Determination of Neutral Lipids and Phospholipids in the Cercariae of Schistosoma Mansoni by High Performance Thin Layer Chromatography

High performance thin layer chromatography (HPTLC) was used to analyze neutral lipids and phospholipids in the cercariae of a Puerto Rican strain of Schistosoma mansoni. The cercariae were obtained following isolation of Biomphalaria glabrata snails (NMRI strain) experimentally infected with S. mansoni miracidia. Cercariae were pelleted to contain from 1000 to 10,000 organisms per 1.5 mL of artificial spring water and then extracted in chloroform–methanol (2 : 1). The lipid extract was analyzed by previously published silica gel HPTLC methods, using a petroleum ether–diethyl ether–acetic acid (80 : 20 : 1) mobile phase and detection with phosphomolybdic acid spray reagent for neutral lipids. Visual observations of the chromatograms showed that the most abundant neutral lipids in the cercariae were free fatty acids and free sterols along with two additional faster moving zones that did not match the methyl oleate and cholesteryl oleate standard zones. Quantification of the free fatty acid and free sterol fractions by scanning densitometry revealed mean weights±standard deviation of 4.62±1.9 ng and 3.51±0.70 ng per cercaria, respectively. Phospholipids were separated on silica gel using a mobile phase of chloroform–methanol–water (65 : 25 : 4), and the plates were sprayed with a detection reagent of 10% cupric sulfate in 8% phosphoric acid. Visual observations of the chromatograms showed that the most abundant phospholipids were phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Quantification of PC and PE by scanning densitometry revealed mean weights±standard deviation of 67.0±18 ng and 38.7±8.8 ng per cercaria, respectively. This is the first study to provide quantitative data on neutral lipids and phospholipids on a per cercaria basis for S. mansoni. The possible functions of lipids and phospholipids in cercariae are discussed.