Characterization of isomeric allylic diols resulting from chlorophyll phytyl side‐chain photo‐ and autoxidation by electron ionization gas chromatography/mass spectrometry

Abstract

The electron ionization (EI) mass spectral fragmentation of the trimethylsilyl derivatives of 3-methylidene-7,11,15-trimethylhexadecane-1,2-diol, Z- and E-3,7,11,15-tetramethylhexadec-3-ene-1,2-diols and Z- and E-3,7,11,15-tetramethylhexadec-2-ene-1,4-diols resulting from chlorophyll phytyl side-chain photo- and autoxidation was investigated. Different pathways (substantiated by deuterium labelling) were proposed in order to explain the main fragmentation observed. Then, some sufficiently specific fragment ions were selected and used to characterize these compounds in natural environmental samples.

The Critical Role of Arabidopsis Electron-Transfer Flavoprotein:Ubiquinone Oxidoreductase during Dark-Induced Starvation

“…In plants, phytol is derived from the first step of chlorophyll degradation, which is catalyzed by chlorophyllase (EC 3.1.1.14) (Tsuchiya et al, 1999); however, the latter enzymatic steps of phytol degradation are poorly understood, especially in comparison with the pathway in humans. Previous studies have suggested that phytol degradation during leaf senescence occurs via photooxidative conversion into various isoterpenoid compounds (Rontani et al, 1996;Matile et al, 1999;Rontani and Aubert, 2005). This obviously cannot be the case for chlorophyll breakdown during the extended dark treatments in this study.…”

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP25 in Arctic sediments

“…Quantification was thus carried out with standards of two highly structurally related compounds. Diol 2 was quantified using an external standard of 3,7,11,15‐tetramethylhexadecan‐1,2‐diol ( 4 ) produced by Pd/CaCO 3 ‐catalyzed hydrogenation of 3‐methylidene‐7,11,15‐trimethylhexadecan‐1,2‐diol ( 5 ) whose synthesis was described previously, while quantification of acid 3 was carried out with 2,6,10,14‐tetramethylpentadecanoic acid (pristanic acid) ( 6 ) (Sigma Aldrich, St. Quentin Fallavier, France).…”

“…Due to the very low amounts of IP 25 available, compounds 2 and 3 could not be produced in sufficient amounts to permit quantification, although comparison of their mass fragmentations and retention times with those of compounds detected in sediments allowed their hydrogenation of 3-methylidene-7,11,15-trimethylhexadecan-1,2-diol (5) whose synthesis was described previously, 12 while quantification of acid 3 was carried out with 2,6,10,14-tetramethylpentadecanoic acid (pristanic acid) (6) (Sigma Aldrich, St. Quentin Fallavier, France).…”

Autoxidative and Photooxidative Reactivity of Highly Branched Isoprenoid (HBI) Alkenes

“…The synthesis of 3-methylidene-7,11,15-trimethylhexadecan-1,2-diol (phytyldiol), 3,7,11,15-tetramethylhexadec-3(Z/E)-en-1,2-diols and 3,7,11,15-tetramethylhexadec-2en-1,4-diols was described previously [28]. 24-Methylcholesta-5,22-dien-3b-ol and 24-methylcholesta-5,24 (28)-dien-3b-ol were purchased from Sigma-Aldrich.…”