ABSTRACT
Aim: To show that Gymnema sylvestre (Roxb.) Asclepiadaceae not only has antidiabetic propensities, but it most likely works by regeneration of pancreatic cells which is imperative in anti-obesity-diabetes therapeutic applications of medicinal plants. Study Design: The present study design investigated the effects of G. sylvestre leaves crude aqueous extracts (AEs), traditionally utilized in diabetes treatment, on the pancreatic β-cell MIN6 proliferation and insulin secretion and extrapancreatic dietary carbohydrate and lipid digestion Place and Duration of Study: Faculty of Pharmacy, The University of Jordan, 2008-2012. Results: Comparable to GLP-1 (500 nM) pancreatic proliferative capacity; G. sylvestre AE concentrations (0.01 and 0.1 mg/mL) induced MIN6 monolayers expansion by respective 130.3% and 127.4% (P<0.001 vs. spontaneous control). Like L-alanine (10 mM) insulinotropic efficacy and without exerting cytotoxicity, glucose-stimulated insulin secretion was potentiated by G. sylvestre AEs (5, 10 and 25 mg/mL) (711.0%, 843.0% and 906.5%, respectively, P<0.001 vs. basal control). The potent plants’ insulin secretory bioactivities were abolished in the depleted Ca2+ conditions (P<0.001). Similar to orlistat antilipolytic efficacy, pancreatic lipase IC50 value for G. sylvestre AEs was 106.3±7.2 μg/mL. Unlike acarbose (100 μg/mL) dual inhibition of α-amylase/α-glucosidase, G. sylvestre AE was inactive at used doses. Dissimilar to guar gum (50 mg/mL) diffusional hindrance in a simple dialysis model, G. sylvestre AEs (10, 25 and 50 mg/mL) proved inactive. This in vitro ineffectiveness was mirrored in respective in vivo oral carbohydrate tolerance tests in overnight fasting normoglycemic rats. Conclusion: This evaluation has revealed that G. sylvestre leaves AEs augmented β-cell expansion and potentiated glucose-evoked Ca2+-regulated insulin secretion; combined with impressive antilipolytic activity. These actions depend on the bioactive water soluble phytoprinciples intact absorption in vivo. Future directives may assess the potential of G. sylvestre as a new alternative for anti-obesity-diabetes pharmacotherapy and prevention.
ABSTRACT
Aim: This study aimed to screen the aqueous and hydro-alcoholic extracts of Achillea falcata L. (Asteraceae) grown in Jordan for their antioxidant, antibacterial, antiplatelet and anti-proliferative efficacy. Study Design: HPLC-MS evaluation of the aqueous and hydro-alcoholic extracts and in vitro investigations. Place and Duration of Study: Faculties of Pharmacy and Science, The University of Jordan and Centre of Misanalysis, National Institute for Biological Sciences, between August 2012 and June 2013. Methodology: Total phenols and flavonoids were determined colorimetrically. The radical scavenging activities were evaluated using 2,2′-azino-bis-3-ethylbenzthiazoline-6- sulphonic acid (ABTS) radical scavenging activity assay. Antimicrobial activities were determined by the disc-diffusion method, and the minimum inhibition concentration and the minimum bactericidal concentration tests. In vitro antiplatelet activity was tested on human whole blood using an electrical impedance method. Anti-proliferative activity was investigated using the MTT assay. High performance liquid chromatography-mass spectrometry (HPLC-MS) evaluation was performed. Results: Hydro-alcoholic extract had a bactericidal activity against Streptococcus pneumoniae, Bacillus cereus and Klebsiella pneumoniae rather than inhibitory effect. No significant activity was observed against gram negative bacteria and Candida albicans. In vitro antiplatelet activity was tested on human whole blood using an electrical impedance method. At concentrations (50, 100, and 200 μg/ml), hydro-alcoholic extract did not show effect on platelet aggregation. Extracts did not possess cytotoxic activity against the MCF- 7 cells at concentrations up to 200 μg/ml. HPLC-MS analysis resulted in the identification of 8 phenolic compounds in the hydro-alcoholic extract and 6 compounds in the aqueous extract; quercetin 3-β-D-glucoside was the main component for both extracts. Conclusion: The present investigation supported the traditional use A. falcata in the Jordanian folk medicine as a depurative agent and as an antimicrobial active representative of the genus Achillea.