High-efficient Extraction Of Total Polyphenols From Eucommia Ulmoides Leaves And Its Application Research

Eucommia ulmoides Oliver,known as Sixian,Sizhong and so on,is traditionally medicine used as skin,which is a precious traditional Chinese medicine in China.Eucommia ulmoides leaves and bark have very similar chemical compositions and pharmacological activities,and the content of polyphenols compounds in leaves is higher than that in bark.Total polyphenols have many pharmacological effects,such as anti-oxidation,anti-aging,anti-radiation,anti-bacterial,anti-inflammatory and so on.They are called "the seventh nutrients",which have broad market prospects in food,cosmetics and pharmaceutical industries.In this paper,based on optimizing the extraction process of total polyphenols from Eucommia ulmoides leaves,the activities and efficacy of the extract were studied,which could provide theoretical basis for the development and comprehensive utilization of Eucommia ulmoides leaves in the field of functional food and cosmetics.1.The extraction technology of total polyphenols from Eucommia ulmoides leaves was optimized by ultrasound-microwave assisted method.Experiment was conducted to investigate the effects of 6 factors,such as ethanol volume fraction,solid-liquid ratio,ultrasound power,ultrasound extracting time,microwave power,and microwave extracting time on the yield of total polyphenols from Eucommia ulmoides leaves by Plackett-Burman design.After screening the four significant factors including ethanol volume fraction,solid-liquid ratio,microwave power and ultrasound extracting time,the process optimization was carried out by the steepest ascent design and response surface.The optimal extraction conditions were as follows:ethanol volume fraction 46%,solid-liquid ratio 1:20.70(g:mL),the microwave power 154 W and ultrasound extracting time 31 min.Under this condition,the yield of total polyphenols was 8.491%,which has been improved significantly compared with the traditional extraction method.2.The antioxidant and anti-carbonylation activities of EULTPE were investigated.Taking Vc and BHT as positive controls,Taking Vc and BHT as positive controls,the scavenging abilities of EULTPE on-DPPH radical,2,2-diazido-bis-(3-ethylbenzothiazolin-6-sulfonic acid)diammonium salt radical(ABTS·),hydroxyl radical(·OH)were investigated and the results are as follow:In a certain concentration range,the effect of scavenging radical is positively correlated with the mass concentration.The scavenging capacity for ·DPPH radical is stronger than BHT and weaker than Vc;The scavenging capacity for ABTS· and ·OH is slightly weaker than BHT and Vc.In addition,the EULTPE shows the good anti-carbonylation effect.In a test concentration range,the scavenging capacity for carbonylation is positively correlated with the mass concentration.It has obvious effect of scavenging carbonyl substances and can better protect the protein in red blood cells from crosslinking with carbonyl substances in the concentration range of 100 mg/L to 500 mg/L.3.Taking gentamicin sulfate as positive control,the inhibitory effects of EULTPE on Salmonella and Staphylococcus aureus were investigated.The results showed that the EULTPE had broad-spectrum antibacterial activity and good inhibitory effect on salmonella and staphylococcus aureus.The MIC and MBC are as follow:MIC:salmonella 0.700 mg/mL,staphylococcus aureus 0.350 mg/mL;MBC:salmonella 1.400 mg/mL,staphylococcus aureus 0.700 mg/mL.The antibacterial activity of EULTPE was studied by simulating different food substrates and different food processing conditions.The results show that food matrix(protein and carbohydrate)can affect the inhibitory effect of EULTPE on Salmonella and Staphylococcus aureus.In medium containing high concentration of beef extraction(protein)and carbohydrate(water soluble starch),the MIC value of EULTPE was increased and the inhibitory effect of EULTPE on Salmonella and Staphylococcus aureus were weakened.Increasing protein concentration in medium can shorten the lag time of EULTPE to Salmonella,and the effect is negatively correlated with the increase of concentration.Low protein concentration and low carbohydrate concentration can improve the maximum specific growth rate of Salmonella under the effect of EULTPE.Food processing conditions(temperature and pH)can also affect the inhibitory effect of EULTPE on Salmonella and Staphylococcus aureus.High temperature and high pH can increase MIC value of EULTPE and weaken its bacteriostatic effect.With the increase of treatment temperature,the lag time and maximum specific growth rate of Salmonella and Staphylococcus aureus decreased.