Stereocontrolled Total Synthesis of 1a,25-Dihydroxyergocalciferol

A stereocontrolled total synthesis of the vitamin D2metabolite 1a,25-dihydroxyergocalciferol (1), which involves a coupling of the previously described A ring synthon 2 with the appropriately functionalized C-D moiety 3, is described. In the key step, stereochemical control is achieved by taking advantage of the thermal reversibility of a [3+ 2]-cyc1oaddition of methyl 0,~-dimethylacrylate and the C-D C-23 nitrone 4 to effect conversion to the C-24S isoxazolidinecarboxylic acid methyl ester Sa, which is readily transformed by reduction followed by elimination of the nitrone function into the necessary C-D precursor

Hepatoprotective effects of Gentiana asclepiadea L. extracts against carbon tetrachloride induced liver injury in rats

This study is an attempt to evaluate the hepatoprotective activity of Gentiana asclepiadea L against carbon tetrachloride-induced liver injury in rats. Methanol extracts of aerial parts (GM) and roots (GAR) of G. asclepiadea at doses of 100, 200, and 400 mg/kg b.w. were orally administered to Wistar rats once daily for 7 days before they were treated with CCl4. The hepatoprotective activity of the extracts in this study was compared with the reference drug silymarin. In CCl4 treated animals, GM and GAR significantly decreased levels of serum transaminases, alkaline phosphatase and total bilirubin, and increased the level of total protein. Treatment with the extracts resulted in a significant increase in the levels of catalase, superoxide dismutase and reduced glutathione, accompanied with a marked reduction in the levels of malondialdehyde, as compared to CCl4 treated group. The histopathological studies confirmed protective effects of extracts against CCl4-induced liver injuries. No genotoxicity was observed in liver cells after GM treatment, while GAR showed only slight genotoxic effects by comet assay. Phytochemical analysis revealed the presence of sweroside, swertiamarin and gentiopicrin in high concentrations in both extracts. It could be concluded that the use of G. asclepiadea extracts in the treatment of chemical-induced hepatotoxicity. (C) 2012 Elsevier Ltd. All rights reserved.Ministry of Education and Science of the Republic of Serbia [III 43004