Abstract: In the study,Nymphaea hybrid extract and its fractional phases (petroleum ether phase,ethyl acetate phase,nbutyl alcohol phase and water phase) were obtained through ultrasonic extraction and fractional extraction.The inhibitory effects of Nymphaea hybrid extract and its fractional phases on pancreatic lipase were analyzed under the optimum reactive conditions and the inhibitory type was determined by using enzyme kinetic analysis.The results showed that the optimal inhibitory effect was reached when the response time was 10 min,the pH was 7.5 and the temperature was 37 ℃,and under this reaction condition the ethyl acetate phase of Nymphaea hybrid could effectively inhibit the ability of pancreatic lipase and its halfinhibitory concentration (IC50) on pancreatic lipase was 2.09 mg/mL.According to the research of enzyme kinetic analysis,the inhibitory type of ethyl acetate phase was reversible mixed inhibition,and the inhibitory constants (Ki and Ki’) were 0.95 mg/mL and 8.79 mg/mL.What’s more,the correlation between content of total polyphenols and inhibition rate of pancreatic lipase was strong (R2=0.885).Therefore,the ethyl acetate phase of Nymphaea hybrid can play the role of weight reducing factor by inhibiting the activity of pancreatic lipase,and the key compounds may be phenolics.

Key words: Nymphaea hybrid, pancreatic lipase, ethyl acetate phase, halfinhibitory concentration, inhibitory type, inhibitory constant