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

Bacterial leaf blight (BLB) and bacterial leaf streak
(BLS) are
two serious bacterial diseases caused by Xanthomonas
oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), 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 E35 designed based on the 3D-QSAR model
was demonstrated as the optimal in vitro activity
against Xoo and Xoc, 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 E35 had
superior protective activity (43.7%) on BLS to thiodiazole copper
(32.1%). The defense enzymes and proteomics results suggested that
compound E35 could be a versatile candidate as it improved
plant’s resistance to disease.