Acylglycerols and Related Lipids

Abstract

Glycerol serves as the alcohol backbone for a wide variety of lipids. Fatty acids generally do not occur in nature as free acids, but primarily as esters with glycerol called acylglycerols (acylglycerides). Glycerol may be fully acylated (triacylglycerols or triglycerides) or only partially acylated (mono- and diacylglycerols or mono- and diglycerides). In some cases a mono- or diglyceride may be substituted at the third carbon with phosphate or a phos-phorylated substance (phosphorylcholine, phosphorylserine, etc.) via a phosphodiester bond (phosphoglyceride or phospholipid) , or with a sugar (glycosylglycerol). Phospholipids are the subject of the next chapter (Chapter 6). Some glycerides may contain hydroxylated acyl groups that may in turn be esterified to long chain fatty acids to form esto-lides (tetra-, penta-, and hexaglycerides). Aliphatic chains may also be linked to a diglyceride via an ether (alkyl) or vinyl ether (alkenyl) linkage. The latter type of lipid is called a neutral plasmalogen. Structures of these lipids are given in Figure 5.1.