PubMed · 4383877
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G D Copeland. 1967. Beta adrenergic blockade.. https://pubmed.ncbi.nlm.nih.gov/4383877/
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[reaction: see text] Truncated ethanolamine phospholipids containing aldehyde functionality, e.g. OVPE, and the corresponding acids, are generated by oxidative cleavage of polyunsaturated phospholipids. To confirm their identities and facilitate studies of the chemistry and biological actions of these analogues of biologically active phosphatidylcholines, e.g. OVPC, total syntheses were developed. An efficient general strategy was used that features selective N-protection of 2-lysophosphatidylethanolamine, and generation of the target compounds by mild deprotection of stable precursors.
1D and 2D 1H and 13C NMR spectra of the assumed [MoO(4)(TEA)](2-) complex recorded in DMSO at variable temperatures clearly indicate one free and two bound hydroxyethyl arms. The free arm of the ligand readily exchanges with the two metal-bound arms. Under such conditions the triethanolamine (TEA) acts as a bidentate ligand. The presence of water accelerates the exchange, which at higher water content involves the free ligand too. In organic solvents the binding strength of the hydroxo groups to the molybdenum is weaker than that of the water molecules. A plausible structure is confirmed by 14N, 17O and 95Mo measurements and an exchange mechanism based on the existence of an eight-membered relatively rigid chelate ring is suggested.
N-Acylethanolamines (NAEs) constitute a new class of plant lipids and are thought to play a role in plant defense strategies against pathogens. In plant defense systems, oxylipins generated by the lipoxygenase pathway are important actors. To date, it is not known whether plants also use endogeneous oxylipins derived from NAEs in their defense reactions. We tested whether members of the NAE class can be converted by enzymes constituting this pathway, such as (soybean) lipoxygenase-1, (alfalfa) hydroperoxide lyase and (flax seed) allene oxide synthase. We found that both alpha-N-linolenoylethanolamine and gamma-N-linolenoylethanolamine (18:3), as well as alpha-N-linolenoylamine and gamma-N-linolenoylamine were converted into their (13S)-hydroperoxide derivatives by lipoxygenase. Interestingly, only the hydroperoxides of alpha-N-linolenoyl(ethanol)amines and their linoleic acid analogs (18:2) were suitable substrates for hydroperoxide lyase. Hexanal and (3Z)-hexenal were identified as volatile products of the 18:2 and 18:3 fatty acid (ethanol)amides, respectively. 12-Oxo-N-(9Z)-dodecenoyl(ethanol)amine was the nonvolatile hydrolysis product. Kinetic studies with lipoxygenase and hydroperoxide lyase revealed that the fatty acid ethanolamides were converted as readily or even better than the corresponding free fatty acids. Allene oxide synthase utilized all substrates, but was most active on (13S)-hydroperoxy-alpha-N-linolenoylethanolamine and the (13S)-hydroperoxide of linoleic acid and its ethanolamine derivative. alpha-Ketols and gamma-ketols were characterized as products. In addition, cyclized products, i.e. 12-oxo-N-phytodienoylamines, derived from (13S)-hydroperoxy-alpha-N-linolenoylamines were found. The results presented here show that, in principle, hydroperoxide NAEs can be formed in plants and subsequently converted into novel phytooxylipins.