CHOLESTEROL SOLUBILIZING CAPACITY OF LECITHINS IN AQUEOUS SOLUTIONS OF BILE SALT

These experiments tested the hypothesis that lecithins which had dissimilar fatty acid compositions would have differing abilities to solubilize cholesterol in an aqueous solution of bile salts. The ability of ten synthetic lecithins to solubilize cholesterol was determined in an assay system in which aqueous mixtures of 10 mM lecithin, 20 mM glycocholate, and cholesterol were irradiated with ultrasound, and then were equilibrated at 37°. The cholesterol solubilizing capacities of dilinoleoyl lecithin and of dioleoyl lecithin were higher than those of dipalmitoyl lecithin or of distearoyl lecithin. There were no differences, however, among lecithins which contained both saturated and unsaturated fatty acids except that 1-palmitoyl, 2-oleoyl lecithin had a greater cholesterol solubilizing capacity than did 1-oleoyl, 2-palmitoyl lecithin. 10 mM of 1-palmitoyl lysolecithin could solubilize cholesterol, whereas mixtures of 1-oleoyl lysolecithin above 0.70 mM were turbid in buffered glycocholate. Because bile contains predominantly 1-saturated, 2-unsaturated acyl lecithins, these data are probably not relevant to the pathogenesis of human cholesterol gall stones. © 1969.