Hypoxanthine-3-N-oxide

Pfeiffer, W., Riegelbauer, G., Meier, G., and Scheibler, B., 1985, Effect of hypoxanthine-3-N-oxide and hypoxanthine-l-Af-oxide on central nervous excitation of the black tetra, Gymnocorymbus temetzi (Characidae, Ostariophysi, Pisces) indicated by dorsal light response, J. Chem. Ecol. 11 507-523. 

Trap experiments have also been used to determine the chemical composition of Ostariophysan alarm cues. In a study by Brown et al. (2000), traps labeled with fathead minnow extract, hypoxanthine-3-N-oxide or pyridine-N-oxide caught significantly fewer fishes (including dace and minnow) than those labeled with distilled water. These field results validate the outcome of laboratory studies in which significant increases in antipredator behavior in both fathead minnows and finescale dace were observed when they... 

Hypoxanthine is oxidized at carbon 2 by both molybdenum hydroxylases, although xanthine oxidase is much more effective as a catalyst in this reaction [ 10]. A methyl substituent in this position prevents oxidation by either enzyme. Introduction of A-methyl substituents into the hypoxanthine nucleus produces dramatic effects on enzymic oxidation rates and also gives some insight into the productive modes of binding to each enzyme. Thus, it has been proposed that hypoxanthine tautomerizes in the xanthine oxidase-substrate complex to the 3-NH-form with a simultaneous shift of the NH-group in the imidazole ring from position 9 to 7 [ 198,200]. In support of this hypothesis, when tautomerism in the imidazole ring is prevented by substitution at N-7 or N-9, such compounds are almost refractory to oxidation (see Table 3.9)... 

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