Abstract

A series of fluorinated 7-hydroxycoumarin derivatives containing an oxime ether moiety have been designed, synthesized and evaluated for their antifungal activity. All the target compounds were determined by 1H-NMR, 13C-NMR, FTIR and HR-MS spectra. The single-crystal structures of compounds 4e, 4h, 5h and 6c were further confirmed using X-ray diffraction. The antifungal activities against Botrytis cinerea (B. cinerea), Alternaria solani (A. solani), Gibberella zeae (G. zeae), Rhizoctorzia solani (R. solani), Colletotrichum orbiculare (C. orbiculare) and Alternaria alternata (A. alternata) were evaluated in vitro. The preliminary bioassays showed that some of the designed compounds displayed the promising antifungal activities against the above tested fungi. Strikingly, the target compounds 5f and 6h exhibited outstanding antifungal activity against B. cinerea at 100 μg/mL, with the corresponding inhibition rates reached 90.1 and 85.0%, which were better than the positive control Osthole (83.6%) and Azoxystrobin (46.5%). The compound 5f was identified as the promising fungicide candidate against B. cinerea with the EC50 values of 5.75 μg/mL, which was obviously better than Osthole (33.20 μg/mL) and Azoxystrobin (64.95 μg/mL). Meanwhile, the compound 5f showed remarkable antifungal activities against R. solani with the EC50 values of 28.96 μg/mL, which was better than Osthole (67.18 μg/mL) and equivalent to Azoxystrobin (21.34 μg/mL). The results provide a significant foundation for the search of novel fluorinated 7-hydroxycoumarin derivatives with good antifungal activity.

Highlights

  • The rapid growth of the world population will be a great challenge to obtain the enough food produced by limited arable lands [1]

  • Fluorinated 7-hydroxycoumarins were synthesized through reported procedures [25]

  • All the target compounds were identified by 1 HNMR, 13 C-NMR, Fourier transform infrared (FTIR) and HR-MS

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Summary

Introduction

The rapid growth of the world population will be a great challenge to obtain the enough food produced by limited arable lands [1]. The phytopathogenic fungi have emerged as the destructive parasites that results inevitably in large reductions in the yields and quality of agricultural products [2], seriously hindering the sustainable development of agriculture [3,4]. Under these circumstances, the rational application of agricultural fungicides has been identified as a most effective way to protect crops and to elevate agriculture yields [5]. The natural coumarins exhibit the noticeable bioactivities including antitumor, anticoagulant, anti-inflammatory, antioxidant, antifungal and antiviral effects [10,11,12].

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