Synthesis of Sphingosine-1-phosphonate and Homosphingosine-1-phosphonate

Chemical Synthesis of a Very Long-Chain Fatty Acid, Hexacosanoic Acid (C26:0), and the Ceramide Containing Hexacosanoic Acid

Hexacosanoic acid (C26:0) (1), a very long-chain fatty acid, is related to various diseases such as adrenoleukodystrophy (ALD), adrenomyeloneuropathy (AMN) and atherosclerosis. As the level of 1 higher than the normal is related to diseases above, hexacosanoic acid (1) and the ceramide 2, which contains 1, are thought to play an important role in various tissues. Hexacosanoic acid (1) is known to be a waxy solid and to be hard to dissolve in water as well as organic solvents. Due to this physical property, it is not easy to handle hexacosanoic acid (1) in a laboratory. Therefore, efficient chemical synthesis of the compounds 1 and 2 has not been reported. Here, we report a versatile synthetic method for hexacosanoic acid (1) and the ceramide 2 containing the fatty acid 1. Synthesis of hexacosanoic acid (1) was achieved by applying the coupling of two alkyl units as a key step. Ceramide 2 was efficiently synthesized by applying the reported procedure together with hexacosanoic acid (1) synthesized here. This synthetic strategy has an advantage of getting various carbon chain length fatty acids and their ceramides by using a variety of carbon chain units. This method is also applicable for large-scale synthesis. In addition, these compounds 1 and 2 are useful for investigation of details of these compounds related to diseases such as ALD and AMN.

Chemical tools to investigate sphingolipid metabolism and functions

Sphingolipids comprise an important group of biomolecules, some of which have been shown to play important roles in the regulation of many cell functions. From a structural standpoint, they all share a long 2-amino-1,3-diol chain, which can be either saturated (sphinganine), hydroxylated at C4 (phytosphingosine), or unsaturated at C4 (sphingosine) as in most mammalian cells. N-acylation of sphingosine leads to ceramide, a key intermediate in sphingolipid metabolism that can be enzymatically modified at the C1-OH position to other biologically important sphingolipids, such as sphingomyelin or glycosphingolipids. In addition, both ceramide and sphingosine can be phosphorylated at C1-OH to give ceramide-1-phosphate and sphingosine-1-phosphate, respectively. To better understand the biological and biophysical roles of sphingolipids, many efforts have been made to design synthetic analogues as chemical tools able to unravel their structure-activity relationships, and to alter their cellular levels. This last approach has been thoroughly studied by the development of specific inhibitors of some key enzymes that play an important role in biosynthesis or metabolism of these intriguing lipids. With the above premises in mind, the aim of this review is to collect, in a systematic way, the recent efforts described in the literature leading to the development of new chemical entities specifically designed to achieve the above goals.