Characterization of prenylated xanthones and flavanones by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

Reversed-phase liquid chromatography with atmospheric pressure chemical ion ization mass spectrometry (LC/APCI-MS) in the positive-ion mode was utilize d to analyze crude ether extracts from the root bark of Maclura pomifera, a tree known to have a high content of prenylated xanthones and flavanones. Identification of three xanthones and two flavanones was based on their uni que mass spectra, Under optimum conditions peaks corresponding to the [MH]( +) ion and characteristic fragments for each compound were observed. H-1 NM R data were used to confirm the identities of two xanthones that had the sa me molecular mass and similar fragmentation patterns. Fragmentation of the analytes was achieved by application of an electrostatic potential at the e ntrance of the single quadrupole mass spectrometer. The optimum voltage for fragmentation was found to be related to the class of compounds analyzed a nd, within each class, to be dependent on the structure of the prenyl moiet y. Collision-induced pathways consistent with precedent literature describi ng the MS characterization of similar compounds and with the observed fragm entation patterns are tentatively proposed. Copyright (C) 2000 John Wiley & Sons, Ltd.