Synthesis of phosphatidylcholine analogues derived from glyceric acid: a new class of biologically active phospholipid compounds

Abstract

Synthesis of a new class of phosphatidylcholine analogues derived from glyceric acid is reported for spectroscopic studies of phospholipases and conformation of phospholipid side-chains in biological membranes, using fluorescence resonance energy transfer (FRET) techniques. Biologically active synthetic phospholipid compounds are required for structural and dynamic studies of biomembranes for establishment of structure-activity relationships with respect to phospholipid-phospholipid and phospholipid-protein interactions, as well as for mechanistic studies of phospholipid metabolizing enzymes. 1-3 Specifically, with the discovery that phospholipases generate a number of physiologically important lipid metabolites, including second messengers that are involved in cell signaling, 1 development of new synthetic methods for preparation of phospholipid derivatives became a key step in advancing membrane biochemistry. Phospholipid analogues incorporating spectroscopically active reporter groups have been shown to be valuable structural probes to study conformation and dynamics of phospholipids in aggregates (e.g. micelles, bilayers, and vesicles) as well as for development of spectroscopic assay systems of lipolytic enzymes, 4-6 and for in vivo monitoring the fate of products generated by phospholipids metabolizing enzymes. 7 As a part of our work in this area we focused on development of highly specific fluorescent phospholipase A 2 substrates for kinetic studies and for detection of in vivo activity of the enzyme. Phospholipases A 2 (PLA 2 , EC 3.1.1.4) comprise a large group of intracellular and secreted enzymes that catalyze the hydrolysis of the sn-2 ester function of glycerophospholipids to produce free fatty acids, such as arachidonic acid, and lysophospholipids. 8 Both products are precursors of signaling molecules with a multitude of biological functions. [8][9][10][11][12][13] Specifically,

Synthesis of phospholipids on a glyceric acid scaffold: design and preparation of phospholipase A2 specific substrates

“…The underlying working hypothesis in the design of the target compounds (Figure 2) was inspired by our earlier discovery that structural modification of the sn -1-position of the natural phospholipid, introducing an inverse ester function to prevent PLA 1 activity, yielded analogues that could readily be hydrolyzed at the sn -2-ester group by sPLA 2 enzymes. 11 Indeed, studies in other laboratories have also shown, that secretory PLA 2 s well tolerate a range of structural modifications at the neighboring sn -1-substitution 12 using analogues that readily undergo catalytic hydrolysis at the sn -2-position by the enzyme. Thus, we have designed two principal target structures 3 and 4 as platforms for preparation of the PLA 2 -directed substrates: incorporating at the sn -1-position glyceric acid derivatives of an ester group in 3 , and an amide group in 4 , to prevent cleavage by PLA 1 , as well as by other, non-specific esterase enzymes.…”

Assay and inhibition of diacylglycerol lipase activity

“…43–47 This series of novel ether lipid molecules was synthesized (Scheme 2) with the biomimetic stereochemistry at sn -2 and incorporated terminally functionalized sn -1 and sn -2 fatty acyl groups. The epoxide of ( R )-(-)-glycidyl methyl ether ( 23 ) was opened with benzyl alcohol and sodium hydride followed by silyl protection of the secondary alcohol 24 , and hydrogenolysis of the benzyl ether 25 in ethanol/ethyl acetate/acetic acid (1:1:0.2).…”

Stepwise synthesis of 2,3-<i>O</i>-dipalmitoyl-D-glyceric acid and an in vitro evaluation of its cytotoxicity

“…In previous reports, GA diacylesters were demonstrated to be synthesized from isopropylidene protected methyl glycerate, which is commercially available, with high yields 18,19 . However, considering that GA calcium salts are effi ciently produced in our fermentation process 5 , it is of great signifi cance to use GA calcium salts as a starting material.…”