A phospholipids primer by ProQuest

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									         inform December 2009, Vol. 20 (12) 793
                                                                                                      Phospholipids



       A phospholipids primer

       Moghis U. Ahmad                                                             In the last few years, phospholipids made from marine sources
                                                                             have started to enter the nutritional supplement market. The first
                                                                             product of this kind was made from krill, a small crustacean fished
       Phospholipids are prime building blocks of all life.                  from cold Antarctic waters (for more on krill, see inform 18:588–
       The history of phospholipids begins with the isola-                   592, 2007). New phospholipid products entering the nutritional
       tion from chicken eggs of lecithin, a crude mixture                   supplement market are now made from the roe of Pacific and Atlan-
                                                                             tic Ocean cold-water fish species.
       of various phospholipids and other lipids, by the                           Structurally, phospholipid molecules consist of a hydrophilic
       French researcher Maurice Gobley around 1847.                         polar head group and a hydrophobic nonpolar tail (see Fig. 1).
       The word is derived from “lekithos,” Greek for egg                    The polar head group contains one or more phosphate groups.
                                                                             The hydrophobic tail is made up of two fatty acyl chains. When
       yolk.                                                                 many phospholipid molecules are placed in water, their hydro-
            In the 1920s, technological advances in Germany made the         philic heads tend to “face” into the water and the hydrophobic
       large-scale production of lecithin from soybeans possible. Lecithin   tails are forced to stick together at the surface, forming a bilayer.
       found applications as a nutritional supplement (i.e., a preparation   Most biologically important phospholipids are phosphoglycer-
       intended to provide nutrients that are missing or not consumed in     ides, which contain glycerol joining the head and tail. Examples
       sufficient quantities in a person’s diet). The same properties that   of phosphoglycerides include PC, PS, phosphatidylethanolamine,
       make phospholipids so important for all life forms make them          and phosphatidylinositol.
       important for food preparation, and today lecithin is widely used in        The most abundant phospholipid in cell membranes is PC,
       the food industry as an emulsifier, a wetting agent for food instan-  and therefore it is the most important building block for making
       tizing, a flow agent for chocolate manufacture, a baking stabi-       replacement membrane mass. PC has exceptional emulsifying
       lizer and pan-release slip agent, a flour improver, and an animal     properties, on which the liver draws to produce the digestive bile
       feed additive. Modern industrial processing of soy lec-
       ithin enriches its content of selected phospholipids that
       form the basis for commercially available nutraceutical
       phospholipid formulations. Currently, three phospho-
       lipids are commercially cost effective for nutritional
       supplements: phosphatidylserine (PS), phosphatidyl-
       choline (PC), and glycerophosphatidylcholine (GPC).
       All are safe to consume long-term, while offering valu-
       able proven benefits for health, such as enhancing
       brain health, protecting liver function, and serving as
       a source of choline.
            Egg yolks are the major source of phospholip-
       ids used by the pharmaceutical industry for parenteral
       nutrition, but for nutritional supplements egg phos-
       pholipids play no significant role because they have
       a relatively high cholesterol level and an unfavor-
       able saturated fatty acid profile. At one time, PS pro-
       duced from bovine brains was a widely used product
       in Europe. However, the incidence of bovine spongi-
       form encephalitis (BSE, or mad cow disease) made
       this product unusable and challenged researchers to
       find ways to isolate PS from an alternative source, such
       as soybean.                                                FIG. 1. Chemical structure of selected phospholipids.




DEC 09 INFORM.indd 793                                                                                                                     12/2/09 3:16:08 PM
                                                                                               794 inform December 2009, Vol. 20 (12)


       fluid. The lining cells of the lung and intestines use PC to make the    produce a wide variety of carrier systems that improve the solu-
       surfactant coatings essential to their gas and fluid exchange func-      bility, stability, and delivery of active pharmaceutical ingredients
       tions, and PC is the predominant building block for the circulat-        (API). The carrier system may be micelles, mixed micelles, and
       ing lipoproteins.                                                        liposomes. (Broadly defined, liposomes are lipid bilayers surround-
                                                                                ing an aqueous phase.) The emulsifyi
								
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