Double‐bond patterns of fatty acids and alcohols in steer and human meibomian gland lipids

Nicolaides, Nicholas C.; Santos, Evelyn Cristina da Silva; Papadakis, Konstantine

doi:10.1007/bf02534454

Cited by 22 publications

(23 citation statements)

References 14 publications

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“…While small amounts of anteiso-chain branching have been reported for HFA in meibum (38), the spectrum in Figure 2A shows no interruptions in the fragmentation pattern that would be diagnostic of chain branching in the HFA portion. Likewise, CID of the AMPP-derivatized OAHFA did not yield analogous product ions for the FA chain in this structure, making it difficult to rule out the possibility of chain branching within this motif (e.g., Supporting Information, Figure S12B).…”

Section: Investigation Of Possible Methyl Chain Branchingmentioning

confidence: 70%

“…OAHFA were previously assumed to be ω-esterified based on the putative structure of the HFA liberated upon saponification (38). However, the recent discovery that FAHFA lipids exhibit a diversity of regioisomeric esters (1) demands that the position of esterification in ultra-long chain, naturally occurring OAHFA be unequivocally determined.…”

Section: Assignment Of Ester Regiochemistrymentioning

confidence: 99%

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Mass spectrometry-directed structure elucidation and total synthesis of ultra-long chain (O-acyl)-ω-hydroxy fatty acids

Hancock

Ailuri

Marshall

et al. 2018

Journal of Lipid Research

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The (O-acyl)-ω-hydroxy FA (OAHFA) comprise an unusual lipid subclass present in the skin, vernix caseosa, and meibomian gland secretions. Although they are structurally related to the general class of FA esters of hydroxy FA (FAHFA), the ultra-long chain (30-34 carbons) and the putative ω-substitution of the backbone hydroxy FA suggest that OAHFA have unique biochemistry. Complete structural elucidation of OAHFA has been challenging because of their low abundance within complex lipid matrices. Furthermore, because these compounds occur as a mixture of closely related isomers, insufficient spectroscopic data have been obtained to guide structure confirmation by total synthesis.Here, we describe the full molecular structure of ultra-long-chain OAHFA extracted from human meibum by exploiting the gas-phase purification of lipids through multi-stage mass spectrometry and novel, multidimensional ion activation methods. The analysis elucidated sites of unsaturation, the stereochemical configuration of carbon-carbon double bonds, and ester linkage regiochemistry. Such isomer-resolved mass spectrometry guided the first total synthesis of an ultra-long chain OAHFA which, in turn, confirmed the structure of the most abundant OAHFA found in human meibum, OAHFA 50:2. The availability of a synthetic OAHFA opens new territory for future investigations into the unique biophysical and biochemical properties of these lipids.

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Section: Investigation Of Possible Methyl Chain Branchingmentioning

confidence: 70%

Section: Assignment Of Ester Regiochemistrymentioning

confidence: 99%

Mass spectrometry-directed structure elucidation and total synthesis of ultra-long chain (O-acyl)-ω-hydroxy fatty acids

Hancock

Ailuri

Marshall

et al. 2018

Journal of Lipid Research

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“…The monounsaturated FA in the brain are mainly In the eye, saturated and monounsaturated VLC-FA are found in meibomian glands and their secreted meibum as well as in secretions from Harderian glands ( 1,3,(83)(84)(85)(86)(87). The FA in steer and human meibum contain a group of long-chain ␣ and omega-diols (containing two hydroxyl groups) ( 88,89 ). The omega-hydroxyl acids constituted 85% of straight-chain monounsaturated FAs, while 13% were branched-chain saturated and the remainder were branched-chain monounsaturated FAs ( 88 ).…”

Section: Nomenclature and Structure Of Vlc-fa And Vlc-pufamentioning

confidence: 99%

“…The FA in steer and human meibum contain a group of long-chain ␣ and omega-diols (containing two hydroxyl groups) ( 88,89 ). The omega-hydroxyl acids constituted 85% of straight-chain monounsaturated FAs, while 13% were branched-chain saturated and the remainder were branched-chain monounsaturated FAs ( 88 ). The major FA in meibomian gland secretions are mostly saturated and monounsaturated, with only trace amounts of VLC-PUFA ( 88 ).…”

Section: Nomenclature and Structure Of Vlc-fa And Vlc-pufamentioning

confidence: 99%

“…The omega-hydroxyl acids constituted 85% of straight-chain monounsaturated FAs, while 13% were branched-chain saturated and the remainder were branched-chain monounsaturated FAs ( 88 ). The major FA in meibomian gland secretions are mostly saturated and monounsaturated, with only trace amounts of VLC-PUFA ( 88 ). The absence of VLC-PUFA in such secretions that are exposed to the environment and the damaging effects of the UV rays from the sun is not surprising, because the double bonds of VLC-PUFA are particularly susceptible to oxidative damage by environmental factors, singlet oxygen, and UV radiation (90)(91)(92).…”

Section: Nomenclature and Structure Of Vlc-fa And Vlc-pufamentioning

confidence: 99%

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Retinal very long-chain PUFAs: new insights from studies on ELOVL4 protein

Agbaga

Mandal

Anderson

2010

Journal of Lipid Research

147

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This article is available online at http://www.jlr.org tively rare compared with the abundance of FA containing 16-22 carbons, they are widely distributed in higher plants and animals ( 1-10 ). They are found in most living organisms from humans to autotrophic and heterotrophic lower organisms, including microalgae, sponges, bacteria, and fungi ( 1,9,(11)(12)(13)(14)(15). VLC-FA are found mainly in seed oils, plant waxes, cutin, suberin, skin, hair, and wax glands ( 1 ), whereas VLC-PUFA are found primarily in retina, brain ( 1, 16 ), testis, and spermatozoa ( 17-19 ).The unusually long hydrocarbon chains with 3 -9 double bonds, which are prone to oxidative damage, combined with the small quantities found in mammalian tissues, have made them diffi cult to isolate and analyze in detail over the years ( 9 ). Very little is therefore known about the metabolism and function of VLC-PUFA and VLC-FA in mammals, except for their increase in disorders of peroxisomal function ( 3,16,20,21 ), as components of the secretions of meibomian glands (22)(23)(24)(25)(26)(27), and their reduction in animal models of autosomal dominant Stargardt-like macular dystrophy (STGD3) ( 28-32 ), a juvenile form of macular degeneration. In contrast, the roles of long-chain PUFA (LC-PUFA) with carbon chains that range from C18 to C24 are fairly well understood, especially in the retina and other neural tissues. A detailed account on the role and function of LC-PUFA in the retina was reviewed earlier (33)(34)(35)(36).Recent interest in the molecular and physiological roles of VLC-PUFA in the retina came from the fi nding that the gene associated with STGD3 shared sequence homologies with genes involved in FA elongation ( 37,38 ) Abbreviations: AOX, acyl-CoA oxidase; DHA or 22:6n3, docosahexaenoic acid; ELOVL, elongation of very long-chain FA; ELOVL4, elongation of very long-chain FA-4; ERG, electroretinogram; LC-PUFA, long-chain PUFA; PC, phosphatidylcholine; ROS, retinal outer segments; RPE, retinal pigment epithelium; STGD1, recessive Stargardt degeneration; STGD3, autosomal dominant Stargardt-like macular dystrophy; VLC-FA, very long-chain saturated or monounsaturated FA; VLC-PUFA, very long-chain PUFA.

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