Design, synthesis, and antibacterial activity of novel Schiff base derivatives of quinazolin-4(3H)-one

• Novel 4(3H)-quinazolinones Schiff base analogues were synthesized.
• The synthesized compounds showed good antibacterial activities.
• The EC50 value of 6x was 49.26 μg/mL against tomato bacterial wilt.
• Preliminary SAR was analysed.

Novel imine derivatives of quinazolin-4(3H)-one were designed and synthesized by using aminoethyl moieties to increase the amine bridge of quinazolin-4(3H)-one amine and then introducing various aromatic aldehydes. The target compounds were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR), mass spectrometry (MS), infrared spectroscopy (IR), elemental analysis, and X-ray diffraction crystallography. Bioassay results indicated that some of the compounds showed good to excellent antibacterial activities against tobacco bacterial wilt and tomato bacterial wilt. The 50% effective concentrations (EC50) of the compounds against tobacco and tomato bacterial wilts ranged from 63.73 μg/mL to 201.52 μg/mL and 38.64 μg/mL to 81.39 μg/mL, respectively, which are lower than that the positive control thiodiazole copper (216.70 and 99.80 μg/mL). These results indicated that novel Schiff base derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco and tomato bacterial wilts.

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