Study The Simultaneous Extraction Technology Of Essential Oils And Flavonoids From Leaves Of Abutilon Theophrasti Medic.and Antioxidant Activity Of Flavonoids

Abutilon theophrasti Medic.belongs to the annual inferior bush shape herbaceous plant,widely distributed in our country and most parts of the world.Whole plants are enriched in a variety of biological active ingredients.As secondary metabolites,essential oils?EOs?and flavonoids are found widely in A.theophrasti Medic.leaves,which have been demonstrated to have multiple pharmacological activities,and used as natural antioxidant additive in the food and industrial production.In the present study,applied deep eutectic solvents?DESs?as extraction solvent,ultrasonic/microwave-assisted simultaneous distillation and extraction?DES-UMASDE?method for the extraction of volatile compounds?essential oils,EOs?and non-volatile flavonoids?quercetin,QU;kaempferol,KA;isorhamnetin,IS?from leaves of A.theophrasti Medic.Furthermore,the parameters of experimental process were optimized.Catalytic conversion,enrichment and separation of target flavonoids in the DESs extraction solutions by strong acid type cation exchange resin and macroporous adsorption resin were studied,and their antioxidant activities were preliminary evaluated.Moreover,this study provided strong theoretical basis and technical support for rational development and utilization of A.theophrasti Medic.resources.1.Deep eutectic solvents-based ultrasonic/microwave-assisted simultaneous distillation and extraction?DES-UMASDE?was developed for essential oils?EOs?and three main flavonoids?quercetin,QU;kaempferol,KA;isorhamnetin,IS?from A.theophrasti Medic.leaves for the first time.The important parameters were optimized using Box-Behnken design based on single factor test and essential oils?EOs?were analyzed by gas chromatography-mass spectrometry?GC-MS?.Screening of DESs:choline chloride-lactic acid,mole ratio:1:2,water content:20%.The optimal extraction parameters by Box-Behnken design?BBD?combined with response surface methodology?RSM?:ultrasonic power:50 W,liquid-solid ratio:31 mL/g,extraction time:12 min,microwave power:518 W.The yields of quercetin,?QU?;kaempferol,?KA?;isorhamnetin?IS?obtained under the optimum conditions were 1.65±0.05,1.82±0.08,1.21±0.06 mg/g,respectively;these are1.02-,1.14-and 1.05-fold higher,respectively,than those obtained by conventional ethanol heat reflux extraction?HRE?.The extraction time for the equilibrium yields of three main flavonoids using DES-UMASDE was 36.2%,49.6%,61.8%,and 66.4%,respectively,less than the corresponding times using DES-MAE,DES-ultrasonic-assisted extraction?DES-UAE?,ethanol UAE?E-UAE?and ethanol HRE?E-HRE?.DES-UMASDE has obvious advantages on three main flavonoids in A.theophrasti Medic.leaves.The yield of essential oils?EOs?obtained using DES-UMASDE was 0.184±0.008%,i.e.,1.41-fold higher than that obtained by conventional hydrodistillation extraction?HDE?.The extraction time for the equilibrium yields of EOs using DES-UMASDE is 36.2%,49.6%,50.5%,and 70.8%lower than those for DES-MASDE,water-UMASDE,water-MASDE,and HDE,respectively.Meanwhile,GC-MS chromatographic analysis results show that the main components of essential oils?EOs?obtained from DES-UMASDE and HDE are basically the same.The extraction yield with DES-UMASDE was the highest,and DES-UMASDE accelerates the isolation of essential oils?EOs?from A.theophrasti Medic.leaves without causing major changes in the EOs composition compared with HDE.Consequently,the developed method DES-UMASDE as a novel extraction technology,which was expected to be applied to simultaneous extract volatile and nonvolatile active ingredients from other plants.2.In this work,cation exchange resins were used as acidic catalysts to transform main flavonoids from DESs extraction solutions.Compared with the catalytic activities of NKC-9,D061,D072,DLT,D113,and D151 resins.It turned out that the resin type markedly affected the efficiency of transformation,and efficiency of NKC-9 type resin was the best.The application of cation exchange resins highlights the essence of green chemistry compared with acid hydrolysis.3.Efficiently enrichment and separation of quercetin,?QU?;kaempferol,?KA?;isorhamnetin?IS?after the catalytic transformation reaction is very important.Six different type macroporous adsorption resin?HP20,AB-8,HPD400,X-5,D101,and NKA-9?was used,and the result shows that six type macroporous adsorption resin was suitable to enrich and separate the above three flavonoids efficiently.Among them,AB-8 type resin was the best in enrichment and separation,consequence with the recovery yields of quercetin,?QU?;kaempferol,?KA?;isorhamnetin?IS?achieved 78.92%,86.34%,and 82.66%,respectively.The vitro antioxidant activities of total flavonoids treated by different type macroporous adsorption resins were studied.The experimental results showed that FRAP experimental value was 1.025 mmol FeSO₄/g;the determination of TEAC value was 0.437 mmol Trolox/g in ABTS test;The content of total flavonol glycosides was 26.2 mg/g and total flavonoids had the strongest antioxidant activity treated by AB-8 resin.DPPH radical scavenging ability was83.6%,which slightly lower than Vc?95.7%?,and IC₅₀ value was 0.90 mg/m L.