Eleven indole derivatives of biological significance were added to an extract of etiolated pea seedlings and the mixture was separated on a column of Sephadex G-15, by the following sequence of eluants: ethylenediamine-acetate, pH 4.2, ethylenediamine-acetate, pH 7.4, distilled water, and a methanol-water gradient. The bulk of plant constituents was eluted before the indolic compounds. Tryptophan and indole-3-acetic and indole-3-carboxylic acids, as well as indole-3carboxaldehyde, emerged in separate peaks. Three further peaks contained mixtures of indolic compounds, easily separable by thin-layer chromatography, i.e.: 1, tryptamine and tryptophol glucoside (2-(indol-3-ylethylj-P-o-glucopyranoside); 2, indole-3-acetamide, indole-3-acetic acid methyl ester, and tryptophol; and 3, indole-3acetonitrile and indole-3-carboxylic acid methyl ester. Detection limits in combined Sephadex and thin-layer chromatographies ranged from 0.1 to 10.0 pg. Estimated recoveries were above 50% for indole-3carboxaldehyde
and above 80% for five other representative compounds. Thus, the described method permits the isolation, from plant extracts, of acidic, neutral, and basic indolic compounds of widely different polarity.
Methods
Chemicals. 2-(Indol-3-ylethyl)-/3-D-glucopyranoside (tryptophol glucoside) was synthesized in this laboratory (9). Indolic com-419