| Ulmus pumila L.,also known as Ulmus manshurica and Ulmus pumila var.microphylla,belongs to Ulmus of Ulmaceae in taxonomy,and is one of the characteristic native trees in Henan Province,with high medicinal and edible value.Ulmus pumila are rich in active ingredients such as flavonoids,phenolic acids,polysaccharides,terpenes,and fatty acids,which have antioxidant,antibacterial,anti-inflammatory,anticancer,and liver protective effects.At present,the research on Ulmus pumila mainly focused on the extraction,separation and identification of the natural components of Ulmus pumila bark,there are few researches on antioxidant activity and inhibition of α-glucosidase in different parts of Ulmus pumila.On this basis,this study takes the leaf and bark and fruit of Ulmus pumila as the experimental object,and determines the content of its main chemical components through spectrophotometry.The content of phenolic substances and monosaccharides are measured using high performance liquid chromatography-mass spectrometry(HPLC-MS)method,and further explore the antioxidant activity of the water extracts and its inhibitory effect on αglucosidase,as well as the relationship between active components and biological activities,to provide a certain theoretical basis for the rational development and utilization of Ulmus pumila resources.The results of the study are as follows:(1)The water extract and powder of the leaves(leaves in March,June,and October)and bark and fruits of Ulmus pumila were characterized by Ultraviolet visible spectrum(UVVis)and Fourier transform infrared spectroscopy(FT-IR),and the results showed that the characteristic absorption peaks of flavonoids,phenols,and sugars appeared in both UV Vis and FT-IR spectra,and have certain similarities;At the same time,the content of total flavonoids,total phenols,and polysaccharides were determined using aluminum nitrate colorimetry,folin-Ciocalteu method,and phenol sulfuric acid method,respectively.The results showed that the content of total flavonoids,total phenols,and polysaccharides in the bark was higher than that in leaves and fruits,indicating that the bark may have high development and utilization value.(2)The contents of six phenolic substances(catechin,epicatechin,quercetin,rutin,chlorogenic acid,ferulic acid)in the leaves and bark and fruits of Ulmus pumila were determined by high performance liquid chromatography-mass spectrometry(HPLC-MS).Through the established detection method,within a certain concentration range,the linear relationship of the six phenolic substances was good,and the precision,repeatability,and spiked recovery rate all meet the analysis requirements.The results showed that six phenolic substances were detected in the leaves and bark and fruits of Ulmus pumila,among which chlorogenic acid was more abundant in Ulmuspumila,with the content was between 1.44 and 13.76 mg/g;followed by the content of epicatechin was between 363.60 and 8476.69 μg/g;the content of catechin was between 44.53 and 8211.70 μg/g;the content of rutin was between 11.03 and 1198.70 μg/g;the content of ferulic acid was between 57.34 and 729.23 μg/g;the content of quercetin was the lowest,was between 29.16 and 68.85 μg/g.The total content of six phenolic substances in each sample was between 2.40 and 18.35 mg/g,the contents of six phenolic substances in bark were higher than those in leaves and fruits,and the catechin and epicatechin content is significantly higher than the other two parts.(3)The content of four monosaccharides in Ulmus pumila leaves and bark and fruits was determined by high performance liquid chromatography-mass spectrometry(HPLC-MS),within the concentration range of 200～5000 mg/L,the linear relationship of rhamnose,xylose,galactose,and mannitol is good,and the precision,repeatability,stability,and spiked recovery rate meet the analysis requirements.Through the established HPLC-MS method,the content of galactose in Ulmus pumila leaves and bark and fruits was between 36.84 and 313.21 mg/g;the xylose content was between 22.54 and 128.74 mg/g;the content of rhamnose was between 21.47 and 81.26 mg/g;the content of mannitol was between 18.43 and 67.63 mg/g.The total content of four monosaccharides in each sample was between 116.12 and 590.84 mg/g,and the overall performance is that the bark is higher than the leaves and fruits,which is consistent with the determination results of phenolic substances,indicating that the content of phenolic and polysaccharide substances in the bark of Ulmus pumila is rich.(4)The antioxidant activities of water extracts of Ulmus pumila leaves and bark and fruits were detected by DPPH free radical scavenging method,ABTS free radical scavenging method,and FRAP total reducing power method;use the pNPG method to detected the inhibitory effect on α-glucosidase,exploring the type of inhibition combined with inhibition kinetics of enzyme catalysis.The results showed that the antioxidant activity of the bark water extracts and its inhibitory effect on α-glucosidase was strong,in three different stages of leaves,the antioxidant activity of the water extract from June leaves is stronger,while the water extract from October leaves has a stronger effect on inhibitory effect on α-glucosidas.In addition,the inhibitory effect on α-glucosidas of water extract of Ulmus pumila leaves and bark and fruits can be reversed,among which the inhibition types of June leaves,bark,and fruits are mixed type I inhibition,while the inhibition types of March and October leaves are competitive and non competitive inhibition,respectively.The different inhibition types indicate that there may be differences in the binding sites with the enzyme.The analysis results of the correlation between components and activity show that the antioxidant activity and inhibition of α-glucosidase of Ulmus pumila leaves and bark and fruits is correlated to varying degrees with the phenolic and polysaccharide substances it contains,which may be the main functional components for the activity of Ulmus pumila.The catechin and epicatechin may be the main functional components of Ulmus pumila bark exert biological activity.Ulmus pumila with antioxidant activity and inhibition of α-glucosidase enzymes,are the result of a variety of active ingredient collaborative involvement. |
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