The crystal structure of tetrakis(cytosine)copper(rI) perchlorate dihydrate has been determined. All the hydrogen atoms were obtained from Fourier-difference synthesis. The geometry around copper is a bicapped octahedron (4 + 2 + 2*). The adjacent cytosine rings are oriented head-to-tail with respect to each other and are roughly at right angles to the co-ordination plane. The exocyclic 0x0 groups form an interligand, intracomplex hydrogen-bonding network above and below the co-ordination plane with the exocyclic amino groups of alternate cytosine bases. The EPR and electronic spectra are consistent with the retention of the solid-state structure in solution. The steric effect of the C(2)=0 group of cytosine is offset by the presence of the intracomplex hydrogen-bonding network. The trend in El values of Cu"-Cu' couples for 1 : 4 complexes of cytosine, cytodine, pyridine, 2-methylpyridine and N-methylimidazole suggests that both steric effects and n-delocalization in imidazole and pyridine ligands and the steric effect of C(2)=0 in pyrimidine ligands are important in stabilising Cu' relative to Cu".

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D-Galactosamine (GalN)-induced liver injury is associated with reactive oxygen species and oxidative stress. In the present study, we evaluated the effect of alpha lipoic acid (ALA) supplementation on acute GalN-induced oxidative liver injury. Hepatotoxicity induced by single intraperitoneal injection of GalN (500 mg/kg body wt) was evident from increase in lipid peroxidation and serum marker enzymes (asparate transaminase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase). The decreased activities of enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) as well as glutathione levels were the salient features observed in GalN-induced hepatotoxicity. Pretreatment with ALA (50 mg/kg body weight for 7 days) significantly precluded these changes and prevents the hepatic injury. Hence, this study clearly exemplified that ALA might be a suitable candidate against GalN-induced cellular abnormalities.

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Azathioprine (AZA), one of the widely prescribed immunosuppressant drugs in organ transplantation and autoimmune diseases, could cause hepatotoxicity in the course of therapy. The current work was designed to assess the protective role of the dietary flavonoid, quercetin (QE), in oxidative hepatic damage induced by AZA. Adult male Wistar rats were divided into four treatment groups. Two groups were treated with single intraperitoneal injection of AZA (50 mg/kg body weight); one of these groups was pretreated with QE (50 mg/kg body weight) intraperitoneally once a day for 7 days. A vehicle treated control group and a QE control group were also included. Hepatotoxicity, evident from increased levels of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma glutamyl transpeptidase (GGT) in serum 24 h after AZA treatment, was significantly (p < 0.05) normalized by QE pretreatment. AZA administered rats displayed declined levels of endogenous antioxidants [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione (GSH)], along with elevated levels of malondialdehyde (MDA). However, pretreatment with QE significantly precluded lipid peroxidation and maintained the activities of antioxidant defenses at a near normal status. Besides, AZA induced oxidative stress and subsequent DNA damage was effectively manifested by QE, which was confirmed by agarose gel electrophoresis. These findings highlight the salubrious effect of QE as a hepatoprotectant in AZA-induced oxidative stress mediated hepatic injury.

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