Xanthine oxidase synthesis

Allomaltol, methyl — see Pyran-4-one, 5-methoxy-2-methyl-Allopurinol applications, 5, 343 metabolism, 1, 237 synthesis, 5, 316, 340 tautomerism, 5, 308 xanthine oxidase inhibition by, 1, 173 Allopurinol, oxy-applications, 5, 343 synthesis, 5, 316 Alloxan... 

Boroxazothienopyridines, 4, 1029-1032 Borsche synthesis, 3, 44 Botrydiplodin mass spectrometry, 4, 585 Boulton-Katritzky rearrangement, 5, 288 Bovine milk xanthine oxidase substrates, 1, 234 Bradsher reaction... 

Xanthine anions structure, 5, 509 Xanthine-8-carboxylic acid synthesis, 3, 308, 322 Xanthine oxidase... 

AHopurinol inhibits xanthine oxidase and also can reduce purine synthesis by inhibiting PRPP amidotransferase (provided HPRT is active). Hyperuricemia and gout often accompany the following conditions ... 

X-ray crystallography, 40 20-21 synthetic models, 40 23-48 xanthane oxidase, 40 21-23 chalcogenide halides, 23 370-377, 413 Chevrel phases, 23 376-377 metal-metal bonding, 23 330, 373 structural data, 23 373-376 as superconductors, 23 376 synthesis, 23 371-372 chloride, 46 4-24, 35-44 heterocations of, 9 290, 291 cluster compounds, 44 45-46 octahedral, 44 47-49, 53-63 electronic structure, 44 55-63 molecular structure, 44 53-54 synthesis, 44 47-49 rhomboidal, 44 75-82 solid-state clusters and, 44 66-72, 74-75, 80-82, 85-87 tetrahedral, 44 72-75 triangular, 44 82-87 cofactor, 40 2, 4-12 anaerobic isolation, 40 5 molybdopterin and, 40 4-8 reduced form, 40 12 synthesis, 40 8-12 xanthine oxidase, 45 60-63 complexes... 

Allopurinol, in contrast to the uricosuric drugs, reduces serum urate levels through a competitive inhibition of uric acid synthesis rather than by impairing renal urate reabsorption. This action is accomplished by inhibiting xanthine oxidase, the enzyme involved in the metabolism of hypoxanthine and xanthine to uric acid. After enzyme inhibition, the urinary and blood concentrations of uric acid are greatly reduced and there is a simultaneous increase in the excretion of the more soluble uric acid precursors, xanthine and hypoxanthine. 

Nagamatsu and co-workers also reported the reaction of 30 with hydrazine to produce 31, a key intermediate in the synthesis of potential xanthine oxidase inhibitors 32 <99CC1461>. The regioselectivity of this hydrazine displacement thus paralleled that observed with carbanionic nucleophiles. 

As indicated in Fig. 25-18, free adenine released from catabolism of nucleic acids can be deaminated hydrolytically to hypoxanthine, and guanine can be deaminated to xanthine.328 The molybdenum-containing xanthine oxidase (Chapter 16) oxidizes hypoxanthine to xanthine and the latter on to uric acid. Some Clostridia convert purine or hypoxanthine to xanthine by the action of a selenium-containing purine hydroxylase.3283 Another reaction of xanthine occurring in some plants is conversion to the trimethylated derivative caffeine. 328b One of the physiological effects of caffeine in animals is inhibition of pyrimidine synthesis.329 However, the effect most sought by coffee drinkers may be an increase in blood pressure caused by occupancy of adenosine receptors by caffeine.330... 

On the other hand, drugs may inhibit the metabolism of other drugs. For example, allopurinol (a xanthine oxidase inhibitor that inhibits the synthesis of uric acid) increases the effectiveness of anticoagulants by inhibiting their metabolism. Chloramphenicol (a potent inhibitor of microsomal protein synthesis) and cimetidine (an H2-receptor blocker used in acid-pepsin disease) have similar properties. In addition, drugs may compete with each other in metabolic reactions. In methyl alcohol (methanol) poisoning, ethyl alcohol may be given intravenously to avert methanol-induced blindness and minimize the severe acidosis. Ethyl alcohol competes with methyl alcohol for... 

Allopurinol (Zyloprim) reduces the synthesis of uric acid by inhibiting the activity of xanthine oxidase, according to the scheme shown in Figure 24.2. The reduction in the uric acid pool occurs slowly. Because xanthine and hypoxanthine are more soluble than uric acid, they are easily excreted. 

An alternative to increasing uric acid excretion in the treatment of gout is to reduce its synthesis by inhibiting xanthine oxidase with allopurinol. 

Xanthine oxidase is able to bind allopurinol and catalyze one oxidation, converting it to a compound that is similar to xanthine. However, after that conversion, the enzyme is trapped in an inactive oxidation state and can t carry out its normal function of forming uric acid. Additionally, allopurinol inhibits the de novo ( new, from other compounds not recycled) synthesis of purines, further decreasing the amount of uric acid formed in the blood. 

Phenyl-l,2,3-triazolo[4,5-d]pyrimidin-7(6//)-one has bactericidal activity against Bacillus subtilis and Staphylococcus aureus (94MI2). 1-Benzyl-4-ethoxycarbonylpiperazinyl-l//-l,2,3-triazolo[4,5-d]pyrimidine almost completely removed cytokinin-stimulated effects in betacyanin synthesis in Amaranthus caudatus cotyledons, growth of radish cotyledons, and retention of chlorophyll in leaf explants (94MI4). Analogs of 117 were used as effective inhibitors of xanthine oxidase (95FA257). 

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