Abstract

Cymbopogon citratus has been reported to have hypoglycaemic and antidiabetic activities. This study evaluates the insulinotropic properties of C. citratus via gene expression. C. citratus was administered to normal rats as pulverized leaves (2, 10 and 30%) mixed with animal feed for one week; as aqueous and ethanol extracts at a dosage of 30 and 100 mg/kg body weight for 30 days; and as isolated saponins, flavonoids and tannins at 30 µg/kg for 7 days. Animals were sacrificed after the treatment protocol and organs of interest removed for analysis. Gene expression analysis of C. citratus was based on polymerase chain reaction (PCR) for glucagon like peptide-1 (GLP-1), insulin, glucose transporter 4 (GLUT4) and potassium ion gated channel (KCNJ5), using isolated mRNA. Results showed that the extracts and phytochemicals fractions (particularly flavonoids) of C. citratus increased insulin gene expression, whereas only the whole plant feeding of normal rats increased GLP-1 gene expression in a dose-dependent manner. Administration of plant extracts increased GLUT-4 expression while phytochemical fractions of C. citratus did not alter the expression of KCNJ5 gene. It can be concluded that the pharmacology of C. citratus, especially the whole plant and the aqueous and ethanol extracts, favours the up-regulation of some insulinotropic genes.

Key word: Insulinotropic properties, Cymbopogon citratus, gene expression, insulin, saponins, flavonoids, tannins.