Synthesis and antifungal evaluation of a series of maleimides

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.

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.

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