Biological activity of several 9-nonglycosidic-substituted natural cytokinins

Abstract

Abstract.A series of 9-substituted derivatives of four common naturally occurring cytokinins was tested for growth response in the soybean callus assay. The 9-substituents, 2-carboxyethyl (-C2CO2H), 2-carbo-t-butoxyethyl (-C2CO2tBu), and 2-nitriloethyl (-C2CN), all reduced the biological activity of the parent compound. The order of activities was, in general, -C2CO2 H > -C2CO2tBu > -C2CN and followed the unsubstituted cytokinin response pattern ofThe nature of the dose-response curves indicate that the activities of the derivatives are a function of their affinities to a common receptor site and that their steric and polar properties determine that affinity.The 9-(2-carboxyethyl) cytokinins provide a practical alternate source of haptens for the raising of cytokinin antibodies, since sugar-cleavage oxidations are avoided in the preparation of the antigens. E-9-(2-carboxyethyl)-O-13-D-glucopyranosylzeatin (E-ZOG9C2CO2H) was synthesized for the purpose of making antibodies specific for E-O-13-D-glucopyranosylzeatin (E-ZOG) and was also assayed for its growth response.The results obtained with stable 9-substituted cytokinins are useful in defining guidelines for the design of ligands available to explore receptorsite topology.Structure-activity studies for small organic molecules have been very reWarding in a number of fieldsmmedicine, pesticide research, and the study of Reference to a company and/or product named by the Department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others Which may also be suitable.

New cytokinin metabolites in IPT transgenic Arabidopsis thaliana plants

“…A volume of 85 µl of 93% hydrazin hydrate was added to a solution containing 178 mg (0.317 mmol) ( E )‐2‐methyl‐4‐phthalimidolbut‐2‐enyl‐2,3,4,6‐tetra‐ O ‐acetyl‐ β ‐ d ‐glucopyranoside (1c) (Corse et al 1989) in 2 ml of ethanol, and the solution was maintained at room temperature and stirred for 1 day. Fresh hydrazin hydrate (17 µl) was then added and stirring continued for a further day.…”

Naturally Occurring and Artificial N9-Cytokinin Conjugates: From Synthesis to Biological Activity and Back

“…A number of non-sugar 9-substituted derivatives of CKs have been described, several of which occur naturally and were discovered in plant tissues, such as 9-alanyl derivatives [ 7 ]. Most non-sugar 9-substituted CKs have been prepared as mimetics of CK sugar conjugates in the laboratory conditions [ 66 , 144 , 145 , 146 , 147 ]. We summarize current knowledge of these non-sugar 9-substituted CK derivatives and their biological activity in the following sections.…”

“…Subsequently, series of 9-substituted ethyl derivatives of four naturally occurring CKs ( t Z, c Z, DHZ, iP Figure 10 ) were synthesized [ 146 ]. All of these derivatives were less active than the parent CKs in the soybean callus bioassay and their relative activities were more dependent on the structure of the isoprenoid side chain.…”

“…All of these derivatives were less active than the parent CKs in the soybean callus bioassay and their relative activities were more dependent on the structure of the isoprenoid side chain. The results clearly showed the importance of the structure and size of N9 substitutions and indicated that steric effects cause much lower losses of biological activity than the polarity of the substituent functional groups [ 146 ].…”

“…On N6 (R1): tZ, cZ, DHZ, and iP side chains. On N9 (R2): 2-carboxyethyl, 2-carbo- t -butoxyethyl and 2-nitriloethyl) [ 146 ].…”