| Purslane(Portulaca oleracea L.)is an annual succulent herbaceous in the family Portulacaceae,and is classified as one of the 101 kinds of wild plants of homology of medicine and food by Ministry of Public Health of China.Purslane is rich in nutrients,and contains bioactive substances,such as polysaccharide,polyphenol,flavonoid and alkaloid,that can remove free radicals and prolong life.This thesis chose purslane as an experimental material and did a systematic study on the major nutritional compositions,the content of bioactive substances in different organs of purslane and their antioxidant activities,and the optimization of the ultrasonic wave extraction process of flavonoid and alkaloid from purslane by means of response surface methodology.The research contents and results are as follows:1.The major nutritional compositions of purslane.The content of moisture,ash,Vc,crude protein,soluble sugar of purslane were determined as well as content of N,P,Ca,Mg,Cu,Zn,Fe and Mn.The conclusion is that purslane is a green,safety,nutritive and edible wild vegetable with high fiber,high protein and low fat.2.The content of polysaccharide substance extracted from whole plant,root,stem,leaf and flower of purslane and its antioxidant activities.(1)The polysaccharides were extracted and purified from purslane by ultrasonic wave extraction,followed by ethanol precipitation and anhydrous ethanol,ether and acetone washing.The content of polysaccharide extracted from different organs of purslane was determined by phenol-sulphuric acid method.The results of polysaccharids content showed that: stem> whole plant> leaf,flower> root,leaf and flower contain similar amount of polysaccharide content.The polysaccharide content of stem,whole plant,leaf,flower and root of purslane is 34.87 mg/L,31.13 mg/L,24.82 mg/L,24.00 mg/L and 22.30 mg/L,respectively.(2)The antioxidant activity of polysaccharide was assessed by its scavenging capacity on the hydroxyl radical,the superoxide anion,the DPPH radical andreducing ability.Polysaccharide extracts from leaf,leaf and root of purslane have high scavenging capacity on the hydroxyl radical,the superoxide anion and the DPPH radical,and clearance rate is 91.40%(the hydroxyl radical),78.01%(the superoxide anion)and 99.36%(the DPPH radical),respectively.Polysaccharide extracts from root of purslane have high reducing ability with 0.80.3.The content of polyphenol substance extracted from whole plant,root,stem,leaf and flower of purslane and its antioxidant activities.(1)The polyphenol of purslane was extracted through ultrasonic wave extraction,then purified by D-101 macroporous resin.The content of polyphenol extracted from different organs of purslane were determined by Folin-Ciocalteu method.The results of polyphenol content showed that: root> leaf,whole plant> flower> stem,leaf and whole plant contain similar amount of polyphenol content.The polyphenol content of root,leaf,whole plant,flower and stem of purslane is 145.81 mg/L,93.85 mg/L,91.83 mg/L,65.00 mg/L and 37.56 mg/L,respectively.(2)The antioxidant activity of polyphenol was assessed by scavenging capacity of the hydroxyl radical,the superoxide anion,the DPPH radical and reducing ability.Polyphenol extracts from stem of purslane have high scavenging capacity on the hydroxyl radical,the superoxide anion and the DPPH radical,and clearance rate is85.07%(the hydroxyl radical),87.81%(the superoxide anion)and 98.67%(the DPPH radical),respectively.Polyphenol extracts from root of purslane have high reducing ability with 1.90.4.Optimization of the ultrasonic wave extraction process of flavonoid from purslane,the content of flavonoid substance extracted from whole plant,root,stem,leaf and flower of purslane and its antioxidant activities.(1)The content of flavonoid were determined by NaNO2-Al(NO3)3 colorimetric method.The effects of ethanol volume fraction,ratio of liquid-to-solid,extraction time and extraction temperature on flavonoid extraction were studied by measuring flavonoid yield in single factor experiments.On the basis of single factor experiment,the ultrasonic wave extraction process of flavonoid from purslane was optimized by response surface methodology.The optimum extraction conditions were 80%,30:1(mL/g),55.40 min and 64.19? for ethanol volume fraction,ratio of liquid-to-solid,extraction time and extraction temperature,respectively.Under these conditions,the predicted and actual yields of flavonoid from purslane were 1.42% and 1.38%,respectively.(2)Flavonoid were extracted by soxhlet extraction method,and then purified by polyamide.The content of flavonoid extracted from different organs of purslane were determined by NaNO2-Al(NO3)3 colorimetric method.The results of flavonoid content showed that: root> leaf,whole plant> flower,stem,leaf and whole plant,flower and stem contain similar amount of flavonoid content.The flavonoid content of root,leaf,whole plant,flower and stem of purslane is 202.62 mg/L,106.19 mg/L,102.91 mg/L,75.25 mg/L and 69.72 mg/L,respectively.(3)The antioxidant activity of flavonoid was assessed by scavenging capacity of the hydroxyl radical,the superoxide anion,the DPPH radical,and reducing ability.Flavonoid extracts from stem,whole plant and whole plant of purslane have high scavenging capacity on the hydroxyl radical,the superoxide anion and the DPPH radical,and clearance rate is 85.61%(the hydroxyl radical),51.70%(the superoxide anion)and 89.38%(the DPPH radical),respectively.Flavonoid extracts from root of purslane have high reducing ability with 1.64.5.Optimization of the ultrasonic wave extraction process of alkaloid from purslane.The content of alkaloid were determined by bromocresol green colorimetric method.The effects of ethanol volume fraction,ratio of liquid-to-solid,extraction time and extraction temperature on alkaloid extraction were studied by measuring alkaloid yield in single factor experiments.On the basis of single factor experiment,the ultrasonic wave extraction process of alkaloid from purslane was obtained by response surface methodology.The optimum extraction conditions were 64.55%,40:1(mL/g),40 min and 64.25? for ethanol volume fraction,ratio of liquid-to-solid,extraction time and extraction temperature,respectively.Under these conditions,the predicted and actual yields of alkaloid from purslane were 1.58% and 1.59%,respectively. |
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