Design, synthesis, antifungal activity, and 3D-QSAR of coumarin derivatives

In our research, a series of 8-substituted coumarin derivatives were synthesized, and their structures were confirmed by FT-IR, ¹H-NMR, and MS (or HRMS). In activity screening, the synthesized compounds exhibited potent antifungal activity against 4 phytopathogenic fungi: Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium oxysporum, and Valsa mali. Notably, 8-chloro coumarin and ethyl 8-chloro-coumarin-3-carboxylate showed the strongest fungus inhibition with EC₅₀ of 0.085 and 0.078 mmol/L against V. mali. Furthermore, 3D-QSAR models (CoMFA and CoMSIA) of the title compounds against V. mali were established on the basis of their antifungal activities. The results indicated that the appropriate small, hydrophilic and electron-withdrawing groups on coumarin's C-3 and C-8, respectively, could enhance the antifungal activity. The information obtained will be very helpful for designing new derivatives with high antifungal activities.