Antibacterial and anti-biofilm activity of quinazolinone derived Schiff base and its Cu(II) complex

According to the last WHO report, the level of bacterial resistance is alarming all over the world. Drug resistant diseases cause at least 700 000 deaths a year [1]. The synthesis of new antibacterial compounds is an important step to overcome this problem. Shiff bases are a privileged structure possessing a wide spectrum of pharmacological activities such as anticancer, antioxidant and antibacterial [2]. The synthesis of 3‑[(2‑hydroxy‑5‑nitrobenzylidene)amino]‑2‑(2‑hydroxy‑5‑nitrophenyl)‑2,3‑dihydroquinazolin‑4(1H)‑one was described, and its spectral analysis, antioxidant and cytotoxic activities were presented [3]. The aim of this work was to study the antibacterial activity of this compound and its Cu(II) complex [4] against a spectrum of bacterial strains as well as the eradication activity against S. aureus biofilm. The compounds showed moderate antibacterial activity, which was slightly higher in the case of Cu(II) complex. The dynamics of activity against S. aureus was analyzed using the time-kill curve method, and the activity was considered as bacteriostatic. Minimum biofilm eradication activity (MBEC90) against staphylococcal biofilm was only twofold higher than MIC against planktonic cells, which shows a great potential of these derivatives as anti-biofilm active drugs. This study was supported by the Ministry of Education of the Czech Republic (LO1305) and by project VEGA 2/0022/18. References: No time to wait–securing the future from drug-resistant infections. Report to the Secretary General of the Nations, 2019, https://www.who.int/docs/default-source/documents/no-time-to-wait-securing-the-future-from-drug-resistant-infections-en.pdf?sfvrsn=5b424d7_6. Sztanke, K.; Maziarka, A.; Osinka, A.; Sztanke, M. An insight into synthetic Schiff bases revealing antiproliferative activities in vitro. Med. Chem. 2013, 21(13):2648–3666. Hricoviniova, Z. Hricovini, M.; Kozics, K. New series of quinazolinone derived Schiff’s bases: synthesis, spectroscopic properties and evaluation of their antioxidant and cytotoxic activity. Pap. 2018, 72(4): 1041–1053. Hricoviniova, Z. et al. manuscript in preparation