Barrier properties of lecithin/lysolecithin mixtures

Light scattering, birefringence and X-ray studies showed that liposomes with lipid molecules orientated in bilayers, are formed from egg lecithin/lysolecithin mixtures up to 50 mol% of lysolecithin; above this concentration much smaller mixed micelles are formed. Permeability studies demonstrated a dramatic increase in the permeability of the liposomes when the lyso concentration exceeds 22.5 mol% X-ray studies indicated a significant decrease in bilayer thickness with increasing lysolecithin concentration. It is suggested that decreased interaction energy between the lipid molecules in the bilayer i

Studies on the lysis of red cells and bimolecular lipid leaflets by synthetic lysolecithins, lecithins and structural analogs

The results obtained in this study show a great influence of the acyl chain on the lytic behavior of lysolecithins and lecithins. 1. 1.The lysolecithins studied, ranged in acyl chain length from 10 to 18 carbon atoms.The palmitoyl- and stearoylderivatives were found to be the most active, whereas the shortchain compounds like decanoyl-lysolecithin showed no activity at all.The possible influence of the glycerolic hydroxylgroup was studied by means of 8 different desoxy-lysolecithins, varying in chain length from 12 to 26 carbon atoms.This structural modification, however, turned out to be negligible. The highest activity was also found for compounds with 16 and 18 carbon atoms, while the shorter and longer chain ones (lauroyl C12, myristoyl C14, arachidoyl C20) were less active, or not active at all (behenoyl C26, cerotoyl C22).Introduction of double bonds in the acyl chain also rendered the compounds less active (oleoyl-lysolecithin, linoleoyl-lysolecithin). 2. 2.Structural variations in the desoxycompounds, like extension of the alkanediol skeleton of the molecule, or increase of the distance between the phosphate group and the quaternary ammonium moiety had virtually no effect. 3. 3.It was observed that lecithins with a chain length from 8 to 12 carbon atoms (per acyl chain) are capable of lysing red cells.The lecithin with highest activity was found to be di-undecyloyl-lecithin, which was almost as active as the most potent lysolecithin.Shortening or lengthening of the acyl chains diminished the lytic activity, just as in the case of the lysolecithins and the desoxy-lysolecithins.Therefore it is concluded that lysolecithins, desoxy-lysolecithins and lecithins reveal maximum lytic activity at a distinct chain length. 4. 4.It appears that the action of lysolecithins, desoxy-lysolecithins and lecithins toward red cells and lipid bilayers shows reasonable similarity with the exception of some unsaturated compounds. This might indicate that the interaction of the lytic agents with the lipid-constituents of the membrane plays an important role in the process