Xanthine

About: Xanthine is a research topic. Over the lifetime, 4046 publications have been published within this topic receiving 129820 citations. The topic is also known as: Xanthine.

New Pyrrolo[2,1-f]purine-2,4-dione and Imidazo[2,1-f]purine-2,4-dione Derivatives as Potent and Selective Human A3 Adenosine Receptor Antagonists

Abstract: Compounds presenting an additional fused ring on the xanthine nucleus have been reported to exhibit antagonistic activity with various levels of affinity and selectivity toward the four adenosine receptors subtypes A1, A2A, A2B, and A3. This paper reports synthesis and biological evaluation of new 1-benzyl-3-propyl-1H,6H-pyrrolo[2,1-f]purine-2,4-diones and 1-benzyl-3-propyl-1H,8H-imidazo[2,1-f]purine-2,4-diones, among which we identified potent and selective A3 adenosine receptors antagonists. In particular, 1-benzyl-7-methyl-3-propyl-1H,8H-imidazo[2,1-f]purine-2,4-dione (11e) shows a Ki (hA3) value from binding assay of 0.8 nM.

The influence of electronic, steric and hydrophobic properties of flavonoid compounds in the inhibition of the xanthine oxidase

Abstract: Xanthine oxidase (XO) is an enzyme with the capacity of catalyzing the changing of hypoxanthine in xanthine. Afterwards, the xanthine is transformed in urate which in high levels is responsible for several diseases such as gout, renal diseases and stone formation in the urinary system. Allopurinol is a powerful inhibitor of the XO enzyme and it is used as a medication in cases where it is necessary to inhibit the XO enzyme action. In the literature, several flavonoid compounds have been described as inhibitors of the XO enzyme in a similar way that presented by allopurinol. In this work, a study on the influence of electronic, steric and hydrophobic properties of some flavonoid compounds in inhibiting the XO activity was carried out by using molecular mechanics (MM+) and semi-empirical (AM1) methods. From the results obtained, we were able to correlate the molecular properties of the flavonoid compounds studied with the inhibition of the XO.

Oxidants differentially regulate the heat shock response

Abstract: Cells, animals, and humans respond to hyperthermia through the synthesis of a family of proteins termed heat shock proteins (HSPs). Because hyperthermic stress may also result in mitochondrial uncoupling and the generation of reactive oxygen species, we wondered whether oxidant stress was sufficient to increase cellular levels of HSP70. HSP70 was detected in cells heated or treated with menadione but not in those treated with hydrogen perioxide or xanthine/xanthine oxidase. We speculate that oxidant stress from menadione exposure is qualitatively different from exposure from hydrogen peroxide or xanthine/xanthine oxidase.

Hepatic xanthine levels as viability predictor of livers procured from non-heart-beating donor pigs.

Abstract: BACKGROUND The aim of the present study was to evaluate hepatic content of adenine nucleotides and their degradation products in non-heart-beating donor (NHBD) pigs and its relationship with recipient survival. METHODS Thirty animals were transplanted with an allograft from NHBDs. After warm ischemia (WI) time (20, 30, or 40 min), cardiopulmonary bypass and normothermic recirculation (NR) were run for 30 min. Afterward, the animals were cooled to 15 degrees C and liver procurement was performed. RESULTS Survival rate was 100% in the 20WI, 70% in the 30WI, and 50% in the 40WI. Livers from non-surviving animals had higher levels of xanthine after NR than livers from surviving animals. Logistic regression analysis revealed that xanthine at the end of NR was the only variable able to predict survival with a calculated sensitivity of 80% and a specificity of 60%. Prolongation of warm ischemic period leaded to a greater xanthine accumulation as well as increased plasma alpha-glutathione S-transferase levels at reperfusion. Xanthine at NR and alpha-glutathione S-transferase at reperfusion significantly correlated, indicating that donor xanthine contributes to some extent to the severity of the lesion by ischemia-reperfusion. CONCLUSIONS It is suggested that xanthine content in the donor is able to predict survival after transplantation. Xanthine is significantly involved in the hepatic lesion elicited by warm ischemia and subsequent ischemia-reperfusion associated to liver transplantation from a NHBD.