FRACTIONS FROM RUELLIA TUBEROSA L. EXTRACT IMPROVES GLUCOSE UPTAKE IN TNF-? INDUCED INSULIN RESISTANT MOUSE FL83B HEPATOCYTES

Background and objectives: Diabetes mellitus (DM) is characterized by insulin resistance, caused by inadequate production of insulin or by the ineffectiveness of insulin activity. Ruellia tuberosa L. (RTL) is a plant herb and has been used as folk medicine for the treatment of diabetes in Asian countries for decades. The previous study confirmed that ethyl acetate extract of RTL possesses hypoglycemic potential in diabetic rabbits. However, the detail mechanism was still unclear. The aim of this study was to investigate the effect of the ethyl acetate fraction (EAF) from RTL methanol extract on cytotoxicity and glucose uptake in tumor necrosis factor-alpha (TNF-a) induced insulin resistant mouse FL83B hepatocytes. Methods: RTL was first extracted with methanol, and followed by partitioned with n-hexane and ethyl acetate, respectively. The ethyl acetate layer was then isolated into eight fractions by sephadex LH20 column chromatography. The EAF containing eluents were collected and lyophilized to be powder samples. MTT assay was conducted to measure the cytotoxicity of EAF in FL83B cells. EAF was further co-incubated with TNF-a treated FL83B cells, and flow cytometry was used to assess glucose uptake ability in cells. Results: The results showed that no significant cytotoxicity effect was observed for eight EAFs at the concentration of 25 μg/ml in FL83B cells. Moreover, EAF2, EAF3, EAF5 significantly enhances the uptake of 2-NBDG in TNF-a treated FL83B cells. Conclusions: In conclusion, the present study suggests that RTL may alleviate insulin resistance without cytotoxicity and has potential for developing into anti-diabetic drugs or dietary supplements.