Plasmalogens in Biological Systems: Their Role in Oxidative Processes in Biological Membranes, their Contribution to Pathological Processes and Aging and Plasmalogen Analysis

Abstract

Plasmalogens are a specific glycerophospholipid class containing a vinyl ether moiety at the sn-1-position of the glycerol backbone. The high susceptibility of this vinyl ether bond to oxidative damage and traces of acids may indicate the possible function of plasmalogens in biological systems: The regarded cell-internal antioxidative defense of membranes by protecting other phospholipids or lipoprotein particles against oxidative stress is controversial. Reactive oxygen species preferably affect the vinyl ether function as well as the olefinic acyl residues at the sn-2-position of plasmalogens. This review is dedicated to the role of plasmalogens in different cells and tissues as spermatozoal cells or brain tissue. The first chapter of this review will discuss the molecular structure and chemistry of plasmalogen molecules, their distributions in cells and tissues and the species-specificity. In the second chapter their functions as lipid mediators will be considered and the controversial antioxidative function will be discussed. The supposed function of plasmalogens as "scavengers" for reactive oxygen species (ROS) in biological membranes is challenged by the finding that plasmalogen oxidation products as alpha-hydroxyaldehydes and plasmalogen epoxides accumulate in all chronic diseases as atherosclerosis and myocardial infarction, upon aging as well as in Alzheimers disease and other neuropathological conditions. All these conditions, characterized by increased membrane instability and oxidative damage, will be reviewed in chapter three. Chronically proceeding processes can be described by permanently invading polymorphonuclear neutrophils into inflammatory loci. The degranulation of the azurophilic granula in polymorphonuclear leukocytes causes the release of highly reactive substances, for instance the myeloperoxidase-generated hypochlorous acid (HOCl) acting as effective oxidant. Therefore, special attention will be paid to neutrophil-derived HOCl. The last chapter deals with currently used methods of detecting plasmalogens and their degradation products. Although chromatographic methods will be also discussed, special attention will be given to (31)P NMR spectroscopy and soft ionization techniques of mass spectrometry as electrospray ionization or matrix-assisted laser desorption and ionization time-of-flight mass spectrometry.

【Original Contribution】 Plasma and Erythrocyte Membrane Plasmalogen Diminished in Severe Atherosclerotic Patients Undergoing Endovascular Therapy

“…Alzheimer's disease is the main cause of senile dementia, and oxidative stress in human brain plays a pivotal role which triggers -amyloid deposition mediating neuroinflammation 12) . This line of evidence indicates that agedependent diseases such as dementia and atherosclerosis are characterized by oxidative stress and subsequent chronic inflammation under the derangement of redox condition 13) , and that plasmalogen may play a protective role against oxidative stress leading to chronic inflammation 8,9) .…”

“…evidence suggests that plasmalogen acts as an endogenous antioxidant 8,9) . Circulating erythrocytes have no intracellular organelle, and hence phospholipids are present only in the plasma membrane, indicating that plasmalogen is abundant in human erythrocyte membrane.…”

Serum Choline Plasmalogen is a Reliable Biomarker for Atherogenic Status

“…This is supported by Pls-deficient mouse, which revealed severe phenotypic alterations, including defects in CNS myelination (Gorgas et al, 2006). In addition to peroxisomal disorders, decreased brain Pls content has been reported in a number of neurological disorders such as spinal cord injury, Alzheimer's disease, Down syndrome, and multiple sclerosis (Lessig & Fuchs, 2009). The final step of PlsEtn biosynthesis is the desaturation of 1-alkyl-2-acyl-GPE via the action of Δ1 desaturase, whereas PlsCho is primarily formed from PlsEtn via polarhead group modification, by which mechanism remains still obscure (Lee, 1998).…”

Molecular Mechanisms and Physiological Significance of Organelle Interactions and Cooperation

“…Hence, one can consider them as (lipophilic) antioxidants (Lessig and Fuchs, 2009), often comparable to tocopherol with regard to potency. In vitro, plasmalogens delay the oxidative degradation of PUFAs as good as vitamin E (Engelmann et al, 1994;Reiss et al, 1997;Hahnel et al, 1999a), most likely due to the fact that the vinyl-ether bond can scavenge peroxy radicals and oxidized PUFA products.…”