Characterization and Identification of the Ent-Kaurane Diterpenoids in Isodonis Excisoidis Herba Using...

Area of Science:

• Natural Product Chemistry
• Pharmacognosy
• Analytical Chemistry

Background:

• Isodonis Excisoidis Herba (IEH) is a newly discovered herbal medicine with therapeutic applications in esophageal cancer, chronic pharyngitis, and hepatitis.
• Ent-kaurane diterpenoids are the primary active constituents of IEH.
• A systematic investigation into the chemical profile and fragmentation patterns of these ent-kaurane diterpenoids is currently lacking.

Purpose of the Study:

• To investigate the fragmentation behaviors of different types of ent-kaurane diterpenoids present in IEH.
• To establish systematic fragmentation pathways for characterizing these compounds using UHPLC-LTQ-Orbitrap-MS.
• To identify and tentatively characterize the ent-kaurane diterpenoids within IEH.

Main Methods:

• Ultra-High-Performance Liquid Chromatography coupled with a Linear Trap Quadrupole-Orbitrap Mass Spectrometer (UHPLC-LTQ-Orbitrap-MS) was employed.
• Analysis focused on the fragmentation patterns of three distinct classes of ent-kaurane diterpenoids: bridgehead-unsubstituted 7,20-epoxy-ent-kauranes, bridgehead-substituted 7,20-epoxy-ent-kauranes, and 7,20-non-epoxy-kaurane diterpenoids.
• Accurate mass measurements of precursor and fragment ions were utilized for compound identification.

Main Results:

• Distinct fragmentation pathways were elucidated for each of the three types of ent-kaurane diterpenoids based on characteristic ion losses.
• A total of 94 ent-kaurane diterpenoids were identified or tentatively characterized in IEH.
• This comprehensive analysis includes the discovery of 48 potentially new ent-kaurane diterpenoid compounds.

Conclusions:

• The study provides a systematic approach to the chemical profiling of ent-kaurane diterpenoids in IEH using advanced mass spectrometry.
• The identified compounds, particularly the novel ones, contribute significantly to the understanding of IEH's chemical diversity.
• These findings lay the groundwork for further research into the pharmacological activities and potential therapeutic applications of IEH constituents.