Cytokinin Activity of Benzoylaminodeazapurines, Pentanoylaminodeazapurines and their Corresponding Purine Analogs in Five Bioassays

Abstract

Cytokinin activities of 6‐benzoylamino‐1, 6‐benzoylamino‐3‐, 6‐pentanoylamino‐1‐ and 6‐pentanoylamino‐3‐deazapurines and their corresponding purine analogs, 6‐benzoylaminopurine and 6‐pentanoylaminopurine, were examined using five bioassay systems, tobacco callus growth, bud formation on tobacco callus, lettuce seed germination, fresh weight increase of radish cotyledons and retardation of chlorophyll degradation in radish cotyledons. 6‐Benzoylamino‐ and 6‐pentanoylamino‐1‐deazapurines showed stronger cytokinin activity than their corresponding purine analogs in all bioassays used. In tobacco callus growth, 6‐benzoylamino‐1‐deazapurine was nearly as active as zeatin, one of the most active adenylate cytokinins. On the other hand, 6‐benzoylamino‐ and 6‐pentanoylamino‐3‐deazapurines were as active as or less active than corresponding purine analogs.

Synthesis and Cytokinin Activity of Fluorescent 7-Phenylethynylimidazo[4,5-b]pyridine and Its Riboside

“…A minute structural change caused striking effects. The displacement of the nitrogen atom at the 1-position of 5 with a methine group resulted in about 35-fold enhancement in the activity, in accordance with the results of N 6 -benzoyl-1-dezapurine (Matsubara et al, 1978). More significantly, similar displacement of the riboside 4 led to approximately a 70-fold increase in the activity.…”

“…derivatives have been rarely known until now. Early studies of N 6 -alkyl (De Roos and Salemink, 1971;Rogozinska et al, 1973;Kroon et al, 1974;Kitano et al, 1975) and N 6 -acyl (Sugiyama et al, 1975;Matsubara et al, 1978) derivatives of deazaadenines revealed that, among the deazapurine isomers, only imidazo[4,5-b]pyridines retained high activity. Thus, in the development of new fluorescent cytokinin analogues, we synthesized 7-phenylethynylimizado[4,5-b]pyridine (11) and its riboside 10 by a rational drug design in which they could be endowed with both fluorescence and potent cytokinin activity by transformation without ring expansion.…”

Dose responses of cytokinins

“…For certain cytokinin analogs, responses ranging from ultrasensitive (Spp/Sjo = 7-13) to approximately hyperbolic have been obtained ( Fig. 6 in Matsubara et al 1978 >170 3400 83000* >21000 2500* >3400 270/1700 120-620 4.3x10"' 4.7xlO""/3.6xlO"« 4.5x10 ' 2,5x10"" 6.0x10"" _ -…”