Aziridination-Assisted Mass Spectrometry of Nonpolar Sterol Lipids with Isomeric Resolution

Area of Science:

• Lipidomics
• Mass Spectrometry
• Organic Chemistry

Background:

• Nonpolar lipids, particularly sterols, are vital in biological systems.
• Their diverse structures, including various isomeric forms, pose analytical challenges.
• Accurate characterization is essential for understanding biological functions.

Purpose of the Study:

• To develop a novel method for characterizing nonpolar sterol lipids.
• To target carbon-carbon double bonds (C═C bonds) in sterols using N-H aziridination.
• To improve the sensitivity, accuracy, and specificity of nonpolar lipid analysis.

Main Methods:

• Introduction of the N-H aziridination method targeting C═C bonds in sterols.
• Utilizing collision-induced dissociation (CID) for fragment ion generation.
• Analysis of fragmentation patterns for C═C bond position and sterol backbone determination.
• Demonstration of quantitative analysis with a limit of detection (LOD) of 10 nM.

Main Results:

• Aziridination facilitates specific fragmentation, enabling precise C═C bond localization.
• Distinct fragmentation pathways differentiate chain and ring C═C bonds in sterols.
• Identification of sterol isomers like desmosterol and 7-dehydrocholesterol was achieved.
• Fingerprint tandem mass spectra aided in sterol backbone characterization.
• The method demonstrated quantitative capacity with high sensitivity.
• Significant differences in nonpolar lipid profiles were observed in mouse prostate cancer tissues.

Conclusions:

• N-H aziridination is an effective strategy for characterizing nonpolar sterol lipids.
• The method enhances ionization efficiency, improving analytical sensitivity and accuracy.
• It enables precise identification of sterol isomers and backbone structures.
• Aziridination-assisted mass spectrometry is suitable for quantitative analysis in complex biological samples.
• This approach holds significant potential for broad applications in nonpolar lipid research, including disease biomarker discovery.