Discovery of Pyrroloquinazoline-1,3-diamines as Dual-function Insecticide Candidates Targeting β-N-acetyl-D-hexosaminidase.

Background: β-N-acetyl-D-hexosaminidase (Hex) plays crucial roles in insect growth and development, as well as in cell proliferation and pathogen invasion in fungi. The discovery of inhibitors targeting Hexs holds great promise for the development of eco-friendly agrochemicals.

Methods: Novel inhibitors of insect Hex from Ostrinia furnacalis (OfHex1) were identified through enzymatic assays. Molecular docking was employed to elucidate the binding mechanisms of the inhibitors. The biological activities of identified inhibitors were assessed in vivo and in vitro by administration of the compounds to the 3rd instar larvae of Ostrinia furnacalis and the agricultural pathogen Fusarium graminearum, respectively.

Results: Pyrroloquinazoline-1,3-diamines (PQDs) were identified as competitive inhibitors of OfHex1 at the micromolar level. Through hydrogen bonding and hydrophobic interactions, PQDs were bound within the active sites of OfHex1. The most potent compound, designated as 4h, demonstrated an insecticidal efficacy of 86.7% against the 3rd instar larvae of O. furnacalis when administered at 2 mM. Additionally, 4a displayed complete inhibition of mycelium spreading at 1 mM.

Conclusion: PQDs exhibited significant inhibitory activity against OfHex1 and demonstrated substantial insecticidal and fungicidal potency, positioning PQDs as promising candidates for the development of dual-function insecticide candidates.