Structure/Activity Relationships of Grandinol: a Germination Inhibitor in Eucalyptus

Abstract

Structure/activity relationships of grandinol (1), which shows potent inhibition to cress germination, were examined by an activity comparison of many synthetic analogues. The result clearly indicates that a combination of two carbonyl functionalities on a phloroglucinol nucleus is necessary for inhibition. The presumptive site of action requires strict steric limitation of the ketonic side chain, which must be less than four carbon units in length. The alkyl substituent on the nucleus is not essential, although it may enhance the activity.