Identification of Furan Fatty Acids as Minor Components of Human Lipids by Multidimensional GC-MSD

Significance of the Topic

Furan fatty acids (F-acids) are trace-level lipids found across diverse biological systems and have been implicated as precursors of bioactive furanpropionic acids. Their detection in human blood components and milk offers insights into metabolic pathways and potential toxicological effects. Sensitive and selective methods are thus essential to profile these minor constituents directly in complex matrices.

Objectives and Study Overview

• Identify and characterize furan fatty acids in human plasma, red blood cells, platelets, and milk.
• Compare the occurrence of F-acid 10 in human and bovine milk.
• Develop a streamlined workflow using multidimensional GC-MSD that eliminates pre-fractionation steps.

Methodology and Instrumentation

• Sample Preparation: Folch lipid extraction followed by direct transesterification under nitrogen to form fatty acid methyl esters.
• Single-Column GC-MS: HP 5890/5971 system with a 25 m×0.2 mm HP-1 column, temperature program 130→300 °C at 2 °C/min, split ratio 1:10.
• Multidimensional GC-MSD: Two GC ovens linked by a heated transfer line and cryotrap (CTS-1), cold injection system (CIS-3), and timed column switching to enrich furan fatty acid cuts.
• Columns: Pre-column HP-1 (25 m×0.32 mm, df=1.05 μm); main column Stabilwax (30 m×0.25 mm, df=0.25 μm).
• Detection: FID in the first GC and MSD (HP 5972A, scan range 50–450 amu) in the second GC.

Key Results and Discussion

• Major fatty acids in blood and milk were palmitic (C16:0), linoleic (C18:2 ω6), oleic (C18:1 ω9), stearic (C18:0), and arachidonic (C20:4 ω6).
• Table I (summarized) shows serum rich in linoleic (~30 %), platelets enriched in arachidonic (~22 %), and milk with high C14:0 and C16:0.
• F-acid 10 (12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic acid) was found in all blood components and one human milk sample, matching bovine milk.
• F-acid 8 appeared in red blood cells and plasma; F-acid 5 only in red blood cells.
• Direct transesterification enabled simultaneous detection of furanpropionic acids (e.g. 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid) and F-acids, reinforcing precursor relationships.

Benefits and Practical Applications

• Streamlined analysis without laborious fractionation allows high-throughput profiling of trace lipid components.
• Supports metabolic and toxicological studies by direct identification of F-acids and related propionic acids in clinical samples.
• Applicable to nutritional research, lipidomics, and biomarker discovery in biomedical and QA/QC contexts.

Future Trends and Potential Applications

• Extending the approach to tissue analyses for comprehensive mapping of F-acid distribution.
• Integration with high-resolution and tandem mass spectrometry for detailed structural elucidation of novel F-acids.
• Applying quantitative multidimensional GC-MSD methods in large-scale epidemiological and pharmacokinetic studies.
• Exploring links between dietary intake of F-acids, furanpropionic metabolites, and disease outcomes.

Conclusion

The multidimensional GC-MSD method enables direct, sensitive, and selective identification of minor furan fatty acids in human blood and milk without pre-separation. Detection of both F-acids and furanpropionic acids in serum supports the metabolic precursor hypothesis and underscores the utility of this approach in analytical lipidomics.

Used Instrumentation

• Hewlett-Packard HP 5890/5971 GC-MS system with HP 7673 autosampler.
• Gerstel CIS-3 cold injection system and CTS-1 cryotrap.
• Pre-column HP-1 (25 m×0.32 mm, df=1.05 µm); main column Stabilwax (30 m×0.25 mm, df=0.25 µm).
• Detectors: FID (GC 1) and MSD (HP 5972A, 50–450 amu) in GC 2.

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