Topic
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.
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TL;DR: Propofol had a direct scavenging activity against HOCl, superoxide-hydrogen peroxide and hydroxyl radical in the concentrations used, which may contribute to the effect of propofol on human leucocyte chemiluminescence.
Abstract: We have studied the ability of propofol and Intralipid to inhibit reactive oxygen species generated either by stimulated human leucocytes or cell-free systems using luminol chemiluminescence. Human leucocytes were stimulated by a chemotactic peptide, FMLP 1 mumol litre-1, or by a phorbol ester, PMA (protein kinase C activator) 0.1 mumol litre-1. In cell-free experiments, superoxide-hydrogen peroxide, hypochlorous acid or hydroxyl radical-induced chemiluminescence responses were initiated by xanthine 0.1 mmol litre-1 with xanthine oxidase 10 mu. ml-1, NaOCl 70 mumol litre-1 and FeSO4 3 mumol litre-1, respectively. Propofol with Intralipid, and to a lesser degree Intralipid alone, produced a concentration-dependent reduction in chemiluminescence from stimulated leucocytes. Similar attenuations were also observed using propofol with Intralipid on xanthine with xanthine oxidase-, HOCl- and ferrous iron-induced chemiluminescence. However, Intralipid produced a reduction only at high concentrations. Intralipid produced marked decreases in ferrous iron-induced chemiluminescence. This study suggests that propofol had a direct scavenging activity against HOCl, superoxide-hydrogen peroxide and hydroxyl radical in the concentrations used. These direct scavenging effects may contribute to the effect of propofol on human leucocyte chemiluminescence.
54 citations
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TL;DR: The potency and selectivity of 1,3-Dipropyl-8-phenylxanthine suggest that this approach can yield a versatile class of "functionalized congeners" of adenosine receptor antagonists in which distal modifications of the attached moiety can serve also to improve pharmacodynamic and pharmacokinetic parameters.
Abstract: 1,3-Dipropyl-8-phenylxanthine, a synthetic analog of theophylline and a potent antagonist of adenosine at A1 and A2-adenosine receptors, has been attached covalently through a functionalized chain to amino acids and oligopeptides. The xanthine conjugates have been studied as competitive inhibitors of the specific binding of [3H]N6-cyclohexyladenosine to A1-receptors of rat cerebral cortical membranes and for inhibition of cyclic AMP accumulation elicited by 2-chloroadenosine in guinea pig brain slices through A2-receptors. A free amino group on the extended chain generally resulted in high potency at A1-receptors. The potency (in some cases extending into the subnanomolar range) and selectivity for A1-receptors (up to 200-fold) suggest that this approach can yield a versatile class of "functionalized congeners" of adenosine receptor antagonists in which distal modifications of the attached moiety ("carrier") can serve also to improve pharmacodynamic and pharmacokinetic parameters. The water solubility in many of the more potent analogs has been enhanced by two orders of magnitude over that of simple, uncharged 8-phenyl xanthine derivatives. Analogs in which the carrier contains D-tyrosine have potential for development of iodinated radioligands for adenosine receptors. The functionalized congener approach is potentially applicable to other drugs and for development of prodrugs.
54 citations
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TL;DR: Spectroscopic evidence showed that the complexation of caffeine and theophylline with DNA occurred via G-C and A-T and PO2 group with overall binding constants of K(caffeine–DNA) = 9.7 × 103 M−1 and K(theophyllines–DNA), and the affinity of ligand–DNA binding is in the order of theophyLLine > caffeine.
54 citations
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TL;DR: Analysis of circular dichroism demonstrated that chrysin induced the conformational change of XO with increases in α-helix and β-sheet and reductions in β-turn and random coil structures, and the interaction was predominately driven by hydrogen bonds and van der Waals forces.
54 citations
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TL;DR: An automated screening system for purine and pyrimidine metabolism disorders using high-performance liquid chromatography (HPLC) with column switching is described, which offers a useful method for the detection of orotic aciduria, dihydropyrimidine dehydrogenase deficiency, xanthinuria, adenine phosphoribosyltransferase deficiency and adenylosuccinase deficiency.
54 citations