Phospholipids of Animal and Marine Origin: Structure, Function, and Anti-Inflammatory Properties

Abstract

In this review paper, the latest literature on the functional properties of phospholipids in relation to inflammation and inflammation-related disorders has been critically appraised and evaluated. The paper is divided into three sections: ^{Section 1} presents an overview of the relationship between structures and biological activities (pro-inflammatory or anti-inflammatory) of several phospholipids with respect to inflammation. ^{Section 2} and ^{Section 3} are dedicated to the structures, functions, compositions and anti-inflammatory properties of dietary phospholipids from animal and marine sources. Most of the dietary phospholipids of animal origin come from meat, egg and dairy products. To date, there is very limited work published on meat phospholipids, undoubtedly due to the negative perception that meat consumption is an unhealthy option because of its putative associations with several chronic diseases. These assumptions are addressed with respect to the phospholipid composition of meat products. Recent research trends indicate that dairy phospholipids possess anti-inflammatory properties, which has led to an increased interest into their molecular structures and reputed health benefits. Finally, the structural composition of phospholipids of marine origin is discussed. Extensive research has been published in relation to ω-3 polyunsaturated fatty acids (PUFAs) and inflammation, however this research has recently come under scrutiny and has proved to be unreliable and controversial in terms of the therapeutic effects of ω-3 PUFA, which are generally in the form of triglycerides and esters. Therefore, this review focuses on recent publications concerning marine phospholipids and their structural composition and related health benefits. Finally, the strong nutritional value of dietary phospholipids are highlighted with respect to marine and animal origin and avenues for future research are discussed.

Keywords: anti-inflammatory; atherosclerosis; dairy; egg; inflammation; marine; meat; nutrition; phospholipids.

Figure 1

The most common structures of phospholipids are depicted: phospholipids with a glycerol backbone (GPLs); sphingomyelin as a representative of a sphingosine-backbone phospholipid (SPLs); and alkyl-phospholipids (Alkyl-GPLs) that have a fatty chain linked with an ether-bond at the sn-1 position of the glycerol backbone.

Figure 2

Illustration of the milk fat globule membrane. The sizes in this schematic are not in proportion. A phospholipid monolayer surrounds the triacylglycerol core, followed by a proteinaceous coat connecting the monolayer to the outer phospholipid bilayer. Adipophilin (ADPH) is located in the inner layer polar lipid layer, while xanthine dehydrogenase/oxidase (XDH/XO) is located between both layers. PE, PS and PI are generally concentrated on the inner surface of the membrane, whereas PC, SM, glycolipids (G), cerebrosides and gangliosides are mainly located in the external membrane. SM and cholesterol (C) can form rigid domains in the cellular membrane known as lipid rafts. Glycoproteins are distributed over the external membrane surface; these include butyrophilin (BTN), Mucin 1 (MUC1), PAS 6/7 and CD36.

Figure 3

Structures of bioactive marine phospholipids as elucidated previously by Sioriki et al. and Nasopoulou et al. [80,85]. Generally, PC and PE derivatives exhibit the greatest bioactivity in marine sources.