Characterization of Berberine C8-Position Proton Dissociation
To study the proton dissociation properties and structural characteristics of berberine cation in alkaline environment,berberine was dissolved to D2O and catalyzed by triethylamine for deuterating reaction.The reaction products were detected and identified by NMR and LC-MS.The electronic structures of berberine were established and the electrostatic potential distribution,and the free energy of berberine were calculated out by Gaussian16.The results showed that the reaction product in the al-kaline environment of triethylamine was recognized as the 8-deuterium berberine.The distribution of the electrostatic potential through the quantum chemical model of berberine showed that the maximum value point was located at C8,and the maximum value was+100.04 kcal/mol.By comparing the re-sults of proton dissociation energies of each hydrogen atoms on the aryl ring of berberine,it was found that the lowest proton dissociation energy was at the C8 position of berberine.The combination of ex-perimental results and computational chemistry data indicate that the proton at the C8 position of ber-berine has a certain acidic property,which can be ionized under alkaline environment.The C8 position is susceptible to be attacked and reacted by nucleophilic reagents,which may provide reference for the structural modification of the C8 position of berberine.
berberinedeuteriumquantum chemical computingelectrostatic potential on molecular surfaceproton dissociation energy
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