Photosynthetic electron transport inhibition by pholorophenone derivatives.

The structure/activity relationships of phlorophenone derivatives including grandinol and homograndinol, which are potent inhibitors of photosynthetic electron transport (PET) in Eucalyptus grandis, were examined. The results indicate that at least one acyl functionality on a phloroglucinol nucleus was essential for PET inhibition, and that the lipophilicity and/or length of the acyl group was the most prominent factor affecting the activity. In addition, the introduction of a formyl group to monoacylphloroglucinols remarkably enhanced the activity. The structural requirements for PET inhibition in these compounds were found to be very similar but not identical with those for the phenol type of inhibitors proposed by Trebst et al.