Fungicidal Activity of Novel Quinazolin-6-ylcarboxylates and Mode of Action on Botrytis cinerea.

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Fungal diseases remain important causes of crop failure and economic losses. As the resistance toward current selective fungicides becomes increasingly problematic, it is necessary to develop efficient fungicides with novel chemotypes. A series of novel quinazolin-6-ylcarboxylates which combined the structures of pyridine or heterocyclic motif and the N-(3-chloro-4-fluorophenyl)quinazolin-4-amine moiety, a binding group of ATP-binding site of gefitinib, were evaluated for their fungicidal activity on different phytopathogenic fungi. Most of these compounds showed excellent fungicidal activities against Botrytis cinerea and Exserohilum rostratum, especially compound F17 displayed the highest activity with EC50 values as 3.79 μg/mL against B. cinerea and 2.90 μg/mL against E. rostratum, which was similar to or even better than those of the commercial fungicides, such as pyraclostrobin (EC50 , 3.68, 17.38 μg/mL) and hymexazol (EC50 , 4.56, 2.13 μg/mL). Moreover, compound F17 significantly arrested the lesion expansion of B. cinerea infection on tomato detached leaves and strongly suppressed grey mold disease on tomato seedlings in greenhouse. The abilities of compound F17 to induce cell apoptosis of the non-germinated spores, to limit oxalic acid production, to reduce malate dehydrogenase (MDH) expression, and to block the active pocket of MDH protein were demonstrated in B. cinerea. The novel quinazolin-6-ylcarboxylates containing ATP-binding site-directed moiety, especially compound F17, could be developed as a potential fungicidal candidate for further study. This article is protected by copyright. All rights reserved.