Abstract
Due to the lack of dependable methods for their identification, the isolation of nucleinic compounds from biological fluids is not an easy matter. Among the precipitants which might be useful in the isolation of these substances, flavianic acid (1-naphthol-2-4-dinitro-7-sulfonic acid) seemed to be promising. Kossel and Gross 1 found that flavianic acid forms crystalline compounds with organic bases. Among other substances these workers prepared guanine flavianate.
We have prepared the flavianates of cystosine, 5-methylcystosine, 2-amino-4-methyluracil, guanosine, adenosine and cytidine.
It has been found (with O. H. Emerson) that cytidine flavianate is a very useful substance in the isolation of cytidine from yeast nucleic acid. Flavianic acid is more satisfactory than picric acid for decomposing cytidine nitrate. Although cytidine flavianate does not seem to crystallize from an impure solution, it forms beautiful crystals when fairly pure and is a very convenient substance for recrystallizing as it has a very high temperature gradient of solubility. The flavianate is easily decomposed by dissolving it in 5% sulfuric acid at 60° and extracting the flavianic acid with butyl alcohol from the warm solution. The cytidine sulfate obtained from the flavianate was extremely pure, and one recrystallization proved sufficient to obtain the base in beautiful crystals.
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