| ObjectiveLycium ruthenicum Murray?LM?has plenty of nutritional components and biologically active ingredients,such as phenolic acids,flavones,alkaloids,anthocyanins and so on.And its edible and medicinal value has been widely concerned in recent years.This study foucued on the analysis of mineral elements,amino acids and polyphenols from LM.And then,the antioxidant capacity of the LM extract and its inhibitory effect on ?-glucosidase activity were investigated.The results of this study will provide a theoretical basis for the further development and utilization of LM?Methods1.Composition analysis of mineral elements,amino acids and phytochemicals in LMFirstly,mineral elements composition analysis of LM were performed by microwave digestion-atomic absorption spectrometry.The phosphorus-molybdenum blue colorimetric method was used to detect the content of phosphorus in sample.After that,the amino acids in the sample were analyzed using an amino acid analyzer.In addition,using pure water and 60%?V/V?ethanol as the solvent,the active ingredients in the sample were extracted with the assistance of ultrasound,at the same time,the water extract and ethanol extract of LM were labeled as WEM and EEM,respectively.Finally,the total content of polyphenols and flavones in the extracts were examined by visible spectrophotometry,while the contents of phenolic acids,flavones,alkaloid and anthocyanin in the extracts were determined by high performance liquid chromatography.2.Analysis of antioxidant activity of LM extractThe antioxidant activities of LM extract were studied by four methods:·OH scavenging activity,DPPH*scavenging activity,ABTS+· scavenging activity,and reduction power.The anti-oxidation experiments were performed with the spectrophotometric method.The water-soluble vitamin E?Trolox?was used as positive control.3.Inhibition of LM extract against ?-glucosidase activityUsing 4-nitrophenyl-?-D-glucopyranoside as substrate,the content of enzymatic reaction products p-nitrophenol was determined by spectrophotometry.On this basis,the inhibitory effect of LM extract against ?-glucosidase activity was investigated.Acarbose was used as positive control.Results1.Composition and content of mineral elements,amino acids and polyphenols in LMThe results of the mineral elements in the sample were as follows:the content of iron was the highest in trace elements,147.26±2.44 ?g/g;the content of cobalt was the lowest,0.11±0.04 ?g/g.The value of zinc,copper,manganese,nickel,chromium was 26.93±1.48,13.84±1.58,8.57±0.22,265±0.67,1.95±0.28 ?g/g,respectively.Lead is a toxic element,its value was 0.13±0.01 ?g/g,which complied with food hygiene standards.The content of potassium.calcium,sodium,phosphorus,and magnesium in macro elements was 21.77±1.04,3.52±0.54,3.41 ±0.27.2.59±0.22,1.61 ±0.04 mg/g,respectively.The results of the amino acids in LM were as follows:16 kinds of amino acids were detected in the sample.including 7 kinds of nutrient-essential amino acids?EAA?,namely threonine?Thr?.valine?Val?,methionine?Met?,isoleucine?Ile?,leucine?Leu?.phenylalanine?Phe?and lysine?Lys?,the contents of them were 0.31.0.33,0.09.0.24,0.37,0.42,0.36 g/100 g,respectively.Among these amino acids,the amino acid with the highest content was glutamic acid?Glu?,1.12 g/100 g;the content of methionine?Met?was the lowest at 0.09 g/100 g.The total amino acids?TAA?was 6.93 g/100 g.and EAA/TAA was 29.29%.Glu and aspartic acid were umami amino acids,and its content was accounting for 31.31%of TAA.Asp.Glu.Gly,Met,Leu.Tyr,Phe.Lys.Arg belong to medicinal amino acids,and its content was accounting for 66.09%of TAA.The results of phenolic acid,flavonoids,alkaloids and anthocyanins in the LM extract were as follows:the contents of total polyphenols and total flavonoids in WEM were 22.07±0.39 mg/g and 15.70±0.36 mg/g.And the contents of total polyphenols and total flavonoids in EEM were 23.51±0.05,20.62±1.20 mg/g,respectively.The contents of p-coumaric acid,rutin and colchicine in WEM were 400.69±50.16,354.64±35.43,69.95±7.39 mg/kg,respectively.While,the contents of p-coumaric acid,rutin and colchicine in EEM were 229.30±26.45,241.01±37.23,104.10±20.94 mg/kg,respectively.The contents of delphinidin and petunia in WEM were 45.51±8.86 mg/kg and 31.99±8.07 mg/kg,and the contents of delphidin and petunia in EEM were 106.98±26.88 mg/kg and 66.90±2.59 mg/kg,respectively.2.Antioxidant ability of LM extractThe WEM and EEM revealed certain antioxidant activity,and the antioxidant activity increased with the increase of the extract concentration.The half inhibitory concentration?IC50?of WEM to scavenge·OH,DPPH·,ABTS+· was 354.66±4.65,77.31±1.49,99.48±5.21 ?g/mL,respectively.The IC50 of EEM to scavenge·OH,DPPH·,ABTS+· was 888.40±44.53,67.79±6.01,75.84±1.56 ?g/mL,respectively.They also exhibited effectively reduction power.Compared with the antioxidant capacity of Trolox,the antioxidant capacity of LM extract was relatively weak.3.Inhibitory capacity of LM extract against ?-glucosidase activityThe LM extract exhibited excellent inhibitory capacity against ?-glucosidase activity,and the inhibitory capacity increased with the increase of the extract concentration.The IC50 of WEM,EEM and the positive control?acarbose?to inhibit on ?-glucosidase activity was 1272.27±42.40,1176.24± 17.75 ?g/mL,0.14±0.00 ng/mL,respectively.Both WEM and EEM showed reversible inhibition on?-glucosidase.The enzyme kinetic analysis revealed that the types of inhibition of WEM and EEM on ?-glucosidase were mixed inhibition,and the inhibition constants Ki were 1.42,1.01 mg/mL,Kis were 3.64,1.74 mg/mL,respectively.Conclusions1.LM was rich in mineral elements,essential amino acids and other nutritional ingredients,which are closely related to health.In addition,it contained p-coumarate,rutin colchicine,delphinium,petunia and other bioactive substances.2.WEM and EEM of LM had good antioxidant activity and excellent inhibitory capacity against ?-glucosidase activity.3.The phenolic acids,flavonoids,alkaloids and anthocyanins in the LM extract may be the material basis for its antioxidant and inhibitory enzyme activities... |
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