Identification of novel 4-substituted 7H-pyrrolo[2,3-d]pyrimidine derivatives as new FtsZ inhibitors: Bioactivity evaluation and computational simulation.

Bacterial infections and the consequent outburst of bactericide-resistance issues are fatal menace to both global health and agricultural produce. Hence, it is crucial to explore candidate bactericides with new mechanisms of action. The filamenting temperature-sensitive mutant Z (FtsZ) protein has been recognized as a new promising and effective target for new bactericide discovery. Hence, using a scaffold-hopping strategy, we designed new 7H-pyrrolo[2,3-d]pyrimidine derivatives, evaluated their antibacterial activities, and investigated their structure-activity relationships. Among them, compound B exhibited the optimal in vitro bioactivity (EC = 4.65 µg/mL) against Xanthomonas oryzae pv. oryzae (Xoo), which was superior to the references (bismerthiazol [BT], EC = 48.67 µg/mL; thiodiazole copper [TC], EC = 98.57 µg/mL]. Furthermore, the potency of compound B in targeting FtsZ was validated by GTPase activity assay, FtsZ self-assembly observation, fluorescence titration, Fourier-transform infrared spectroscopy (FT-IR) assay, molecular dynamics simulations, and morphological observation. The GTPase activity assay showed that the final IC value of compound B against XooFtsZ was 235.0 μM. Interestingly, the GTPase activity results indicated that the B-XooFtsZ complex has an excellent binding constant (K = 10 M). Overall, the antibacterial behavior suggests that B can interact with XooFtsZ and inhibit its GTPase activity, leading to bacterial cell elongation and even death. In addition, compound B showed acceptable anti-Xoo activity in vivo and low toxicity, and also demonstrated a favorable pharmacokinetic profile predicted by ADMET analysis. Our findings provide new chemotypes for the development of FtsZ inhibitors as well as insights into their underlying mechanisms of action.