Chemical constituents of Rotala rotundifolia Triterpenoids and sterols from Melia azedarach and their anti-diabetes activities Effect of berberine on glucokinase and its related glucose metabolism in rats with insulin-secretion deficiency Effects of berberine on expression of hepatocyte nuclear factor 4α and glucokinase activity in mouse primary hepatocytes Effects of Rehmannia glutinosa oligosaccharides on activity and gene expression of hepatic glycometabolic key enzymes in type 2 diabetic rats Effects of Rehmannia glutinosa oligosaccharides on activity and gene expression of hepatic glycometabolic key enzymes in type 2 diabetic rats