We studied the interaction with liposomes and the antioxidant activity of flavonoid (quercetin, catechin, taxifolin) complexes with iron (III). It was found that the lipophilicity of complexes depends on an iron:flavonoid ratio and grows at a ratio of 1 to 1, while complexes in a 2:1 ratio were the most effective to slow down the lipid peroxidation and restore radical 2,2-diphenyl-1-pic: rylhydrazyl. Thus, the stoichiometry of complexes formed in aqueous solution, may differ from the stoichiometry of complexes that most effectively protect membranes from.peroxidation.

Differential scanning calorimetry was used to study the influence of the flavonoid taxifolin (dihydroquercetin) on the temperature-dependent phase transition of dimyristoylphosphatidylcholine multilamellar liposomes. Taxifolin was added to organic solution of the lipid during the procedure of liposomes preparation (addition from-within) or to a suspension of prepared liposomes (addition from-without). In the first case, liposomes contained from 2 to 50 mol% of taxifolin added from-within; in the second case, lyposomes were treated with 0.001% or 0.01% taxifolin. In both cases, the effect was similar. When the concentration of taxifolin increased, the temperature of lipid melting decreased while the width of transition considerably enlarged. Freeze-fracture electron microscopy revealed that taxifolin did not rupture multilamellar liposomes, while the formation of ripple-phase was retarded in all bilayers even when the liposomes were treated from without. This suggested the ability of taxifolin to penetrate through numerous bilayers of multilamellar liposomes.

Intravenous administration of emulsions of some perfluorochemicals (PFCs) are followed by lung gas-exchange alterations, lung inflation and animal death. The emulsion toxicity can be caused by both low aggregation stability of the emulsion in the blood stream and appearance of the additional gas pressure in alveoli as a result of difference in the rates of alveolar gas and PFC vapor diffusion. Theoretical and experimental analysis shows that (1) absence of emulsion particle aggregation into blood stream, (2) low pressure of saturated vapors of PFC phase and (3) relatively low rate of PFC expiration from the organism are essential conditions for the creation of a safe fluorocarbon blood substitutes.

Treatment of membranes of rat liver microsomal ghosts in a homogenizer with a Teflon pestle results in fragments strongly differing in their protein--lipid ratios. The fragments obtained can be separated by ultracentrifugation in sucrose density gradient into light and heavy fractions. The light fraction contains predominantly phospholipid vesicles devoid of intramembrane particles on the hydrophobic surfaces of the membrane. The heavy fraction is represented by proteolipid complexes which contain all proteins typical for original ghost membranes and are enriched with neutral lipids. The proteolipid complexes appear as globular particles of the same diameter as the intramembrane particles of microsomal ghosts. It is assumed that the intramembrane particles of microsomes are represented by large polyenzyme proteolipid complexes rather than by individual proteins. The former can be isolated in a pure state.

Freeze-fracture electron microscopy has been used to study the ultrastructure of proteolytic enzymes treated of the bovine photoreceptor membranes, the rat liver microsome ghosts and the rabbit sarcoplasmic reticulum membranes. The observed increase in the intramembranous particle number in the inner fracture face suggests transmembrane dipping of amphipathic integral proteins affected by the partial proteolysis.

The dependence of the state of the hydrophobic zone of rabbit sarcoplasmic reticulum (SR) membranes on temperature of the membrane fragment suspension before rapid freezing was studied by the freeze fracturing technique. It was shown that within the temperature range of--15-- +37 degrees C the amount of intramembrane particles and their distribution in the membrane plane and between their convex and concave surfaces do not practically depend on the temperature of the SR membrane suspension. This is indicative of the lack of correlation between the physical state of the phospholipid matrix (gel -- liquid crystal) before freezing and the nature of the profile of the membrane hydrophobic zone revealed after fracturing. The disturbances in the protein -- lipid interactions in the membrane under the effects of mersalyl or aqueous solutions of diethyl ester followed by complete inactivation of Ca2+-dependent ATPase lead to a decrease in the amount of intramembrane particles, which is especially well-pronounced at 37 degrees and -15 degrees C.