Glucose uptake-stimulatory activity of Tinospora cordifolia stem extracts in Ehrlich ascites tumor cell model system

Abstract

Diabetes mellitus is a multifunctional disorder with several causes and multiple consequences. Nutraceuticals play a vital role in ameliorating diabetic condition. The stems of the plant, Tinospora cordifolia (T. cordifolia) are often used in Ayurvedic medicine for the management of diabetes. Earlier studies have shown that T. cordifolia to be a potent antidiabetic plant material by virtue of being rich in nutraceuticals. In the present study we were interested to know if, T. cordifolia stem extracts are able to promote glucose uptake through glucose transporters, 1 (GLUT1) and 3 (GLUT3), which are responsible for basal glucose uptake. Hence, Ehrlich ascites tumor (EAT) cells were chosen as a model which harbours both GLUT1 and GLUT3 and glucose uptake was measured using a fluorescent analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG). Serially, solvent extracted T. cordifolia stems, especially water, ethanol and methanol extracts showed glucose uptake activity. Uptake was stimulated in a dose dependent manner at dosages of 1-100 μg. Glucose-stimulating activity does not seem to be solely due to polyphenol content since methanol extract, with high amount of polyphenol content (9.5 ± 0.1 g kg(-1)), did not stimulate higher glucose uptake activity when compared to water extract.

Keywords: Diabetes; EAT cells; Glucose uptake; Tinospora cordifolia.

Fig. 1

Effect of aqueous (a), ethanol (b) and methanol (c) extracts of T. cordifolia on glucose uptake in EAT cells: EAT cells (8 × 10⁷) were incubated with different extracts of T. cordifolia, 40 μl of 1 mM 2-NBDG and volume made to 400 μl with KRH buffer (see Materials and methods). Uptake was measured after cell lyses using a spectrofluorimeter. Values are given as net glucose uptake in nM and are expressed as mean ± SD of quadruplicates of two independent experiments. Values are significant at ** P < 0.01 and *** P < 0.001 when compared to control (8 × 10⁷ EAT cells + 40 μl of 1 mM 2-NBDG)