ABSTRACT
α-Glycosidase is an essential target for the management of postprandial serum glucose in diabetic patients. Therefore, the interest has been growing in the screening of α-glycosidase inhibitor from natural resource. In the present study, the structure and α-glycosidase inhibitory activity of a polysaccharide (named as ACPP-1) from Aconitum coreanum were investigated. Based on the results from high performance gel permeation chromatography, GC-MS and 1D/2D nuclear magnetic resonance spectroscopy, ACPP-1 was a highly-linear polysaccharide with a molecular weight of 34.0â¯kD and containing over 90 % of glucose. It was composed of (1â4)-α-d-Glcp and α-Araf. ACPP-1 exhibited a dose-dependent inhibitory eï¬ ;ect against α-glycosidase activity in vitro and the IC50 value was â¼0.8â¯mg/mL. In oral starch tolerance test, treatment with ACPP-1 (800â¯mg/kg) significantly improved the starch tolerance in mice. Taken together, this study provided a potential intervention and management for postprandial hyperglycemia by the polysaccharide fraction from A. coreanum.
Subject(s)
Aconitum/chemistry , Glycoside Hydrolase Inhibitors/chemistry , Polysaccharides/chemistry , alpha-Glucosidases/chemistry , Animals , Chromatography, Gel , Glycoside Hydrolase Inhibitors/pharmacology , Humans , Mice , Molecular Weight , Plant Extracts/chemistry , Plant Extracts/pharmacology , Polysaccharides/pharmacology , Polysaccharides/ultrastructure , alpha-Glucosidases/pharmacology , alpha-Glucosidases/ultrastructureABSTRACT
Elongation factor Tu (EF-Tu) is involved in the binding and transport of the appropriate codon-specified aminoacyl-tRNA to the aminoacyl site of the ribosome. We report herewith that the Escherichia coli EF-Tu interacts with unfolded and denatured proteins as do molecular chaperones that are involved in protein folding and protein renaturation after stress. EF-Tu promotes the functional folding of citrate synthase and alpha-glucosidase after urea denaturation. It prevents the aggregation of citrate synthase under heat shock conditions, and it forms stable complexes with several unfolded proteins such as reduced carboxymethyl alpha-lactalbumin and unfolded bovine pancreatic trypsin inhibitor. The EF-Tu.GDP complex is much more active than EF-Tu.GTP in stimulating protein renaturation. These chaperone-like functions of EF-Tu occur at concentrations that are at least 20-fold lower than the cellular concentration of this factor. These results suggest that EF-Tu, in addition to its function in translation elongation, might be implicated in protein folding and protection from stress.
