Sphingolipids chemical structure

The chemical structure of fumonisin (Fig. 5.IB) is remarkably similar to that of the sphingoid bases sphinganine (Sa) and sphingosine (So), and fumonisin has been shown to inhibit the enzyme ceramide synthase in de novo sphingolipid metabolism (Wang et al., 1991). Ceramide synthase... 

FIGURE 8.10 Chemical structure of sphingolipid identified in almond. 

In recent years, HPLC coupled with ESI-MS has become a well-established method for the identification and detection of chemical stmctures of lipids, including sphingolipids. Recently, Sugawara and coworkers [44] identified the chemical structures of glucosylceramides from maize, rice, mushroom, and sea cucumber by liquid chromatography-ion trap mass spectrometry with an ESI interface. In the positive full-scan mode, [M-t-HJ" ", [M-l-H—H2O ] , or [M-l-H—162]" (loss of glucose) was used for MS/MS analysis to obtain the product ions, which were used for the identification of the glucocerebrosides. 

Figure 10.11 Chemical structure of DM PC, important head groups of phospholipids, cholesterol, dioleoyloxypropyl trimethylammonium (DOTAP), and sphingolipid.

Sphingolipids were first described in a remarkable treatise on the chemical constitution of the brain by Johann L. W. Thudichum, a physician-scientist in London, who published his findings more than 100 years ago. A major impetus for the study of the chemistry and metabolism of the sphingolipids was the discovery of several rare human diseases that could be attributed to the abnormal accumulation of sphingolipids. This accumulation has been shown to result from a defect in catabolism that normally occurs in lysosomes. It is now known that many different kinds of sphingolipids exist, and more than 300 structures have been reported to occur in nature. 

One of the most powerful techniques used in Upid analysis today is HPLC coupled with mass spectrometry (HPLC/MS). Several mass spectrometric ionization techniques, such as fast atom bombardment (FAB) [23], electrospray ionization (ESI) [29,30], ionspray ionization (ISI) [31], and atmospheric pressure chemical ionization (APCI) [22,30,32] have been used. By using HPLC/MS, one can get information on the molecular structure of the intact lipids, which helps differentiate molecular species within different lipid classes. By using tandem mass spectrometry (MS/MS), identification of molecular species of different sphingolipids can be achieved in an easier and more sensitive way. There are many other advantages of using MS, such as small sample size, minimal sample preparation, and lack of need for derivatization, speeds, and sensitivity. In the literature, sphingolipids of both animal and plant origin were analyzed by MS. 

Figure 10 Self-assembled nanotubes can be obtained through a rolling mechanism (chiral molecular packing) or packing directly from the monomer. The structures of amphiphilic molecules used in nanotube formation (a) diacetylenic phospholipids, (b) diacetylenic N-aldonamides, (c, d, and e) glucose glycolipids, (f) sphingolipids, (g) glucophospholipid amphiphiles, (h) amphiphile with a serine head. R and R groups represent a variety of alkyl, alkenyl, or alkynyl groups. (Reproduced with permission from Ref. 52. The Chemical...

---