Abstract
Sparing solubility of this substance in alcohol. Extraction experiments with 80% alcohol were deemed of special interest because of the use of such alcohol extracts by Goldberger and associates 1 and because alcohol of almost the same concentration (79%) had been used by Osborne and Wakeman 2 for the precipitation of their “fraction II” which contained a relatively high concentration of both of the recently differentiated water-soluble factors required in the growth of rats.
In the present experiments, 400 gm. of air-dry baker's yeast were treated with 1500 cc. of alcohol (80% by weight), thoroughly stirred, and allowed to stand at room temperature (20°-25° C.) for 24 hours; then filtered with suction, and the yeast washed on a Büchner filter with 750 cc. of alcohol of the same strength; then again stirred with 1500 cc. of the alcohol, allowed to stand 24 hours, filtered and washed as before. The residue was dried in the air at room temperature.
The extract obtained by combining the 2 filtrates and the washings was a clear yellow solution of pH 6.1. It was concentrated on the steam bath and evaporated at room temperature on cornstarch. Feeding experiments indicated that this extract contained the greater part of the antineuritic vitamin but scarcely measurable amounts of the heat-stable factor. The extracted residue, however, was somewhat less potent than the original yeast as a source of this latter factor.
Extraction as above with alcohol 60% (by weight) gave a greenish yellow-brown solution of pH 5.9, which frothed easily. Feeding experiment with the extracted residue indicated that it retained about one-half of the heat-stable factor of the dry yeast. The evaporated extract, while showing decided activity, seemed less potent than the extracted residue.
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