Identifying citrus limonoid aglycones by HPLC-EI/MS and HPLC-APCI/MS techniques.

Area of Science:

• Analytical Chemistry
• Natural Product Chemistry
• Mass Spectrometry

Background:

• Limonoids are a diverse class of compounds found in citrus fruits.
• Accurate identification and structural elucidation of limonoids are crucial for understanding their biological activities and potential applications.
• Existing analytical methods may require further refinement for comprehensive citrus limonoid profiling.

Purpose of the Study:

• To identify known neutral limonoid aglycones from citrus sources.
• To establish a reliable analytical method for structural characterization of citrus limonoids.
• To explore the utility of HPLC-MS with EI and APCI for differentiating limonoid structures.

Main Methods:

• High-Performance Liquid Chromatography (HPLC) coupled with Mass Spectrometry (MS).
• Utilized normal phase HPLC with Electron Ionization (EI) and Atmospheric Pressure Chemical Ionization (APCI) MS.
• Correlated EI fragmentation patterns and APCI-derived molecular weights with known limonoid structures.

Main Results:

• Successfully identified 17 known neutral limonoid aglycones from citrus.
• Generated characteristic chromatographic, molecular weight (APCI), and fragmentation (EI) data for each identified limonoid.
• Demonstrated the combined utility of EI fragmentation and APCI molecular weight data for structural elucidation.

Conclusions:

• HPLC-MS, utilizing both EI and APCI ionization techniques, provides comprehensive data for limonoid identification.
• The established method offers a robust approach for discerning the structural characteristics of unknown citrus limonoids.
• This analytical strategy can aid in the discovery and characterization of novel limonoid compounds.