Identification of structurally diverse alkaloids in Corydalis species by liquid chromatography/electrospray ionization tandem mass spectrometry.
BACKGROUND
Alkaloids with significant therapeutic effects are the main active constituents of Corydalis (C.) species. There are several kinds of alkaloids in C. species associated with diverse alkaloid metabolism in plants, but they are rarely identified. This study aimed to identify diverse alkaloids in C. species by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS).


METHODS
Several types of alkaloids were extracted from C. species using ultrasonication with 70% CH(3)OH, and the extract was partitioned at pH 2 and 12. Separation of alkaloids was achieved by C18 high-performance liquid chromatography (HPLC), and MS/MS analysis was conducted by electrospray ionization triple-quadrupole mass spectrometry. For further confirmation, LC/Fourier transform ion cyclotron resonance (FTICR)-MS was used to obtain accurate mass data and gas chromatography (GC)/MS combined with trimethylsilyl derivatization was applied for identification of the minor alkaloids.


RESULTS
Thirty-three alkaloids among three different C. species were successfully separated and identified by LC/ESI-MS/MS and LC/FTICR-MS. Structural assignment of individual alkaloids was performed according to MS/MS spectral patterns. For further confirmation, accurate mass data of alkaloids by LC/FTICR-MS were obtained within 5 ppm and the GC/MS data for the trimethylsilyl alkaloids were also obtained. Among 33 alkaloids identified from this study, 13 alkaloids were reported for the first time in the investigated C. species.


CONCLUSIONS
The LC/ESI-MS/MS technique was effective in obtaining structural information and yielded diagnostic ions for diverse alkaloids. Based on the identified 33 alkaloids, marker compounds were suggested for the three C. species with different geographic origins. This study may also be useful for elucidating unknown alkaloids in herbal medicines.
College of Pharmacy & Kyunghee East-west Pharmaceutical Research Institute, Kyung Hee University, Seoul 130-701, Republic of Korea.
Eun-Kyung
EK
Jeong
Sun Young
SY
Lee
Se Mi
SM
Yu
Na Hyun
NH
Park
Hyun-Seok
HS
Lee
Yong-Hyeon
YH
Yim
Geum-Sook
GS
Hwang
Chaejoon
C
Cheong
Jee H
JH
Jung
Jongki
J
Hong
D000470:Alkaloids / Q000737:chemistry* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D031311:Corydalis / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
D000470:Alkaloids; D010936:Plant Extracts