxidase(XO) activity, 0.25ml of xylene(50% in olive oil) per 100g body weight was daily given four days to the rats at 2hrs after aministration of ethanol each day, while each control group(ethanol, xylene, olive oli) was treated as the same dose described as above. The animals were sacrificed at 24hrs after last injection. Xylene-treated rats showed the more decreased activity of liver XO compared to the control. But the pretreatment of ethanol to the xylene-treated rats enhanced the liver XO activity. Furthermore, the xylene-treated rats led to more increased Vmax value in liver XO compared to the only xylene-treated rats. On the other hadn, hepatic aldehyde dehydrogenase activity was more decreased in xylene-treated rats pretreated with ethanol than in xylene-treated rats. And the intermediated xylene metabolites, methyl benzylalcohol or aldehyde inhibited the XO activity "in vitro". In conclusion, the phenomenon that pretreatment of ethanol to the xylene-treated rats led to the enhancement of liver XO activity, may be due to an influence of acetaldehyde.taldehyde.