New Types of Kinins and their Action on Fruit Tree Species

Abstract

WE have been engaged in work on the effects of some kinetin analogues on various tree species and have found that they have somewhat different biological activity^1,2. Because of the comparatively low solubility of 6-furfurylamino- and 6-benzylaminopurine in water, which complicates the application of these compounds, our interest was directed primarily to the preparation of kinetin derivatives with higher solubility in water. The solubility of kinins can considerably influence their transport and therefore also their practical application. After application of 6-benzylaminopurine-8-¹⁴C into the petioles of leaves of one-year-old apple shoots, the applied kinin was found by autoradiography about 10 cm in the basipetal direction from the point of application whereas kinin transport in the apical direction was negligible^1,2. The most soluble compounds of this type synthesized by us up to now are N-(6-purinyl)-β-phenylalanine and N-(6-purinyl)-α-phenylglycine and the 6-benzylamino-9-glucosylpurine already described^3,4. The first of these had no biological activity. 6-Benzylamino-9-glucosylpurine was about as active as 6-benzylaminopurine, whereas the biological activity of N-(6-purinyl)-α-phenylglycine depended on the type of application. The activity of N-(6-purinyl-α-phenylglycine applied to the bark and bast is more active in stimulating the buds of apple trees from the winter vegetative rest than is 6-benzylaminopurine itself, or 6-benzylaminoglucosylpurine⁵. Fig. 1, where N-(6-purinyl)-α-phenylglycine was applied to every second bud, shows that leaves of considerable size shot from the stimulated buds within 20 days, whereas no change was observed in the unstimulated control buds.