INTERACTIONS BETWEEN ORANGE II AND SELECTED LONG CHAIN QUATERNARY AMMONIUM SALTS

Physicochemical properties of 2′-benzoyloxycinnamaldehyde

2'-Benzoyloxycinnamaldehyde (BCA), a derivative of 2-hydroxycinnamaldehyde demonstrated a potent antitumor effect against several human solid tumor cell lines. The physicochemical properties and degradation kinetics of BCA were investigated to support the drug-development effort. The aqueous solubility of BCA was low, and it was not considered to be hygroscopic. The degradation of BCA followed the first-order kinetics, and the pH-rate profile revealed that the degradation of BCA was governed by general acid- and specific base-catalysis as well as spontaneous hydrolysis. BCA was very unstable in basic conditions, in particular pH above 9, and found to be more stable in acidic conditions such as pH between 2 and 4. The degradation of BCA was accelerated in elevated temperature and high-ionic strength. Therefore, it was suggested that BCA should be stored in slightly acidic conditions with lowered temperature and ionic strength.

Improved Synthesis of Aza-bis(oxazoline) Ligands

A straightforward synthesis of chiral aza-bis(oxazoline) (Azabox) ligands from commercially available amino alcohols is described. The new protocol allows access to previously reported Azabox ligands in considerably improved yields but also to new derivatives, including non-C2-symmetrical ones.

A study of the physicochemical interactions between biliary lipids and chlorpromazine hydrochloride. Bile-salt precipitation as a mechanism of phenothiazine-induced bile secretory failure

Since chlorpromazine hydrochloride [2-chloro-10-(3-dimethylaminopropyl)-phenothiazine hydrochloride] is commonly implicated in causing bile-secretory failure in man and is secreted into bile, we have studied the physicochemical interactions of the drug with the major components of bile in vitro. Chlorpromazine hydrochloride molecules are amphiphilic by virtue of possessing a polar tertiary amine group linked by a short paraffin chain to a tricyclic hydrophobic part. At pH values below the apparent pK (pK'a 7.4) the molecules are water-soluble cationic detergents. We show that bile salts in concentrations above their critical micellar concentrations are precipitated from solution by chlorpromazine hydrochloride as insoluble 1:1 salt complexes. In the case of mixed bile-salt/phosphatidylcholine micellar solutions, however, the degree of precipitation is inhibited by the phospholipid in proportion to its mole fraction. With increases in the concentration of chlorpromazine hydrochloride or bile salt, micellar solubilization of the precipitated complexes results. Sonicated dispersions of the negatively charged phospholipid phosphatidylserine were also precipitated, but dispersions of the zwitterionic phospholipid phosphatidylcholine were not. Chlorpromazine hydrochloride efficiently solubilized these membrane phospholipids as mixed micellar solutions when the drug:phospholipid molar ratio reached 4:1. Polarizing-microscopy and X-ray-diffraction studies revealed that the precipitated complexes were amorphous and potentiometric studies confirmed the presence of a salt bond. Some dissociation of the complex occurred in the case of the most polar bile salt (Ks 0.365). As canalicular bile-salt secretion determines much of bile-water flow, we propose that complexing and precipitation of bile salts by chlorpromazine hydrochloride and its metabolites may be physicochemically related to the reversible bile-secretory failure produced by this drug.