Fructus Corni suppresses hepatic gluconeogenesis related gene transcription, enhances glucose responsiveness of pancreatic beta-cells, and prevents toxin induced beta-cell death

Ethnopharmacological relevance: Fructus Corni, the fruits of Cornus officinalis Sieb. etZucc., is one important ingredient in Quei Fu Di Huang Wan, a Chinese herbal mixture. Aim of the Study: In the present study, additional anti-diabetic actions of Fructus Corni on transcriptional regulation of hepatic gluconeogenesis or beta-cell functions were investigated. Materials and methods: Insulin mimetic action of Fructus Corni on dexamethasone and 8-bromo-cAMP induced phosphoenolpyruvate carboxykinase (PEPCK) expression in H4IIE cells was investigated. Besides, BRIN-BD11 cells were used to evaluate both insulinotropic and beta-cell protective effect of Fructus Corni. Results: Firstly, both methanol extract (CO-W-M) and fraction (CO-W-M2) had potent insulin mimic activity on PEPCK expression. Secondly, possibility of both loganin and ursolic acid as the responsible compounds was excluded. Moreover, indication of the existence of phenolic compounds in CO-W-M2 was noticed. in the presence of CO-W-M2, not only was the viability of BRIN-BD11 cells treated with alloxan, streptozotcin, or cytokine mix all significantly increased but also glucose-stimulated insulin secretion was potentiated. Conclusions: The ability of CO-W-M2 to reduce gene expression for hepatic gluconeogenesis, to protect beta-cell against toxic challenge, and to enhance insulin secretion strengthen the role of Fructus Corni in diabetes therapy. (C) 2008 Elsevier Ireland Ltd. All rights reserved.