Effects of Coumarinyl Schiff Bases against Phytopathogenic Fungi, the Soil-Beneficial Bacteria and Entomopathogenic Nematodes: Deeper Insight into the Mechanism of Action.

Coumarin derivatives have been reported as strong antifungal agents against various phytopathogenic fungi. In this study, inhibitory effects of nine coumarinyl Schiff bases were evaluated against the plant pathogenic fungi ( f. sp. , , and ). The compounds were demonstrated to be efficient antifungal agents against . The results of molecular docking on the six enzymes related to the antifungal activity suggested that the tested compounds act against plant pathogenic fungi, inhibiting plant cell-wall-degrading enzymes such as endoglucanase I and pectinase. Neither compound exhibited inhibitory effects against two beneficial bacteria ( and ) and two entomopathogenic nematodes. However, compound was lethal (46.25%) for nematode and showed an inhibitory effect against acetylcholinesterase (AChE) (31.45%), confirming the relationship between these two activities. Calculated toxicity and the pesticide-likeness study showed that compound was the least lipophilic compound with the highest aquatic toxicity. A molecular docking study showed that compounds and bind directly to the active site of AChE. Coumarinyl Schiff bases are promising active components of plant protection products, safe for the environment, human health, and nontarget organisms.