Synthesis and antifungal evaluation of a series of maleimides.

Background: Maleimides, both natural and synthesised, have good biological activities. In a continuous effort to discover new maleimides with good antifungal activities, the authors have synthesised a series of 3,4-dichloro-, 3-methyl and non-substituted maleimides based on previous studies. The compounds were biologically evaluated against the fungal pathogen Sclerotinia sclorotiorum.

Results: Of the 63 compounds evaluated, 25 compounds had interesting inhibitory potency with EC50 < 10 µg mL(-1). N-(3,5-Dichlorophenyl)-3,4-dichloromaleimide (EC50 = 1.11 µg mL(-1)) and N-octyl-3-methylmaleimide (EC50 = 1.01 µg mL(-1)) were more potent than the commercial fungicide dicloran (EC50 = 1.72 µg mL(-1)). The results showed that compounds exhibiting log P values within the range 2.4-3.0 displayed the best results in terms of fungicidal activity, and this seemed, therefore, to be the optimum range for this physicochemical parameter.

Conclusion: The present work demonstrates that some maleimides can be used as potential lead compounds for developing novel antifungal agents against S. sclerotiorum.