ABSTRACT
During the last few years, numerous attempts were made to identify effective α-glucosidase inhibitors from natural sources in order to develop new alternatives for diabetes management. Smallanthus sonchifolius (yacon) leaves were found to be effective in controlling postprandial hyperglycemia. Enhydrin, a constituent of yacon leaves, was noted for its significant hypoglycemic properties in diabetic rats. These properties were also demonstrated for yacon leaves decoction, which is rich in phenolic compounds such as chlorogenic acid and its derivatives. The purpose of the present study was to evaluate the potential of yacon leaves decoction and the isolated compound enhydrin to inhibit α-glucosidase enzyme, a possible mechanism of the above antihyperglycemic effect. In vitro assays showed that both 10% decoction and enhydrin significantly inhibited the activity of the yeast α-glucosidase enzyme in a dose-dependent manner, IC50 values being 50.40 and 134.17 µg/ml, respectively. In vivo experiments showed a rapid decrease in the hyperglycemic peak after sucrose load (2 g/kg body weight) in normal rats treated with the 10% decoction (140 mg/kg) and enhydrin (0.8 mg/kg). Both treatments caused a significant decrease in blood glucose levels in diabetic rats after sucrose load compared to diabetic control. These results suggest that both products assayed could be effective in the management of postprandial hyperglycemia through inhibition of α-glucosidase in the small intestine.
Subject(s)
Asteraceae/chemistry , Diabetes Mellitus, Experimental/drug therapy , Glycoside Hydrolase Inhibitors/pharmacology , Hyperglycemia/prevention & control , Hypoglycemic Agents/pharmacology , Sesquiterpenes/pharmacology , Animals , Chlorogenic Acid/isolation & purification , Chlorogenic Acid/pharmacology , Diabetes Mellitus, Experimental/chemically induced , Disease Models, Animal , Male , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Plant Leaves/chemistry , Rats , Rats, Wistar , Sesquiterpenes/chemistry , Sesquiterpenes/isolation & purification , Streptozocin/adverse effects , alpha-Glucosidases/metabolismABSTRACT
Vitronectin (vn) is a cell-adhesive glycoprotein present in blood and extracellular matrix of all vertebrates. In the present study we reported the cDNA cloning of Xenopus laevisvitronectin and its spatial and temporal expression pattern during the embryonic development of this important model organism. The deduced amino acid sequence of Xenopus laevis vn showed 49%, 47% and 43% identity with human, chicken and zebrafish orthologs, respectively, whereas the comparison with Xenopus tropicalis vn presented 85% identity. The structural organization consisting of a somatomedin B domain and two hemopexin-like domains was similar to higher vertebrate vitronectins. The vn transcripts were detected from stage 28 onward. At tadpole stages, vn is expressed in heart, gut derivatives and in the notochord. The protein was detected in heart, liver, foregut, pronephros and notochord at stages 43 and 47 of Xenopus embryos. Our results suggest that vitronectin is developmentally regulated and could participate in embryo organogenesis.
Subject(s)
Vitronectin/metabolism , Xenopus laevis/metabolism , Amino Acid Sequence , Animals , DNA, Complementary , Electrophoresis, Polyacrylamide Gel , Embryonic Development , In Situ Hybridization , Microscopy, Fluorescence , Molecular Sequence Data , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Amino Acid , Vitronectin/chemistry , Xenopus laevis/embryologyABSTRACT
Diabetes mellitus is characterized by anatomical and functional alterations of the intestinal tract. However, the aetiology of these disturbances remains unclear. The aim of the present work was to investigate the effects of diabetes on the expression of laminin-1 and fibronectin in the small intestine of Streptozotocin (STZ)-induced diabetic rats. The Western immunoblotting of the extracts from the small intestine revealed that experimental diabetes resulted in a marked increase in the intensity of the bands corresponding to laminin-1 and fibronectin. Immunohistochemical studies demonstrated a strong labelling to these two extracellular matrix (ECM) proteins in the small intestine of diabetic rats, mainly localized in the smooth muscle layer. These results occur together with a thickening of the basement membrane (BM) of the smooth muscle cells, demonstrated by transmission electron microscopy (TEM). We propose that the accumulation of ECM proteins in the smooth muscle layer may be an effect mediated by hyperglycaemia, since insulin treatment of diabetic rats reversed this accumulation. These results could provide information on the potential role of the ECM in the intestine, an organ which is known to exhibit important alterations in diabetes.
