Content Analysis of Chenopodium formosanum (Djulis) Collected From Two Production Areas and Evaluation of Their Ability to Improve Insulin Resistance

Abstract

Background This study compared the contents of extracts of Chenopodium formosanum (Djulis) originating from 2 aboriginal areas (Kaohsiung and Taitung, Taiwan) and evaluated their efficacy in ameliorating insulin resistance in vitro. Methods First, we analyzed the anti-oxidant compositions and activity, and α-glucosidase, α-amylase inhibitory effects of 2 Djulis and their extracts, and then evaluated the ability of the 2 extracts to ameliorate insulin resistance in HepG2 cell. To do this, we incubated the cells in DMEM medium spiked with insulin and TNF-α. Results Taitung Djulis extract (TDE) had higher concentrations of flavonoids and polyphenols than the Kaohsiung Djulis extract (KDE). However, KDE had a greater anti-oxidative effect and greater ability to inhibit α-glucosidase and α-amylase inhibitory than TDE. In the cellular experiment, insulin promoted cell glucose uptake, and increased the protein expression of glucose transporter-2 (GLUT-2). However, when adding TNF-α with insulin, TNF-α worsened insulin-stimulated glucose metabolism. This might be associated with TNF-α induced mitogen-activated protein kinases (MAPKs) expression. Treating the insulin resistant cells with either TDE or KDE significantly reversed the effect of TNF-α on glucose uptake and related protein expressions. Conclusion Although both TDE and KDE reduced TNF-α-induced insulin resistance, KDE was found to be more potent. KDE might have more bioactivity or other undetected components that lead to more efficiency than TDE. Taken together, Djulis extract could potentially be used to control insulin resistance.