Top-down lignomic matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry analysis of lignin oligomers extracted from date palm wood

Tasahil Albishi; Abanoub Mikhael; Fereidoon Shahidi; Travis D Fridgen; Michel Delmas; Joseph Banoub

doi:10.1002/rcm.8368

Top-down lignomic matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry analysis of lignin oligomers extracted from date palm wood

Rapid Commun Mass Spectrom. 2019 Mar 30;33(6):539-560. doi: 10.1002/rcm.8368.

Authors

Tasahil Albishi¹, Abanoub Mikhael², Fereidoon Shahidi¹, Travis D Fridgen², Michel Delmas³, Joseph Banoub^{1

2

4}

Affiliations

¹ Department of Biochemistry, Memorial University of Newfoundland, St John's, Newfoundland, A1C 5X1, Canada.
² Department of Chemistry, Memorial University of Newfoundland, St John's, Newfoundland, A1C 5X1, Canada.
³ Inp-Ensiacet, Chemical Engineering Laboratory 4, University of Toulouse, Allée Emile Monso, 31432, Toulouse, France.
⁴ Science Branch, Special Projects, Fisheries and Oceans Canada, St John's, NL, A1C 5X1, Canada.

PMID: 30506948
DOI: 10.1002/rcm.8368

Abstract

Rationale: We report for the first time the top-down lignomic analysis of the virgin released lignin (VRL) oligomers obtained from the Saudi date palm wood (SDPW), using a matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) instrument. In addition, we are proposing new collision-induced dissociation tandem mass spectrometry (CID-MS/MS) fragmentation routes for this series of unreported VRL oligomers.

Methods: We have used direct MALDI-TOF-MS analysis of the mixture of lignin oligomers without any chromatographic pre-separation. High-energy CID-MS/MS analyses were used to confirm the precursor ion structures.

Results: Six protonated lignin oligomer molecules were identified: [C₁₉ H₂₄ O₈ + H]⁺ as H(8-O-4')G; [C₅₀ H₅₂ O₁₉ + H]⁺ as H(8-O-4')H(8-O-4'')S(8-O-4''')S(8-O-4'''')G; [C₅₈ H₅₄ O₁₈ + H]⁺ as H(8-O-4')H(8-O-4'')H(8-O-4''')G(8-O-4'''')S(8-O-4''''')G; [C₅₈ H₅₄ O₁₉ + H]⁺ as H(8-O-4')H(8-O-4'')H(8-O-4''')S(8-O-4'''')S(8-O-4''''')G; [C₆₁ H₆₈ O₂₅ + H]⁺ as H(8-O-4')G(8-O-4'')G(8-O-4''')S(8-O-4'''')S(8-O-4''''')G; and [C₆₁ H₆₈ O₂₆ + H]⁺ as C(8-O-4')G(8-O-4'')G(8-O-4''')S(8-O-4'''')S(8-O-4''''')G units (H = coniferyl, S = sinapyl, and G = p-coumaryl). Two distonic cations were identified as [C₃₉ H₄₃ O₁₅ + H]^+• and [C₄₀ H₄₃ O₁₆ + H]^+• deriving from two tetrameric lignin oligomers. The high-energy MS/MS analyses allowed the confirmation of the proposed structures of this series of lignin oligomers.

Conclusions: To our knowledge, this is the first elucidation of the lignin structure of the Saudi seedling date palm wood that was accomplished using a top-down lignomic strategy that has not previously been published. The complex high-energy CID-MS/MS fragmentations presented herein are novel and have never been described before.

Grants and funding

CIMV