Abstract
The present experiments were undertaken in the attempt to throw some light on the mechanism whereby certain water soluble dyes such as rose bengal, when injected intravenously into animals, pass through the liver and are excreted in the bile. 1 Rose bengal in particular, on account of this property, has come into use as a test for liver function. 2 The experiments of Wieland and Sorge 3 and others 4 showing that deoxycholic acid combines with fatty acids, xylol, phenol, camphor, naphthaline, cholesterol and related substances to form the corresponding choleic acid and that excretion of the conjugated compound via the bile constitutes a method whereby the detoxicated product is eliminated, suggested that rose bengal might also combine with deoxycholic acid. The preparation of the rose bengal-deoxycholic acid complex was therefore undertaken.
Varying quantities of rose bengal were heated for several hours under a reflux condenser with known amounts of an alcoholic solution of deoxycholic acid (250 mg. of deoxycholic acid dissolved in 5-10 cc. of alcohol), an excess of dye always being present. The mixture was then concentrated in vacuo until a semi-viscous fluid was obtained. The presence of deoxycholic acid increases the solubility of the dye in alcohol. On addition of water the deoxycholic acid-dye compound was precipitated and the excess of dye was removed by repeatedly washing with water. The compound was recrystalized several times from alcohol containing a little rose bengal by addition of water. The excess of dye was removed by washing with water. The amount of dye contained in the complex was estimated colorimetrically by comparison with a standard solution of rose bengal containing 1 mg. in 10 cc. of alcohol. The dye could be dissociated from the compound by boiling with xylol.
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