The oxidation of guanine to an N-oxide and its hydrolysis to a xanthine N-oxide are rejorted. The s.c. administration of the xanthine N-oxide to rats for 6 months resulted in development of a variety of tumors. There were 1 liposarcoma, 3 fibrosarcomas, 1 nmmmary adenocarcinoma, 3 fibrohlastic tumors, 2 rhabdomyosarcomas, and 1 epideiinoid carcinoma at the site of injection and elsewhere in 11 ...

Some novel as well as known derivatives of 8-sulfanyl-3,9dihydro-1H-purine-2,6-dione were synthesized and their antithyroid activity was measured in rats after administration of a daily dose of 20mg/kg via i.p. injection for 15 days. Free thyroxine and triiodothyronine concentrations were determined using radioimmunoassay technique. The assay results showed decrease in the hormonal concentratio...

The vasodilator potency of the adenine nucleotides has been quantitated. Adenosine and AMP were found to be of equal potency and approximately one fourth as effective as ADP and ATP in increasing coronary blood flow. With the exception of UTP, which was also one fourth as potent as ATP, the derivatives of the hypoxanthine, guanine, cytosine and unveil bases lacked vasodilator properties. An inc...

Acetoxy esters of purine W-oxides inactivate and induce mutations in Bacillus jwà ̈n/Ã1-transforming DNA. The es ters were the chemical models available for the sulfate es ters believed to be formed in vivo. When metabolic suscep tibilities were taken into consideration, there is a reasonable correlation between the mutagenicity of various acetoxy es ters and the oncogenicity of the parent W-oxi...