Extraction,Purification And Antioxidant Activity Of Lignans From Linseed Meal

Flax(Linum usitatissimum L.)belongs to the family flax,which is an annual herb.Its mature seed-linseed contains a lot of lignans.Modern pharmacological studies have revealed that linseed lignans possesses antioxidant,antineoplastic,inhibiting DNA and RNA synthesis,antiviral,fungal and so on.With the backward of cognition,traditional linseed is only used to extract linseed oil.Linseed meal,a by-product of linseed oil extraction,is often used as organic fertilizer or poultry feed,which resulting in a colossal waste of resources.Therefore,the full development and utilization of linseed meal has certain practical value and economic value.In this work,the high performance liquid chromatography(HPLC)detection,extraction process,purification process and in vitro antioxidant activities of SDG from linseed meal were investigated.The aim was to improve its yield and purity,and provide theoretical and technical support for the further development and utilization of linseed meal.The main results were as follows:1.Linseed lignans(SDG)were extracted from linseed meal by ethanol reflux and ultrasonic-assisted aqueous two-phase method.The optimal extraction conditions of ethanol reflux method were: 68% ethanol,extraction temperature 68 °C,liquid-to-solid ratio 24 mL/g,extraction time 3.0 h,the yield of SDG was 20.31±0.07 mg/g,purity 18.9%.The optimal conditions of ultrasonic-assisted aqueous two-phase method were as follows: 9.0 wt% sodium hydroxide,30.0 wt% isopropanol,extraction time 39 min,extraction temperature 40 °C,liquid to solid ratio 52 mL/g,the yield of SDG was 19.04±0.08 mg/g,purity 21.5%.2.The ethanol extract(SDG-EA-C)and aqueous two-phase extract(SDG-ATPS-C)were purified by macroporous resin.Purification of SDG-EA-C: D101 macroporous resin,sample volume,sample concentration and sample flow rate were 110 mL,3.64 mg/mL and 1.0 mL/min,respectively.The column was cleaned with ultra-pure water.The elution solvent,elution volume and elution flow rate were 25% ethanol,125 mL and 1.0 mL/min,respectively.The recovery rate of SDG-EA-C purified product(SDG-EA-P)was 81.67%,the purity was increased from 18.9% to 69.7%,increased 50.8%.Purification of SDG-ATPS-C: AB-8 macroporous resin,sample volume,sample concentration and sample flow rate were 140 mL,3.18 mg/mL and 1.0 mL/min,respectively.The column was cleaned with ultra-pure water.The elution solvent,elution volume and elution flow rate were 25% ethanol,90 mL and 1.0 mL/min,respectively.The recovery rate of SDG-ATPS-C purified product(SDG-ATPS-P)was 78.4%,the purity was increased from 21.5% to 73.9%,increased 52.4%.3.Semi-preparative HPLC was used to purify SDG-EA-P.Megres C18(30 mm x 250 mm,10 m)Chromatographic column,acetonitrile(A)-0.1% phosphoric acid(B)as mobile phase,detection wavelength 280 nm,column temperature 30 °C,injection volume 2.0 mL(84 mg),flow rate 35 mL/min,elution procedure for 0~5 min,15%~20% A,5~10 min,20%~25% A,10~16 min,25% A.The SDG purity and recovery were 98%,93.2% respectively.4.The in vitro antioxidant activity of linseed lignans showed: crude extracts and purified products of linseed lignans had scavenging activity for DPPH,ABTS and OH free radicals,among which the scavenging capacity for DPPH,ABTS free radicals was stronger,while the scavenging activity for OH free radicals was weaker.Lignans has some protective effect on the oxidative damage of plasmid DNA induced by hydrogen peroxide in the range of 0.06~0.40 ?g/mL,but it has no protective effect on the oxidative damage of plasmid DNA induced by hydrogen peroxide in the range of 0.06~0.12 ?g/mL.