Biological activity of 6‐(2,3,4‐trihydroxy‐3‐methylbutylamino)purine, an oxidation product of zeatin

Abstract
6‐(2,3,4‐Trihydroxy‐3‐methylbutylamino)purine was identified as an oxidation product of cis‐zeatin and is biologically as active as the parent compound. A comparison of trans‐zeatin, cis‐zeatin and (±)‐dihydrozeatin indicated that trans‐zeatin and (±)‐dihydrozeatin were more active in the soybean callus bioassay than cis‐zeatin. Both the trans‐ and cis‐isomers of zeatin did, however, give an optimum response at 10‐5M. Dihydrozeatin was more active at concentrations of 10‐6 and 10‐5M than trans‐zeatin. The significance of the formation of 6‐(2,3,4‐trihydroxy‐3‐methylbutylamino)purine with respect to stereochemistry and the oxidation of cytokinins with an unsaturated isopentenyl side chain is discussed.