A comparison of extraction methods for the isolation of phospholipids from biological sources

Four classical methods, as well as a method presented in this paper, were compared as to their efficiency in extracting phospholipids from animal tissue. After the extractions, total lipids were separated quantitatively by DEAE-Sephadex chromatography into their acidic and nonacidic fractions. The two fractions were then further analyzed by gradient saturation high-performance thin-layer chromatography (HPTLC) combined with scanning photodensitometry after coloration with copper acetate. Of the five methods compared, the present and Christiansen's methods based upon single-phase solvent systems proved to be more efficient than biphasic extraction procedures. The undesirable discriminatory effect exhibited by biphasic solvent systems toward acidic phospholipids which were partly retained in the aqueous phase was confirmed by statistical evaluation of the HPTLC results. Total chromogenic response of acidic phospholipids extracted using biphasic solvent systems was shown to be lower by 10–35% in comparison to the single-phase method of Christiansen. The suitability of the present method for studies involving phospholipid synthesis was confirmed by monitoring the elimination of water-soluble compounds from the single-phase extracts using a classical phospholipid precursor, 2-[3H]glycerol-3-phosphate. The labeled compound was eliminated (99.3–100%) from the single-phase postcentrifugation supernatant, followed by DEAE-Sephadex chromatography.