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Effect of gypenosides on porcine pancreatic lipase (PL) activity was determined in vitro. Gypenosides inhibited the PL activity in a dose-dependent manner at the concentrations of 0-1.0 mg/ml. The Lineweaver-Burk plots for gypenosides indicated that the inhibition on PL by gypenosides was noncompetitive. The conformation of PL was investigated by means of circular dichroism and fluorescence. The result revealed the decrease in α-helix contents, increase in β-sheet and the decrease in fluorescence intensity after gypenosides treatment. The incorporation of cholesterol into micelles was inhibited by gypenosides. A complex was observed by transmission electron microscopy, indicating interaction between cholesterol and gypenosides which led to the decrease in cholesterol micelle solubility. The result revealed the fact that gypenosides played a role in inhibiting PL activity and reducing intestinal cholesterol absorption via inhibition of micelle formation. [ABSTRACT FROM AUTHOR]

This study investigated the hypocholesterolaemic effects of bitter melon aqueous extracts (BMAE) in vitro, the inhibitory effects of BMAE on pancreatic cholesterol esterase (CEase) and incorporation of cholesterol into micelles were investigated. BMAE decreased the in vitro micellar solubility of cholesterol in a dose-dependent manner. The conformation of CEase was investigated by means of circular dichroism (CD) and fluorescence. The result revealed the decrease of α-helix contents, increase of β-sheet and exposure of aromatic amino acid residuals. The incorporation of cholesterol into micelles was inhibited by BMAE. A complex was observed by transmission electron microscopy (TEM), which indicated interaction between cholesterol and BMAE. The result revealed that BMAE can play a role in decreased intestinal cholesterol absorption via inhibition of CEase, and of micelle formation. [ABSTRACT FROM AUTHOR]