Study On The Extraction Of Polyphenolic Compounds By Deep Eutectic Solvent

As an important secondary metabolite in plants,polyphenolic compounds have many functions,such as antioxidant,anti-tumor,hypoglycemic and lipid-lowering.They are widely used in the development of health food.Deep eutectic solvent is a new kind of solvent,which has the advantages of non-toxicity,environmental protection and high efficiency.It is gradually applied to the green extraction of natural products.In this study,eleven deep eutectic solvents were used to extract phenolic acid(chlorogenic acid)from tobacco leaves and flavonoids from chickpea(ononin,sissotrin,formononetin,and biochanin A)by ultrasound-assisted extraction.Response surface methodology was used to optimize the main extraction parameters.Macroporous resin adsorption was used to enrich and separate the extracts,and the extracts were obtained.The antioxidant activity in vitro was tested.The results are as follows:1.Extraction of phenolic acids from tobacco by deep eutectic solvent(1)The eutectic solvent suitable for extracting phenolic acids from tobacco was choline chloride-malic acid(molar ratio is 1:1),and the extraction effect was better than 80%methanol aqueous solution.(2)Through single factor experiments,the main extraction parameters were optimized.The optimum conditions were as follows:water content of eutectic solvent was 40%,extraction temperature was 50?,extraction time was 30 min,solid-liquid ratio was 40 mg/mL.(3)On the basis of single factor experiment,the technological parameters of extracting phenolic acid compounds from tobacco leaves by deep eutectic solvent were optimized by Box-Behnken design principle.The optimum extraction conditions were as follows:water content of deep eutectic solvent was 41%,extraction temperature was 60?,extraction time was 40 min,material-liquid ratio was 20mg/mL.Under the optimum conditions,the extraction amount of tobacco phenolic acid was 17.69±0.23 mg/g through three validation tests.(4)In vitro antioxidant activity test showed that extract of tobacco phenolic acid had good scavenging effect on DPPH free radical and ABTS~+free radical,and the scavenging ability was positively correlated with its mass concentration.Compared with positive control BHT and VC,DPPH and ABTS~+scavenging activity of extract were better than BHT,but lower than VC.2.Extraction of flavonoids from chickpea by deep eutectic solvent(1)The eutectic solvent suitable for extracting flavonoids from chickpea was choline chloride-1,4-butanediol(molar ratio 1:5),and the extraction effect was better than 60%methanol aqueous solution.(2)Through single factor experiments,the main extraction parameters were optimized.The optimum conditions were as follows:water content of eutectic solvent was 30%,extraction temperature was 50?,extraction time was 30 min,solid-liquid ratio was 40 mg/mL.(3)On the basis of single factor experiment,the technological parameters of extracting flavonoids from chickpea by deep eutectic solvent were optimized by Box-Behnken design principle.The optimum extraction conditions were as follows:water content of deep eutectic solvent was 32%,extraction time was 35 min,extraction temperature was 59?,and material-liquid ratio was 40 mg/mL.Under the optimum conditions,the extraction amount of chickpea flavonoids was 6.83±0.11 mg/g through three validation tests.(4)In vitro antioxidant activity test showed that the extract of chickpea flavone had excellent scavenging effect on DPPH free radicals and ABTS~+free radicals,and the scavenging ability was positively correlated with its mass concentration.Compared with positive control BHT and VC,DPPH and ABTS~+scavenging activity of extract were significantly better than BHT,but lower than VC.