An in-depth study of the L2 long-loop region of human chorionic gonadotrophin (hCG), earlier identified to be a conformational bioneutralization epitope and receptorbinding site of the hormone, was carried out. The linear 38-57 hCG peptide and the corresponding cyclic disulphide peptide were synthesized and antipeptide antibodies developed. Binding studies with antibodies to the linear peptide, and with hCG , hCG and human LH suggest that part of the region is buried at the / interface and part exposed in hCG. Observation of the surface exposure of residues 47-53 from the crystal structure of hCG was confirmed by epitope mapping studies of the region. The region is not unique to hCG as a majority of the antibodies to both the linear and cyclic peptides did not exhibit the required specificity. Competitive inhibition studies with the linear and cyclic peptides failed to show inhibition of radiolabelled hCG binding to its receptors. However, both the antipeptide antibodies were able to bioneutralize the hormone in an in vivo assay. Taken together, these results seem to indicate that the L2 long-loop region is not a receptor-binding site of hCG but spatially close to it.
The aqueous extract of bark of Careya arborea Roxb., locally known as Kumbhi, was screened for hepatoprotective activity against CCl 4 -induced hepatotoxicity in rats with a view to explore its application for treatment of liver disorders in animals and human beings. The hepatotoxicity induced by administration of carbon tetrachloride (CCl 4 ) as 30 % solution prepared in liquid paraffin and administered subcutaneously 1ml/kg b.wt. at every 72 h interval till the completion of experiment. The hepatotoxicity was found to be tolerated by simultaneous oral administration of aqueous extract of C. arborea (AECA) stem bark (100, 200 mg/kg b. wt.) for two weeks, with evidence of decreased level of AST, ALT, ALP and bilirubin. In addition, severe histomorphological disruption and fatty changes produced by CCl 4 in respect of cytoarchitecture were minimized and maintained by the treatment of extract. The results were compared with standard drug silymarine. The results of this study showed that AECA could afford hepatoprotective activity against CCl 4 induced liver damage in rats due to nutraceutical nature of plant.
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