ABSTRACT

Hydrogenation is a well-known method in the chemistry and technology of lipids, fats, and oils; however, it has been mostly restricted to treatment of nonaqueous solutions or solvent-free liquid substrates. In general, heterogeneous catalysts give low rates when applied to aqueous lipid dispersions, and the classical homogeneous catalysts are usually insufficiently soluble in water to be useful for hydrogenation of liposomes and biomembranes. Hydrogenation of lipids either in the form of aqueous dispersions or as constituents of biomembranes can be achieved under biologically acceptable conditions. The newly emerging technique of deuteration coupled with infrared spectroscopy detects the conformational order around specifically labeled segments of the acyl chains inside the lipid bilayer. Homogeneous hydrogenation is one of the most investigated and most deeply understood fields of catalysis, and the number of soluble catalysts capable for activating molecular hydrogen is literally countless. The rate of hydrogenation continuously decreased with increasing sterol to phospholipid ratio both with stigmasterol and cholesterol.