Cytokinins: identification of compounds isolated from Corynebacterium fascians.

Abstract

KlAmbt, Thies, and Skoog' have described the isolation and the biological effects on tobacco tissue cultures of several organic bases, obtained as their picrates, from large-scale batches of Corynebacterium fascians.In a cooperative effort with the Wisconsin workers, we have been able to identify these substances, by spectrometric means and by comparison with authentic samples, as the picrates of 6-(yy-dimethylallylamino)purine (designated as II), nicotinamide (III, IV), and 6-methyl- aminopurine (V).The activity of the first of these compounds in promoting callus growth had previously been shown to be an order greater than that of kinetin.2Characterization.-6-('y,-y-Dimethylallylamino)purine (II): The sample furnished for characterization consisted of 1.7 mg of a bright yellow solid, mp 216-218'.3Recrystallization from absolute ethanol yielded fine needles, mp 221-223°.Inser- tion of the picrate sample into the ionizing beam gave a mass spectrum which showed abundant ions, neglecting those due to the picric acid moiety, at m/e 203, 188, 160, 148, 135, 119, and 108.It was noted that the mass spectra of other picrates pre- pared for comparison4 clearly indicated the molecular ions for picric acid (229) and, in each case, for the ion of the associated base.This finding, which qualifies for more general application, permitted the conclusion that the molecular weight of the basic component of the picrate was 203.The ultraviolet spectra of II(picrate) showed absorption maxima in the 260- 280-mu region which are not present in the spectra of picric acid taken under the same conditions.A portion of recrystallized picrate was dissolved in ethanol and treated with Dowex-1-HCO3-m When the resin was removed by filtration, the colorless filtrate showed the following ultraviolet maxima: XmaxEtOH 269, 210 my;