| The culture of "homology of medicine and food" is an excellent traditional culture with a long history in China.Recently,medicinal and edible homologous ingredients have attracted the attention of scholars in China and abroad.Glycyrrhiza uralensis Fisch(G.uralensis),Lophatherum gracile(L.gracile),Houttuynia cordata Thunb(H.cordata)all belong to the category of clearing away heat and relieving exterior syndrome in traditional Chinese medicine,which contain a variety of bioactive substances,enjoying wide applications in food processing and drug research.Nevertheless,the current comparative research on its composition and biological activities of these three kinds of medicinal and edible homologous ingredients is less.And the extraction methods mostly uses organic solvents like ethanol or ethyl acetate generally have potential safety problems such as chemical pollution.The extraction solvent of ultrasonic-assisted water extraction is pure water,which has no chemical pollution,and can be directly applied to food with wider application range and higher safety.Meanwhile,ultrasonic cavitation can also shorten the extraction time and improve the extraction rate.As food grade raw materials,G.uralensis,L.graciland and H.cordata are mainly processed by boiling.As a result,relevant aqueous extract components may be closely related to exertion of its activity.In this study,ultrasonic assisted extraction of aqueous extracts from G.uralensis,L.graciland H.cordata was adopted in this study.Liquid chromatography-mass spectrometry(LC-MS)was used to analyze the composition and content information of the aqueous extracts,and a varity of biological activities such as antioxidant and antiviral effects were investigated,which provides theoretical basis for the research and development of functional food and tonic diet related to the three ingredients,offering reasonable nutritional dietary suggestions.Specific research results are drawn as follows:(1)Firstly,aqueous extracts of the three ingredients were collected by ultrasonic-assisted hot aqueous extraction,and components and contents of aqueous extracts of the three ingredients were qualitatively and quantitatively detected by LC-MS.The qualitative results showed that the main components of G.uralensis aqueous extract were flavonoids,saponins,polysaccharides and organic acids.The main components of L.gracile aqueous extract were organic acids,polysaccharides,coumarins,phenols,etc.The main components of H.Cordata aqueous extract included alkaloids,coumarins,organic acids and flavonoids.The three aqueous extracts all contained organic acids and polysaccharides,but their types and contents were different,suggesting that the three aqueous extracts might have certain antibacterial and antioxidant effects.The aqueous extract of L.gracile contained the most types of polysaccharides,including trehalose,mannitol,stachyose and maltose,with the relative percentage content of 4.14%.The aqueous extracts of G.uralensis and L.gracile contained a variety of organic acids,including linoleic acid and malic acid,and the relative percentage contents were also high,13.07%and 21.31%,respectively.The organic acid of the aqueous extract of H.Cordata was mainly nicotinic acid,and the relative percentage content was low,indicating that the aqueous extracts of G.uralensis and L.gracile might have high antibacterial and antioxidant activities.Flavonoids are components contained in the aqueous extracts of G.uralensis and H.Cordata The flavonoids in the aqueous extracts of G.uralensis mainly include liquiritigenin,naringenin,isoliquiritigenin,and formononetin.The relative contents of liquiritigenin and isoliquiritigenin were higher,reaching 28.36%and 17.35%,respectively.The flavonoid in H.Cordata was mainly glycitein,and the relative percentage content was lower,0.35%.In addition,with a small amount,coumarins and phenolic acids were important components of the aqueous extracts G.uralensis and H.Cordata.In addition,the aqueous extract of H.cordata contained a variety of alkaloids,including trigonelline,betaine and stachyine nicotinate,indicating that it might have certain antitumor and antioxidant activities.The results showed that the three aqueous extracts were rich in bioactive substances,displaying potential biological activities.(2)Antibacterial activity detection of aqueous extracts from G.uralensis,L.gracil and H.cordata.The Oxford Cup method was used to investigate the antibacterial activity of aqueous extracts from G.uralensis,L.graciland and H.cordata against common foodborne pathogens(Escherichia coli,Staphylococcus aureus and Salmonella).The antibacterial activity was indicated by the diameter of inhibition zone.It was found that G.uralensis aqueous extract exhibited the strongest antibacterial activity against Staphylococcus aureus(11.3±0.1 mm)and Escherichia coli(13.2 ± 0.1 mm),with certain antibacterial activity against Salmonella(8.0±0.1 mm).The aqueous extract exhibited relatively strong antibacterial activity against Staphylococcus aureus(11.1 ± 0.2 mm),with strong activity against Escherichia coli(8.9±0.1 mm)and Salmonella(8.0±0.1 mm).H.Cordata aqueous extract exhibited stronger antibacterial activity against Staphylococcus aureus(10.3±0.1 mm)and Escherichia coli(12.2±0.1 mm)than against Salmonella(8.0±0.1 mm).The results showed that the three aqueous extracts exhibited certain antibacterial activity against Staphylococcus aureus,Escherichia coli and salmonella,with greater inhibitory effect on Staphylococcus aureus and Escherichia coli than on Salmonella,which could be applied to the research and development of marinated meat,egg-bearing milk,seafood and other food or medicinal diet.(3)The scavenging activities of DPPH radical,ABTS radical and superoxide anion radical were determined for each extract to investigate the antioxidant activities of aqueous extracts from G.uralensis,L.graciland and H.cordata.The results showed that in the concentration range of 62.5～1000 mg/mL,the aqueous extracts from the three ingredients presented certain scavenging activities against DPPH radical,O2·-radical and ABTS radical,with scavenging rates positively correlated with the concentration.When the aqueous extract concentration increased from 62.5 mg/mL to 1000 mg/mL,the scavenging rate of G.uralensis aqueous extract against superoxide anion radical increased from 7.52%to 21.06%,and the scavenging rate of L.gracile aqueous extract against superoxide anion radical increased from 8.21%to 26.13%,while the scavenging rate of H.Cordata aqueous extract against superoxide anion radical increased from 6.43%to 18.22%.It was found that the aqueous extracts of the three ingredients all exhibited certain antioxidant activity,which may be related to polysaccharide and flavonoids in the aqueous extracts,providing material basis for preventing various diseases and maintaining body health.(4)The effect of aqueous extracts from G.uralensis,L.graciland and H.cordata on bacteriophage infection of Enterobacter hormaechei was investigated by inverted double AGAR plate method.The results showed that at 2 h and 4 h,the three aqueous extracts had obvious effects on bacteriophage-infected bacteria,especially at 4 h when the number of bacteriophage plaque was significantly different from that of the control group(p<0.05).The action intensity was ranked in descending order as that of G.uralensis aqueous extract>H.Cordata aqueous extract>L.gracile aqueous extract.After 6 h,the bacteriophage titer tended to stabilize with little variation.The results showed that the three aqueous extracts had certain inhibitory effect on bacteriophage infection,especially before the proliferation of the three aqueous extracts,proving that the three aqueous extracts had certain antiviral effect,and supplementation of the three food ingredients before the massive infection of the virus can yield therapeutic effect,achieving the "disease prevention" effect in traditional Chinese medicine.In this study,a variety of active substances were detected in the aqueous extracts of the three medicinal and edible homologous ingredients,namely G.uralensis,L.graciland and H.cordata.It was confirmed that the aqueous extracts from the three ingredients had various biological activities,such as antibacterial,antioxidant and antiviral activities,which provided theoretical basis for the research and development of functional food,health food,daily medicinal diet,new food preservative and edible food preservative film. |
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