Analysis Of Flavonoids Compounds From Four Pyrrosia Species And Their Antioxidant Activity

Pyrrosia lingua is a plant of Pyrrosia in Polypodiaceae,with about100 species in the whole genus,mainly produced in tropical and subtropical Asia.There are 37 species known in China,mainly distributed in warm areas such as Yangtze River Basin,South China and Southwest China.According to Chinese pharmacopoeia,Pyrrosia sheareri（Bak.）Ching,Pyrrosia lingua（Thunb.）Farwell or Pyrrosia petiolosa（Christ）Ching,which are the dry leaves of Polypodiaceae plants,have the functions of diuresis,relieving stranguria,clearing lung-heat and relieving cough,cooling blood and stopping bleeding,and their main medicinal components are flavonoid compounds.However,the systematic research on the specific pharmacological activities of flavonoids in Pyrrosia leaves is still lacking.Objective:Based on UPLC-MS/MS technology,to analyze flavonoids in four Pyrrosia species and compare their antioxidant activities.Methods:Four medicinal plants of Pyrrosia were selected for extraction with different solvents and the best extraction rate was determined.The structure was identified by ultra-high performance liquid chromatography.The antioxidant activity of flavonoids was evaluated by DPPH radical scavenging test and hydroxyl radical scavenging test.Results:The results of the study showed that the total flavonoids in the four Pyrrosia species ethanol extracts were much higher than the total flavonoids in other extraction solvents of Pyrrosia species.The ethanol extract of Pyrrosia petiolosa had the highest total flavonoid content(59.68±0.23 mg·g^-1);The results of the DPPH free radical scavenging experiment showed that the ethanol extracts of the four Pyrrosia species had scavenging ability to DPPH free radicals significantly higher than other solvent extracts,while the chloroform extract had the lowest scavenging ability to DPPH free radicals.Among them,the ethanol extraction of Pyrrosia Petiolosa has the highest scavenging activity on DPPH free radicals,with an IC₅₀value of 0.347±0.02mg·m L^-1;The chloroform extract has the lowest scavenging activity on DPPH free radicals,with an IC ₅₀value of 1.457±0.39 mg·m L-1.The results of determination of hydroxyl radical scavenging ability showed that the ethanol extracts of four Pyrrosia species had significantly stronger scavenging effect on hydroxyl free radicals than the other three solvent extracts.The IC ₅₀(104.39±0.11μg·m L^-1)of scavenging hydroxyl free radical activity of the ethanol extract of Pyrrosia Petiolosa was lower than that of the positive control(143.03±1.26μg·m L^-1),indicating that its scavenging ability was higher than that of the positive control.At the same time,this study used UPLC-MS/MS technology to identify the flavonoids in the four Pyrrosia species ethanol.As a result,a total of 28 compounds were identified,including17 kinds of flavonoids（alcohol）compounds,6 kinds of dihydroflavonoid（alcohol）compounds,1 kind of isoflavones,2 types of flavanols,2 kinds of chromones.13 of which were reported in Pyrrosia for the first time,including Pinocembrin,Pinobanksin,Hesperetin,Myricetin,Isoorientin,5,7-Dihydroxychromone,5,7-Dihydroxy-2-methyl-4H-chromen-4-one,Genistein,Fisetin,Morin,Tricin,Sinensetin,Nobiletin.This study provides a scientific basis for the development of Pyrrosia species medicinal materials and the study of its material basis,and provides a theoretical basis for further exploration of its biological activity in the future.It also lays the foundation for the further functional research and comprehensive utilization of flavonoids for Pyrrosia species.