| Medicine food homology plants,rich in phenolic acids and flavonoids,are high-quality materials for functional food with hypouricemic potential.Scientific compatibility of different medicine food homology plants not only can improve bioaccessibilities and bioavailabilities of chemical components in plants,but also have a synergistic effect on activity.At present,food ingredients of plant extracts with hypouricemic effect are usually single plant extracts,moreover,the basic theory of compound plant extracts processing is relatively weak.In the present study,xanthine oxidase(XO)inhibitory mechanisms and interaction of two galangal flavonoids were explored.The quality control standards for single extract of galangal with strong XO inhibitory(XOI)activity were established.The similarities and differences in the compound composition of different batches of galangal,lotus leaf,Chrysanthemum morifolium cv.‘Boju’,mint,perilla leaf and elsholtzia were analyzed to clarify characteristic compounds in each plant.The influence of characteristic compounds on bioaccessibilities of galangal flavonoids was evaluated to screen out suitable plants for compatibility with galangal.The chemical compositions,XOI activities and bioaccessibilities of galangal flavonoids of compound extracts of galangal were analyzed.Finally,the best extract method and plant compound were determined,and the directional preparation of compound plant extract with strong XOI activity and high bioaccessibilities of galangal flavonoids was realized.The aim of the present study is to provide theoretical and methodological guidance for the directional preparation of compound plant extract food ingredients with hypouricemic potential using galangal as main ingredient and to provide new ideas for the development of functional foods derived from medicine food homology plants.The main results were listed as follows:(1)The inhibition mechanisms of kaempferide and galangin on XO were comparatively investigated by kinetics analysis of XO inhibition,fluorescence quenching and in silico molecular docking.The results showed that kaempferide and galangin,binding to XO driven by hydrophobic interactions and hydrogen bonds,were competitive inhibitors of XO.The methoxy group at C-4′ increased hydrogen bond acceptor/donor number of galangin,facilitated the formation of 3 more hydrogen bonds with XO,improved binding affinity for XO,and changed targeted amino acid residues(Glu802,Arg880)of molybdopterin domain,enhancing XOI activity of galangin.The interaction of kaempferide and galangin enhanced their binding affinities for XO,showing synergistic inhibition on XO at optimal molar ratio 1:4.The contents and composition molar ratio(1:4)of kaempferide and galangin should be regarded as quality control standards for single extract of galangal with strong XOI activity.(2)A total of 34 small molecule compounds including 29 phenolic compounds were identified in 6-7 batches of galangal,lotus leaf,Chrysanthemum morifolium cv.‘Boju’,mint,perilla leaf and elsholtzia.The contents of polyphenols in galangal,lotus leaf,Chrysanthemum morifolium cv.‘Boju’,mint,perilla leaf and elsholtzia were 1258-1429,1754-2400,2773-4410,189-821,252-2747,440-1414 mg/100 g plant.The characteristic compounds in galangal were galangin,diphenylheptane A and kaempferide;The characteristic compounds in lotus leaf were quercetin-3-O-glucuronide,quercetin-3-O-glucoside and nuciferine;The characteristic compounds in Chrysanthemum morifolium cv.‘Boju’ were 3,5-dicaffeoylquinic acid,chlorogenic acid and 4,5-dicaffeoylquinic acid.Rosmarinic acid,luteolin-7-O-glucuronide and apigenin-7-O-glucuronide were characteristic compounds in perilla leaf and elsholtzia,and their contents in perilla leaf were higher.Diosmetin,acacetin,luteolin,apigenin in Chrysanthemum morifolium cv.‘Boju’ and kaempferide and galangin in galangal exhibited the strongest XOI activities.Based on Caco-2 monolayer cells model,when galangin and kaempferide were co-transported at a molar ratio of 3:1,the transport amounts of galangin and kaempferide were respectively 5.2 times and 2.8 times that of the transport alone.On the basis of co-transportation of galangin and kaempferide,the transport amounts of galangin and kaempferide were enhanced by 10.37-20.88% and 18.72-40.18% respectively by adding diphenylheptane A,quercetin-3-O-glucoside,chlorogenic acid,apigenin and luteolin.The seventh batch of galangal,the seventh batch of lotus leaves and the sixth batch of Chrysanthemum morifolium cv.‘Boju’ was the best compatibility of plant.(3)Eighteen compound extracts of galangal were prepared by ultrasonic-assisted ethanol extraction and ethanol reflux extraction.XOI activities and contents of 12 characteristic compounds of compound extracts of galangal were analyzed by UPLC-MS.The results showed that the extraction rate of characteristic compounds and dissolution rate of XOI active compounds were higher by ethanol reflux extraction,which was the best way to prepare compound extracts of galangal.The XOI values of compound extracts of galangal were from43.31 to 62.96 μmol AE/g extract.The galangin extraction rates were 197.98-661.94 mg/100 g plant,while the kaempferide extraction rates were 67.37-201.22 mg/100 g plant.The bioaccessibilities of galangal flavonoids were evaluated using Caco-2 cells model.The compatibility of galangin with lotus leaf alone significantly reduced transport rates of galangin and kaempferide by 23.00%/21.38% and 10.83%/15.79%,respectively.The compatibility of galangin with Chrysanthemum morifolium cv.‘Boju’ alone significantly increased transport rate of galangin by 11.90% and had no effect on transport of kaempferide.When galangal,lotus leaf,and Chrysanthemum morifolium cv.‘Boju’ are compounded in a mass ratio of 5:1.5:3.5,the XOI value of compound extract was 52.82 μmol AE/g extract.The transport rates of galangin and kaempferide in Caco-2 cells were increased by 21.17% and 34.92% respectively compared to that in singal extract of galangal.Therefore,galangal,lotus leaf,and Chrysanthemum morifolium cv.‘Boju’ compounded in a mass ratio of 5:1.5:3.5 was the best plant compound.Using the best plant compound and ethanol reflux extraction could realize the directional preparation of the compound extract food ingredient with strong XOI activity and high bioaccessibilities of galangal flavonoids. |
