A New Approach to the Stereospecific Synthesis of Phospholipids. The Use of l-Glyceric Acid for the Preparation of Diacylglycerols, Phosphatidylcholines, and Related Derivatives

Abstract

A new stereospecific synthesis of phospholipid derivatives of 1,2-diacyl-sn-glycerols is reported. The synthesis is based on (1) the use of L-glyceric acid as the stereocenter for construction of the optically active phospholipid molecule, (2) preparation of 3-triphenylmethyl-sn-glycerol as the key intermediate for sequential introduction of the primary and secondary acyl functions leading to the chiral diglycerides, and (3) elaboration of the sn-3-phosphodiester headgroup via phosphorylation using 2-chloro-2-oxo-1,3,2-dioxaphospholane, followed by ring opening of the five-membered phosphorus heterocycle with trimethylamine, ammonia, as well as oxygen and sulfur nucleophiles. The sequence has been shown to be suitable for the preparation of both symmetric and mixedchain diacylglycerols with saturated and unsaturated acyl substituents. Phospholipid headgroups including phosphocholine, phosphoethanolamine, phosphoethanol, and phosphoethylthioacetate functions have been prepared. Application of the method to the synthesis of functionalized phosphatidylcholines has also been demonstrated by incorporating spectroscopically active spinlabeled and fluorescent reporter groups via postsynthetic derivatization of chain terminal ω-aminoalkyl functions of the acyl substituents of the compounds. The synthetic methods developed have a great deal of flexibility, providing convenient routes to a wide range of structurally variable phospholipids for physicochemical, enzymological, and cell-biological studies.The development of new synthetic methods for the preparation of structurally well-defined phospholipid compounds has become a timely and important goal since it was discovered that in addition to their role as a major component in all biological membranes 1,2 phospholipids are also involved in a wide range of physiological and regulatory processes. 3-12 Phospholipids are essential for the functioning of a number of membrane-bound enzymes such as protein kinase C 5,10,11 and play an important role in signal transduction 4-6 as substrates for the production of second messengers 5,12 (inositol-1,4,5-trisphophate, diacylglycerol) and in the release of arachidonic acid. Significantly, some of the most potent phospholipid compounds, which are active below the micromolar 8 and nanomolar 3 levels, occur in low concentrations in the cell, such that preparation of synthetic derivatives represents a clear prerequisite to elucidation of their biochemical mechanism of action. The compounds are required for both structural and dynamic studies of biomembranes 13-16 and membrane-bound enzymes, 5,10,11,17 with particular emphasis on establishing structure-activity relationships with respect to phospholipid-phospholipid 13-16 and phospholipid-protein 17 interactions. Furthermore, delineation of the structural requirements for the biological activities of phospholipids will not only advance the current level of understanding of the chemistry and biology of these compounds but also provide important insight into the design of new target molec...

A Novel Type of Membrane Based on Cholesteryl Phosphocholine, Cholesteryl Phosphate, or Sitosteryl Phosphate, and Dimyristoylglycerol

“…The synthesis of 3 was achieved according to a procedure previously reported for the synthesis of diacylphosphatidylcholines [6] [7]. Cholesterol was first allowed to react with 2-chloro-1,3,2-dioxaphospholane 2-oxide 7, to obtain the cholesteryl cyclic phosphate 8 (Scheme 2).…”

Peptidophospholipids: Synthesis, phospholipase A2 catalyzed hydrolysis, and application to development of phospholipid prodrugs

“…Catalytic hydrolysis of the antiviral phospholipid prodrugs 10 and 13 was carried out with bee-venom phospholipase A 2 , a widely used, readily available representative of secreted PLA 2 enzymes (Arouri and Mouritsen, 2012, Arouri et al, 2013, Valentin et al, 2000) in an assay system containing Triton X-100-phospholipid mixed micelles (Roodsari, et al, 1999) in the presence of the catalytically essential Ca 2+ ions. Specifically, the phospholipid component of the micelles included a combination of the antiviral phospholipid prodrugs mixed with the natural phospholipid dipalmitoyl phosphatidylcholine (DPPC) in molar ratios of 1-to-4, and 1-to-3 respectively, using Triton X-100 as the surfactant.…”

Conformationally Constrained Analogues of Diacylglycerol (DAG). 17. Contrast between sn-1 and sn-2 DAG Lactones in Binding to Protein Kinase C

“…Acyl migration is a recognized problem in the preparation of optically active diacylglycerols and related phospholipids. 22,23 We observed that when the acyl chain is branched, acyl migration does not occur, and the final compounds (9, 10, 13, 14) could be purified safely by chromatography on silica gel. On the other hand, when the acyl chain is linear, purification of the final compounds was achieved after exhaustive washing with cold hexane or cold petroelum ether.…”