Synthesis, Antibacterial Activity, and Action Mechanism of Novel Sulfonamides Containing Oxyacetal and Pyrimidine

Abstract

Bacterial leaf blight (BLB) and bacterial leaf streak (BLS) are two serious bacterial diseases caused by <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> (<i>Xoo</i>) and <i>Xanthomonas oryzae</i> pv. <i>oryzicola</i> (<i>Xoc</i>), respectively. However, the control of these diseases by conventional pesticides remains challenging due to development of resistances. We aimed to address this pending problem and developed a series of novel pyrimidine sulfonamide derivatives. Structurally, title compounds bear a unique oxyacetal group, which has a proven immune-activating effect. Compound <b>E35</b> designed based on the 3D-QSAR model was demonstrated as the optimal <i>in vitro</i> activity against <i>Xoo</i> and <i>Xoc</i>, with EC₅₀ values of 26.7 and 30.8 mg/L, respectively, which were higher than the positive controls bismerthiazol (29.9 and 32.7 mg/L) and thiodiazole copper (30.5 and 36.4 mg/L). On the prevention level, the biological activity test showed compound <b>E35</b> had superior protective activity (43.7%) on BLS to thiodiazole copper (32.1%). The defense enzymes and proteomics results suggested that compound <b>E35</b> could be a versatile candidate as it improved plant's resistance to disease.