Study On Extraction And Application Of Polyphenols From Perilla Seed Hull

Perilla frutescens is an annual medicinal and edible homologous herb of Labiatae family.It is a treasure of the whole body which contains rich nutrients and bioactive substances.It has high economic value and has received worldwide attention.In this paper,the extraction and purification technology of polyphenols from perilla seed hull were studied.The antioxidant,bacteriostatic and cytotoxic activities of polyphenols from perilla seed hull were determined,and the fresh-keeping effect of polyphenols in grape was further studied.The main results were as follows:（1）On the basis of single factor experiments,the ultrasonic-assisted extraction of polyphenols from perilla seed hull was optimized by response surface methodology（RSM）.The optimum conditions were as follows:liquid-solid ratio 22:1 mL/g,extraction time 47 min,extraction temperature 70 C.Under these conditions,the contents of polyphenols,flavonoids,rosmarinic acid and proanthocyanidins were 25.11,45.68,10.56 and 5.08 mg/g,respectively.The results of scanning electron microscopy（SEM）showed that the cell wall surface of perilla seed hull was slightly ruptured and porous after ultrasonic treatment,which promoted the release of active substances into the extraction solvent to increase the content.（2）The extraction and antioxidant activity of polyphenols from perilla seed hull of different varieties were studied.The results showed that there was a significant positive correlation between antioxidant capacity and the contents of polyphenols,flavonoids and rosmarinic acid.The contents of polyphenols,flavones and rosmarinic acid in CLX,GS and YX3 were relatively high,and the antioxidant capacity was also high,which can be used as the main source of polyphenols from perilla seed hull.（3）The optimal macroporous resin was obtained by static adsorption and desorption tests,which the best resin was XDA-8,the adsorption rate and desorption rate were 58.18%and72.19%respectively.The optimum process were determined by dynamic adsorption and desorption experiments as follows:sample concentration of 6 mg/mL,sample flow rate of 4BV/h,ethanol volume fraction of 60%,elution flow rate of 2 BV/h,eluent dosage of 8 BV.The purity of perilla seed hull polyphenols increased from 13.93%to 30.34%after purification,increased by 2.18 times.Four main polyphenols were identified by HPLC/MS,namely luteolin 7-O-glucoside,apigenin 7-O-diglucuronide,scutellarein7-O-glucuronide and rosmarinic acid.（4）The antioxidant ability of perilla seed hull polyphenols and Vc was determined.The IC₅₀0 values of DPPH free radical scavenging were 1184,1085 and 1341μg/mL,ABTS free radical scavenging was 18.80,10.09 and 10.40μg/mL,and hydroxyl free radical scavenging was 1184,1085 and 1341μg/mL,respectively.The total reducing power was linearly enhanced.The results of bacteriostasis test showed that perilla seed hull polyphenols had no inhibitory effect on Yeast and Aspergillus niger,but only on Escherichia coli,Staphylococcus aureus and Bacillus subtilis.The minimum inhibitory concentration（MIC）for these three bacteria were 0.625,1.25 and 0.3125 mg/mL,respectively.The results of cytotoxic activity test showed that the LC₅₀0 value of polyphenols in perilla seed hull was more than 1000μg/mL,which had almost no lethality to sea prawn and no anticancer activity.（5）The application of perilla seed hull polyphenols in grape preservation experiment showed that the polyphenols in perilla seed hull could significantly delay the decay of grapes,reduce the loss of nutrients,and prolong the shelf life for about 5 days,and effectively maintain the storage quality of grapes.