Isolation,Purification,in Vitro Activity Of Flavonoids From Chenopodium Quinoa Chaff

As a by-product of Quinoa,Quinoa chaff often treated as residue in the processing process and not fully utilized.In this study,the extraction technology,purification methods,purification conditions,antimicrobial and antioxidant activity of flavonoids from Quinoa chaff were studied systematically.The research content is as follows:Based on the single-factor experiment,solid/liquid ratio,ethanol concentration,the ultrasonic extraction time and ultrasonic temperature were used as experimental factors,and the yield of flavonoid from Quinoa chaff was optimized by Box-Benhnken central combination design and response surface methodology.The results showed that the optimal extraction conditions of flavonoids from Quinoa chaff were as follows: 56% ethanol,the solid/liquid ratio of 1:20 g/m L the ultrasonic time of 14 min and the ultrasonic temperature of 58 ?.Under this condition,the extraction rate of flavonoids was(0.821±0.012)%.The effects of seven macroporous adsorption resins(D101,HPD450,HPD750,HPD950,NKA9,X-5 and AB-8)on the static adsorption and desorption of flavonoids from Quinoa chaff were studied.The best macroporous resin was HPD950.The main purification process factors were sample concentration,sample loading,column pH,ethanol concentration and desorption volume.The optimum conditions of flavonoids from Quinoa chaff were obtained: sample solution concentration 0.5 mg /m L,sample loading volume 35 m L,sample solution pH 6.0,ethanol concentration 75%,desorption volume 180 m L.Under these conditions,the purity of flavonoids increased from(13.0±0.30)% to(68.0±0.50)%,and the recovery rate was(77.4±0.27)%.The purified flavonoids of quinoa chaff were analyzed by high performance liquid chromatography(HPLC),and nine compounds were detected.By comparing with standard flavonoids,four compounds of quercetin,quercetin,rutin and quercetin in the purified flavonoids ofquinoa chaff were identified.The inhibitory effect of flavonoids from Quinoa chaff on Escherichia coli,Staphylococcus aureus and Bacillus subtilis was studied by plate counting method.The bacteriostatic performance of rhizopus was investigated by the bacteriostatic circle method.The effects of concentration,pH and heat treatment of purified flavonoids of quinoa chaff on the bacteriostasis were investigated.The results showed that the flavonoids of Quinoa chaff had better inhibitory effect on bacteria,but no obvious inhibitory effect on fungi.Under weak acid conditions,the purified flavonoids of quinoa chaff had stronger bacteriostasis ability.When the temperature was 70 ?,the flavonoids of quinoa chaff still have certain bacteriostasis,and have better thermal stability.The purified flavonoids from quinoa chaff have good scavenging ability to hydroxyl free radical,superoxide anions free radical and DPPH free radical.When the concentration of flavonoids was 125 ?g/m L,the DPPH scavenging rate was(46.7 ± 0.60)%,the superoxide anion scavenging rate was(39.2±0.70)%,and the hydroxyl radical scavenging rate was(35.39±0.86)%.