Fatty acid ester surfactants Cremophor EL and Solutol H S I 5were described earlier as modulators of multidrug resistance mediated by MDR I P-glycoprotein (Pgp). We have shown that the most active components of these polydisperse surfactants are fatty acid-polyethylene glycol-fatty acid diesters (FA-PEG-FA). A new generation of Pgp-surfactant inhibitors of defined structure was therefore synthesized. In the present study we show that these compounds are also able to inhibit upregulation of MDRI gene expression caused by cytarabine (AM-C) and doxorubicin in human tumor cell lines H9 and KB 3-I, which express minimal levels of MDR I mRNA. The surfactant inhibitors, however, had no effect on the induction of Q 1996 Wiley-Liss, Inc.
Several series of thermotropic liquid-crystalline polyesters, based on Cchlorwarbonyl phenyl esters of aromatic dicarboxylic acids (1 -4) and phenols or aliphatic diols, were synthesized and studied by polarizing microscopy and differential scanning calorimetry (DSC). A relationship between geometry of mesogenic moiety and stability of mesophase formed by the polymers was established. The effect of both the length and chemical structure of the flexible fragments on the mesomorphic properties was revealed for polyesters obtained from aliphatic diols. Several polymers were obtained whose temperatures of transition into the liquid crystalline state were found to be below 100 "C. Two series of low-molecular-weight liquid-crystalline compounds were synthesized to compare their properties with those of the polymers of similar structure. Most of the low-molecular-weight analogs have not been described so far. They predominantly form a smectic type mesophase.
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