Hexane fraction of Citrus aurantium L. stimulates glucagon-like peptide-1 (GLP-1) secretion via membrane depolarization in NCI-H716 cells

Citrus species have been used traditionally as a medicinal herb in oriental pharmacology. Here, we reported on the anti-diabetic function of Citrus aurantium L. (CA). The hexane fraction of CA (HFCA) stimulates NCI-H716 cells and results in the secretion of glucagon-like peptide-1 (GLP- l). Because it regulates insulin secretion in pancreatic beta-cells, GLP-1 has been used for the treatment of type II diabetes mellitus. Hence, we carried out a series of experiments to demonstrate the functions of HFCA against diabetes mellitus at the molecular level. Four fractions of CA were used in a GLP-1 assay. The GLP-1 ELISA assay was performed to measure the concentrations of GLP-1 after treatment with the four fractions of CA. The hexane fraction showed the best results and was chosen for the microarray analysis in the genome wide analysis. Through the analysis, it was found that voltage-gated potassium (Kv) channels drove membrane depolarization and then influenced Ca2+ currents in NCI-H716 cells. These results suggest this is a new oriental herbal drug that has proven effects for the remedy of type II diabetes mellitus.