Design, Synthesis, Antibacterial Activity, Antiviral Activity, and Mechanism of Myricetin Derivatives Containing a Quinazolinone Moiety

Abstract

Plant bacteria such as <i>Xanthomonas axonopodis</i> <i>pv. citri</i> (<i>Xac</i>), <i>Pseudomonas syringae</i> <i>pv. actinidiae</i> (<i>Psa</i>), <i>Xanthomonas oryzae</i> <i>pv. oryzae</i> (<i>Xoo</i>), and tobacco mosaic virus (TMV) have created huge obstacles to the global trade of food and economic crops. However, traditional chemical agents used to control these plant diseases have gradually become disadvantageous due to long-term irregular use. Therefore, finding new and efficient antibacterial and antiviral agents is becoming imperative. In this study, a series of myricetin derivatives containing a quinazolinone moiety were designed and synthesized, and the antibacterial and antiviral activities of these compounds were evaluated. The bioassay results showed that some target compounds exhibited good antibacterial activities <i>in vitro</i> and antiviral activities <i>in vivo</i>. Among them, the median effective concentration (EC₅₀) value of compound <b>L18</b> against <i>Xac</i> was 16.9 μg/mL, which was better than those of the control drugs bismerthiazol (BT) (62.2 μg/mL) and thiodiazole copper (TC) (97.5 μg/mL). Scanning electron microscopy (SEM) results confirmed that compound <b>L18</b> inhibited the growth of <i>Xac</i> by affecting the morphology of cells. Microscale thermophoresis (MST) test results indicated that the dissociation constant (<i>K</i> _d) value of compound <b>L11</b> against TMV-CP was 0.012 μM, which was better than that of the control agent ningnanmycin (2.726 μM). This study reveals that myricetin derivatives containing a quinazolinone moiety are potential antibacterial and antiviral agents.