Chemical Composition Analysis of Platycladi Cacumen Before and After Being Carbonized Based on Identification by UHPLC-QTOF-MS/MS / 中国实验方剂学杂志

ABSTRACT

Objective:To identify the chemical constituents of Platycladi Cacumen<italic> </italic>before and after being carbonized. Method:Chemical constituents in 3 batches of Platycladi Cacumen and its carbonized products<italic> </italic>were identified and compared by ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry （UHPLC-QTOF-MS/MS）. Chromatographic separation was performed on an ACQUITY UPLC BEH C₁₈ column （2.1 mm×100 mm， 1.7 μm） with 0.1% formic acid aqueous solution （A）- acetonitrile （B） as mobile phase for gradient elution （0-3.5 min， 5%-15%B； 3.5-6 min， 15%-30%B； 6-6.5 min， 30%B； 6.5-12 min， 30%-70%B； 12-12.5 min， 70%B； 12.5-18 min， 70%-100%B； 18-22 min， 100%B）. The flow rate was 0.4 mL·min^-1 and the injection volume was 5 μL. Mass spectrometry was performed by an electrospray ionization， and the primary and secondary mass spectrometry data were collected with the full scan mode of positive and negative ions， the peaks containing MS/MS data were identified by self-established secondary mass spectrometry database and corresponding fragmentation law matching method. Result:A total of 77 and 76 substances with the same change trend were identified under positive and negative ion modes. After being<italic> </italic>carbonized， the disappeared components of Platycladi Cacumen were mainly amino acids， ketone aldehydes and other volatile components. Among newly produced components， there were 6 kinds of flavonoid aglycones （rhamnetin， 6，7，3'-trihydroxyflavone， 3，6，3'-trihydroxyflavone， 4'-hydroxy-2'-methyl-3，4，5-trimethoxychalcone， herbacetin and 3'，5'-dimethoxy-3，5，7，4'-tetrahydroxyflavone）， 3 kinds of coumarins （7-hydroxycoumarin， 7，8-dihydroxycoumarin and 8-acetyl-7-hydroxycoum-arin） and 3 kinds of benzoic acids （3-methylcatechol， pyrocatechol and chromone-3-carboxylic acid）. There were a total of 40 flavonoids （quercitrin， quercetin， kaempferol， etc.） among these identified chemical constituents. Conclusion:There are significant quantitative and qualitative changes in the chemical compositions of Platycladi Cacumen after being carbonized. The flavonoids， the identified main active ingredients， can provide data reference for further study on the material basis of efficacy changes of Platycladi Cacumen<italic> </italic>before and after being carbonized.