An experimental approach to evaluation of the relative hydrophobic character of biological liquids and tissues

Total proteins extractable from a number of rat tissues were partitioned in the aqueous Ficoll-400-Dextran-70 biphasic system. The partition coefficient of the total proteins extractable from a given tissue, K, was shown to be a tissue-specific constant. The free energy of transfer of a CH2 group from water to the aqueous solution of a given protein extract, delta(delta gCH2), was calculated from the corresponding K-value using the correlation relationship between K and delta(delta gCH2) reported earlier. It is suggested to use the parameter delta(delta gCH2)-value as a measure of the relative hydrophobic character of biological fluids and tissues. The difference between the delta(delta gCH2)-values for blood plasma medium and for a given tissue medium is used to quantify the difference in the relative hydrophobic character of the biological tissues and fluids under study. The possibilities to use the above characteristics in drug research are considered.