Study On The Regulation Of Lipid Metabolism By Nymphaea Hybrid Extracts

With the enhancement of living standard and the change of people’s lifestyle,obesity has become a public health problem and its incidence shows increasing tendency in worldwide.Natural products from plant sources can reduce weight gain through inhibition of fat absorption and synthesis,promotion of fat metabolism and inhibition of appetite.Nymphaea hybrid belongs to Nymphaeaceae family with the genus of Nymphaea which is rich in polyphenols,flavonoids,anthocyanins and so forth.Nymphaea hybrid has possessed many bioactive effects.In this paper,active monomers were obtained by using Preparative High-Performance Liquid Chromatography(Prep-HPLC)on the basis of inhibition of pancreatic lipase(PL).And the preventive effect of Nymphaea hybrid extract(NHE)on mice with high fat diets-induced obesity was investigated.Besides,the impact of gut microbiota on the obese mice was also determined.The research conclusions are as follows:(1)Ten components were isolated from NHE by Prep-HPLC.On the basis of inhibiting PL activity experiment in vitro,the chemical structure of two active monomers were identified by the method of mass spectrometry and nuclear magnetic resonance.The results suggested that the active monomers were identified as phenolic compounds,β-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-D-glucose(Corilagin)and 4’,5,7-Trihydroxyflavanone-5-O-β-D-Glucopyranoside(Helichrysin A),which were isolated from Nymphaea hybrid for the first time,and their contents in NHE were 24.94 mg/g and 12.34 mg/g respectively.(2)The optimal reaction parameters of PL activity inhibitting effect were determined as reaction time(10 min),pH(7.5)and temperature(37℃),by which,NHEA could effectively inhibit PL activity(IC50 2.09 mg/mL).Among the ten components isolated from NHE,six components showed strong inhibiting effects on PL to some extent.And Corilagin showed the strongest inhibition activity(IC50 0.64 mg/mL),closely followed by Helichrysin A(IC50 0.70 mg/mL).What’s more,inhibition rates of pancreatic lipase were corelated with total phenols contents(R2=0.885).(3)The anti-obesity effect of NHE was investigated by the model of preventive obese mice which was induced by high fat diets.The results showed that as compared with model control group,the high dose of NHE(400 mg/kg/BW)could significantly reduce the body weight,epididymal fat,perirenal fat and liver,and the contents of serum TG,TC(p<0.05),increase the contents of fecal lipid,TG(p<0.05)and lower PL activity(p<0.01).And NHE could effectively enhance liver SOD activity(p<0.05),reduce the MDA content in liver(p<0.05)and TNF-α,IL-6,MCP-1 in adipose tissue(p<0.01).(4)The effects on gut microbiota of the obese mice were determined by high-throughput sequencing.The results showed that as compared with model control group,NHE could increase the diversity and abundance,and change the composition of gut microbiota in high-fat diet mice,which were specifically showed effects on reducing the ratio of Firmicutes and Bacteroidetes(F/B value),increasing the probiotic’s amount of Lactobacillus and Akkermansia muciniphila,and reducing the harmful bacteria’s amount of Desulfovibrio.But NHE couldn’t increase the amount of Bifidobacterium.To sum up,NHE possesses bioactive effects on preventing obesity,reducing oxidative stress,and relieving chronic inflammatory of fatty liver tissue by the way of inhibiting PL activity and changing the composition of gut microbiota in dose-dependent manner.It is speculated that Corilagin and Helichrysin A are two characteristic compounds identified in NHE.Therefore,it provides a certain scientific foundation and theoretical direction for the exploration and utilization of Nymphaea hybrid as product with function of weight-loss and lipid-lowering.