Phospholipids

Phospholipids are a class of lipids that are a major component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid “tails” and a hydrophilic “head” consisting of a phosphate group. The two components are joined together by a glycerol molecule. The phosphate groups can be modified with simple organic molecules such as choline, ethanolamine or serine.

The first phospholipid identified in 1847 as such in biological tissues was lecithin, or phosphatidylcholine, in the egg yolk of chickens by the French chemist and pharmacist, Theodore Nicolas Gobley. Biological membranes in eukaryotes also contain another class of lipid, sterol, interspersed among the phospholipids and together they provide membrane fluidity and mechanical strength. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science.

In other words, phospholipids (PLs) are amphiphilic lipids found in all plant and animal cell membranes, arranged as lipid bilayers. The PLs found in most cell membranes are basically glycerophospholipids (GPLs).

There is a growing scientific rationale for the use of dietary PLs for the treatment of inflammatory diseases to regulate the inflammatory reaction.

The oral supplementation with dietary PLs has been investigated extensively in relation to blood lipid profiles and cardiovascular risks. Several authors reported a significant total cholesterol lowering effect of soybean PLs in patients with primary hyperlipidaemia.

Age related memory impairment represents a gradual, but physiologically normal deterioration of memory function, which affects virtually every human being. It is known that during aging the lipid composition of brain cells changes. The amount of polyunsaturated n-3 FAs (3-PUFA) in the brain tends to decrease with age, consequently membrane fluidity is decreased and cholinergic activities via retarded Na+- and Ca+-channels in the membranes are reduced, since they require PC and PUFAs for their excitability and neurotransmitter release.

The cholesterol/PL ratio (C/PL) in the cell membrane increases with age. These changes in the composition of cell membranes have consequences for their properties and functions.

GPLs have been widely prescribed for the treatment of hepatic disorders including viral hepatitis and alcohol induced liver damage. A recent review by Gundermann et al. shows that essential PLs (purified extract of PPC derived from soybean) are indeed beneficial in the mentioned hepatic disorders.

GPLs, even though being “only” a food-component, are able to interact with the cellular membranes, changing their compositions (and probably their lipid microstructure and the lipid rafts) and thereby influencing a vast quantity of signaling processes and enzymatic activities.