Gundelia tournefortii Antidiabetic Efficacy: Chemical Composition and GLUT4 Translocation.

In the present in vitro study, we tested the chemical composition, cytotoxicity and antidiabetic activity of two distinct extracts of wild Artichoke-like vegetable, Gundelia tournefortii: methanol and hexane. GC/MS phytochemical analysis of G. tournefortii methanol and hexane extracts revealed 39 compounds reported here for the first time in G. tournefortii out of the 45 detected compounds. Only Stigmasterol was present in both extracts. The efficacy of G. tournefortii extracts in enhancing glucose transporter 4 (GLUT4) translocation to the plasma membrane (PM) was tested in L6 muscle cells stably expressing myc-tagged GLUT4 (L6-GLUT4myc) using cell-ELISA test. Results obtained here indicate that methanol and hexane extracts were safe up to 250 µg/ml as measured with MTT and the LDH leakage assays. The methanol extract was the most efficient in GLUT4 translocation enhancement. It increased GLUT4 translocation at 63 µg/ml 1.5- and 2-fold relative to the control in the absence and presence of insulin, respectively. These findings indicate that G. tournefortii possesses antidiabetic activity in part by enhancing GLUT4 translocation to the PM in skeletal muscle.

In vitro evaluation of anti-diabetic activity and cytotoxicity of chemically analysed Ocimum basilicum extracts.

The aim of this study was to evaluate the role of glucose transporter-4 (GLUT4) in the anti-diabetic effects of methanol, hexane and dichloromethane extracts of the aerial parts of Ocimum basilicum (OB) and to analyze their phytochemical composition. Phytochemical analysis of the three extracts by GC/MS using the silylation derivatization technique revealed 53 compounds, 17 of them were found for the first time in OB. Cytotoxic and anti-diabetic properties of the extracts were evaluated using L6-GLUT4myc muscle cells stably expressing myc epitope at the exofacial loop (GLUT4). No cytotoxic effects were observed in treated cells up to 0.25 mg/ml extract as measured with MTT and LDH-leakage assays. GLUT4 translocation to the plasma membrane was elevated by 3.5 and 7 folds (-/+ insulin) after treatment with OB extracts for 20 h. Our findings suggest that the observed anti-diabetic properties of OB extracts are possibly mediated in part through one or more of the 17 new identified compound.

In Vitro Evaluations of Cytotoxicity of Eight Antidiabetic Medicinal Plants and Their Effect on GLUT4 Translocation.

Despite the enormous achievements in conventional medicine, herbal-based medicines are still a common practice for the treatment of diabetes. Trigonella foenum-graecum, Atriplex halimus, Olea europaea, Urtica dioica, Allium sativum, Allium cepa, Nigella sativa, and Cinnamomum cassia are strongly recommended in the Greco-Arab and Islamic medicine for the treatment and prevention of diabetes. Cytotoxicity (MTT and LDH assays) of the plant extracts was assessed using cells from the liver hepatocellular carcinoma cell line (HepG2) and cells from the rat L6 muscle cell line. The effects of the plant extracts (50% ethanol in water) on glucose transporter-4 (GLUT4) translocation to the plasma membrane was tested in an ELISA test on L6-GLUT4myc cells. Results obtained indicate that Cinnamomon cassia is cytotoxic at concentrations higher than 100 µ g/mL, whereas all other tested extracts exhibited cytotoxic effects at concentrations higher than 500 µ g/mL. Exposing L6-GLUT4myc muscle cell to extracts from Trigonella foenum-graecum, Urtica dioica, Atriplex halimus, and Cinnamomum verum led to a significant gain in GLUT4 on their plasma membranes at noncytotoxic concentrations as measured with MTT assay and the LDH leakage assay. These findings indicate that the observed anti-diabetic properties of these plants are mediated, at least partially, through regulating GLUT4 translocation.