Adosraku, Reimmel Kwame; (1994) Nuclear magnetic resonance and chromatographic studies of host and parasite lipids. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

One-dimensional and 2-dimensional proton nmr techniques were used to characterise and quantify lipids extracted from host (blood) and parasites including Leishmania donovani, L. major, L. mexicana, L. infantum, Giardia lamhlia. Entamoeba histolytica and the non- parasitic protozoan, Tetrahymena thermophila. Phospholipid classes and subclasses, sterols, triglycerides, metabolic changes in lipids as well as fatty acid composition of glycerophospholipids were determined from structure-specific proton resonances and confirmed by cross peaks in the 2-D COSY spectra of lipid extracts. Phosphatidylcholine, ethanolamine phospholipids and sphingomyelin were the principal phospholipids found in the erythrocyte membrane. Cholesterol, the only neutral lipid, was present in roughly equal proportion to the total phospholipids. Ethanolamine lipids were present in diacyl and alkenylacyl forms. Phosphatidylcholine was the major phospholipid in the plasma and was quantified together with cholesterol, cholesterol esters, triglycerides and lysophospholipids. Leishmania lipid composition differed substantially from the hosts. The major phospholipids determined were those of choline, ethanolamine and inositol. The choline lipids were mainly diacyl, the ethanolamine lipids were predominantly plasmenyl while the inositol lipids existed in diacyl, alkylacyl and ceramide forms. Several sterols were detected from nmr spectra where parasite-specific ergosterol-type sterols exceeded cholesterol. The glycerophospholipids of Giardia (phosphatidylglycerol as major lipid) and Entamoeba (phosphatidylcholine as major lipid), unlike blood and Leishmania, carried predominantly saturated and monounsaturated fatty acids and were present in the diacyl form. From Tetrahymena, the determination of phosphonolipids in addition to normal phospholipids was achieved; its lipid extract contained a high proportions of alkylacyl forms. The successful analysis of 1-acyl and 2-acyl-lysophospholipids from plasma, Leishmania and Entamoeba makes the application of proton nmr to the study of phospholipases A desirable. These analyses agreed substantially with other published information and therefore, makes proton nmr potentially useful in future parasite lipid research.

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