Simultaneous characterization of quaternary alkaloids, 8-oxoprotoberberine alkaloids, and a steroid compound in Coscinium fenestratum by liquid chromatography hybrid ion trap time-of-flight mass spectrometry

Simultaneous characterization of quaternary alkaloids, 8-oxoprotoberberine alkaloids, and a steroid compound in Coscinium fenestratum was successfully performed by liquid chromatography hybrid ion trap time-of-flight mass spectrometry (LC/IT-TOF MS). A total of 32 Compounds, including 2 benzylisoquinoline alkaloids, 3 aporphine alkaloids, 12 quaternary protoberberine alkaloids, 10 8-oxoprotoberberine alkaloids, 3 tetrahydroprotoberberine alkaloids, and a steroid Compound were simultaneously separated and characterized by matching the empirical molecular formulae with those published in literature and the multi-stage mass spectrometry (MS(n)) data obtained using structural information from IT, accurate mass measurement obtained from TOF MS, and HPLC separation. A total of 20 compounds, including 4 novel natural products were identified or tentatively identified for the first time from Coscinium fenestratum. In the positive-ion mode, 8-oxoprotoberberines produced [M + H](+) and [M + Na](+); the fragmentation of 8-oxodihydroprotoberberines produced [M + H-(center dot)CH(3)] (+center dot), [M + H-(center dot)CH(3)-(center dot)CH(3)](+), and [M + H-(center dot)CH(3)-(center dot)CH(3)-CO](+), while 8-oxotetrahydroprotoberberines generated [M + H-(center dot)CH(3)](+center dot), [M + H-(center dot)CH(3)-(center dot)CH(3)](+), [M + H-(center dot)CH(3)-(center dot)H](+), and iminium ions from the cleavage of the protoberberine skeleton. The method can be applied for the analysis of 8-oxoberberine and other alkaloids in Coptis japonica, Phellodendron amurense, and other herbal medicines. (C) 2009 Elsevier B.V. All rights reserved.