College of Pharmacy & Kyunghee East-west Pharmaceutical Research Institute, Kyung Hee University, Seoul 130-701, Republic of Korea.
Rapid Commun Mass Spectrom. 2012 Aug 15;26(15):1661-74. doi: 10.1002/rcm.6272.
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).
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.
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.
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.
具有显著治疗效果的生物碱是紫堇属（C.）物种的主要活性成分。C.物种中存在多种生物碱，与植物中不同的生物碱代谢有关，但很少被鉴定。本研究旨在通过液相色谱/电喷雾串联质谱（LC/ESI-MS/MS）鉴定 C.物种中的多种生物碱。
采用 70%甲醇超声提取 C.物种中的几种生物碱，并用 pH 2 和 12 进行萃取。生物碱的分离采用 C18 高效液相色谱（HPLC），通过电喷雾三重四极杆质谱（MS/MS）进行分析。为了进一步确认，采用液相/傅里叶变换离子回旋共振（FTICR）-MS 获得准确的质量数据，并采用气相色谱（GC）/MS 结合三甲基硅烷衍生化法鉴定微量生物碱。
通过 LC/ESI-MS/MS 和 LC/FTICR-MS 成功分离和鉴定了三种不同 C.物种中的 33 种生物碱。根据 MS/MS 光谱模式对各个生物碱的结构进行了赋值。为了进一步确认，通过 LC/FTICR-MS 获得了生物碱的准确质量数据，在 5 ppm 以内，并获得了三甲基硅烷基生物碱的 GC/MS 数据。在所研究的 33 种生物碱中，有 13 种生物碱是首次在研究的 C.物种中报道的。
LC/ESI-MS/MS 技术在获得结构信息方面非常有效，并为多种生物碱提供了诊断离子。基于鉴定出的 33 种生物碱，建议为具有不同地理起源的三种 C.物种选择标记化合物。本研究也可能有助于阐明草药中未知的生物碱。
