橡胶草化学成分鉴定及质谱裂解规律研究

Identification of Chemical Components in Taraxacum kok-saghyz Rodin and Investigation of Mass Spectrometric Fragmentation Pathways

  • 摘要: 本研究采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱(UHPLC-Q/Orbitrap HRMS)法鉴定蒲公英属中草药橡胶草的化学成分。采用超声/微波辅助萃取技术提取橡胶草样品成分,通过ACQUITY UHPLC BEH C18色谱柱(150 mm×2.1 mm,1.7 µm)进行液相色谱分离。采用电喷雾电离源正、负离子模式电离,四极杆/静电场轨道阱高分辨质谱仪检测数据,基于全扫描-数据依赖型二级质谱扫描(Full MS/dd-MS2)模式采集样品数据。原始数据采用Xcalibur 4.1软件进行色谱峰对齐和提取,将获得的前体离子和碎片离子的精确质量数信息与赛默飞中药成分高分辨质谱数据库(OTCML)、自建数据库和GNPS(Global Natural Products Social Molecular Networking)在线网站的数据库信息进行匹配,共鉴定出黄酮类、生物碱类、萜类、酚类、氨基酸类、苯丙素类、有机酸类、核苷酸类及其他类共94种化合物,并对部分典型化合物的质谱裂解规律进行解析,为阐明橡胶草非橡胶化学成分的药理作用提供科学依据。

     

    Abstract: Taraxacum kok-saghyz Rodin, a perennial herbaceous plant of the genus Taraxacum (Asteraceae), has widely distributed in Europe, the Americas, and northwestern and northeastern China. However, the specific bioactive compounds responsible for its pharmacological effects remain uncharacterized, necessitating experimental validation to establish a theoretical foundation. This study systematically characterized the chemical constituents of Taraxacum kok-saghyz Rodin, a medicinal plant of the dandelion genus, using ultra-high-performance liquid chromatography coupled with quadrupole/Orbitrap high-resolution mass spectrometry (UHPLC-Q/Orbitrap HRMS). The sample pretreatment process involved optimizing solvent selection. One gram of dried rubber dandelion root or leaf powder was mixed with methanol and subjected to ultrasonic/microwave-assisted extraction (microwave power of 450 W, ultrasonic power of 550 W, temperature of 50 ℃, and extraction time of 30 min), followed by chromatographic separation on an ACQUITY UHPLC BEH C18 column (150 mm×2.1 mm, 1.7 µm) at 40 ℃, with an injection volume of 3 μL per run. The mobile phase consisted of water containing 0.1% formic acid and 2.5 mmol/L ammonium formate (A) and acetonitrile (B) at a flow rate of 0.3 mL/min. Electrospray ionization (ESI) was employed for ionization. Full scan/data-dependent tandem mass spectrometry (MS/MS) scan (Full MS/dd-MS2) acquisition mode ensured comprehensive coverage of precursor and fragment ions, with a scan range of m/z 80-1 200. Full scan resolution was set at 60 000, while dd-MS2 scan resolution reached 15 000. The raw data were processed using Xcalibur 4.1 software for chromatographic peak alignment and extraction. Accurate mass information for precursor and fragment ions was meticulously compared with three databases of the Orbitrap Traditional Chinese Medicine Library (OTCML), a self-curated database, and the Global Natural Products Social Molecular Networking online platform. A total of 94 compounds were identified, encompassing 4 flavonoids, 5 alkaloids, 11 terpenoids, 8 phenolics, 6 amino acids, 13 phenylpropanoids, 10 organic acids, 4 nucleotides, and 33 other types of compounds. To ensure the accuracy of compound identification, reference standards (chlorogenic acid, caffeic acid, p-coumaric acid, 7-hydroxycoumarin, and ferulic acid) were subjected to mass spectrometric characterization, effectively eliminating false-positive interferences. This study revealed that amino acids and phenylpropanoids exhibit higher mass spectrometric responses, whereas alkaloids show weaker responses. By analyzing the fragmentation pathways of representative compounds, the structural characteristics were elucidated, providing a scientific basis for deciphering the pharmacodynamic material foundation of non-latex components in Taraxacum kok-saghyz Rodin. This study also offers data support for exploring the high-value utilization of non-rubber components in Taraxacum kok-saghyz Rodin. Taraxacum kok-saghyz Rodin exhibits a complex matrix composition and a diverse array of natural constituents. Future research prospects should integrate nuclear magnetic resonance (NMR) spectroscopy with artificial intelligence (AI)-driven pattern recognition methodologies to enhance data accuracy and improve the comprehensiveness of phytochemical characterization.

     

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