4-Phenylphenalenones as a template for new photodynamic compounds against Mycosphaerella fijiensis.

Background: Evaluation of 4-phenylphenalenones and structural analogues against the fungal pathogen Mycosphaerella fijiensis (causal agent of black sigatoka disease in bananas) under light-controlled conditions uncovered some key structural features for the design of photodynamic compounds.

Results: Structure-activity relationship analysis revealed the importance of a chromophoric aryl-ketone and a steroidomimetic structural motif in the activity of the assayed compounds. The results pointed to 1,2-dihydro-3H-naphtho[2',1':3,4]cyclohepta[1,2-b]furan-3-one, which displayed an activity in the range of propiconazole but with photodynamic behaviour.