Sunroot mediated synthesis and characterization of silver nanoparticles and evaluation of its antibacterial and rat splenocyte cytotoxic effects.

A rapid, green phytosynthesis of silver nanoparticles (AgNPs) using the aqueous extract of Helianthus tuberosus (sunroot tuber) was reported in this study. The morphology of the AgNPs was determined by transmission electron microscopy (TEM). Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD) analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy (FTIR) analysis revealed that biomolecules in the tuber extract were involved in the reduction and capping of AgNPs. The energy-dispersive spectroscopy (EDS) analysis of the AgNPs, using an energy range of 2-4 keV, confirmed the presence of elemental silver without any contamination. Further, the synthesized AgNPs were evaluated against phytopathogens such as Ralstonia solanacearum and Xanthomonas axonopodis. The AgNPs (1-4 mM) extensively reduced the growth rate of the phytopathogens. In addition, the cytotoxic effect of the synthesized AgNPs was analyzed using rat splenocytes. The cell viability was decreased according to the increasing concentration of AgNPs and 67% of cell death was observed at 100 µg/mL.

Isolation and structural characterization of 2R, 3R taxifolin 3-O-rhamnoside from ethyl acetate extract of Hydnocarpus alpina and its hypoglycemic effect by attenuating hepatic key enzymes of glucose metabolism in streptozotocin-induced diabetic rats.

Hydnocarpus alpina Wt. (Flacourtiaceae) (H. alpina) is a large tree traditionally used to treat leprosy; it also posses antidiabetic property. The present study was undertaken to isolate, characterize and to evaluate the antidiabetic effect of 2R, 3R taxifolin 3-O-rhamnoside. (rhamnoside) and its impact on carbohydrate metabolic key enzymes in control and streptozotocin (STZ)-induced diabetic rats. Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ) (40 mg/kg). Oral administration of rhamnoside for 21 days significantly reduced food intake, calorie intake, blood glucose and glycosylated hemoglobin levels, and improved plasma insulin levels. Administration of rhamnoside showed significant increase in the body weight, body composition (Lean body weight (LBW) and retro body fat), glycolytic hexokinase, glucose-6-phophate dehydrogenase and pyruvate kinase levels where as significant decrease was observed in the levels of glucose-6-phosphatase fructose-1, 6-bisphosphatase and lactate dehydrogenase in diabetic treated rats. Further, administration of rhamnoside significantly improved the glycogen content, glycogen synthase and glycogen phosphorylase, suggesting the antihyperglycemic potential of rhamnoside in diabetic rats. The results obtained were compared with glibenclamide a standard hypoglycaemic drug. Immunohistopathological study of pancreas revealed increased number of ß-cells and insulin granules in diabetes-induced rats after treatment with rhamnoside for 21 days. Furthermore, Co-administration of rhamnoside (50 mg/kg) with nifedipine (13.6 mg/kg), a Ca(2+)ion channel blocker, or nicorandil (6.8 mg/kg), an ATP-sensitive K(+) ion channel opener, reveals the insulin secretion property of rhamnoside via a K(+)-ATP channels dependent pathway in diabetic rats. In conclusion, rhamnoside normalized blood glucose, glycosylated hemoglobin, key hepatic enzymes and glycogen content by increasing insulin secretion via K(+)-ATP channels dependent signaling pathway. The results suggest that the rhamnoside from H. alpina could be used as a therapeutic agent to treat diabetes mellitus.

Molecular docking of γ-sitosterol with some targets related to diabetes.

γ-sitosterol isolated from Lippia nodiflora was taken as ligand for molecular docking. The molecular targets, glucokinase, Fructose 1, 6- bisphosphatase 1, Human multidrug resistance protein 1 and Cytochromes P450 whose crystallographic structures are available on the PDB database as 1V4S, 2JJK, 3LC4, 2CBZ respectively, were used for the docking analysis using the Autodock tool v 4.2 and ADT v1.5.4 programs. The docking studies of the ligand γ- sitosterol with four different target proteins showed that this is a good molecule which docks well with various targets related to diabetes mellitus. Hence γ-sitosterol can be considered for developing into a potent antidiabetic drug.

Antidiabetic activity of γ-sitosterol isolated from Lippia nodiflora L. in streptozotocin induced diabetic rats.

Lippia nodiflora L. (Verbenaceae) is a creeping perennial herb widely used in traditional system of medicine to treat ulcers, bronchitis and heart diseases; it also possesses antidiabetic property. In the present study, γ-sitosterol isolated from Lippia nodiflora was screened for its antidiabetic property in streptozotocin (STZ) induced diabetic rats. Insulin secretion in response to glucose was evaluated in isolated rat islets. Oral administration of γ-sitosterol (20 mg/kg body weight) once daily for 21 days in STZ-induced diabetic rats resulted in a significant decrease in blood glucose and glycosylated hemoglobin with a significant increase in plasma insulin level, body weight and food intake. Furthermore γ-sitosterol showed antihyperlipidemic activity as evidenced by significant decrease in serum total cholesterol, triglycerides and very low density lipoprotein-cholesterol levels coupled with elevation of high density lipoprotein-cholesterol levels in treated rats. A significant decrease in the activities of alanine aminotransaminase, aspartate aminotransaminase, alkaline phosphatase and acid phosphatase in γ-sitosterol treated rats when compared to diabetic control rats indicated its protective role against liver damage. γ-Sitosterol increased insulin secretion in response to glucose. Immunohistochemical study of pancreas also confirmed the biochemical findings. These results indicated that γ-sitosterol, the compound isolated from L. nodiflora, possessed antihyperglycemic activity.