Understanding the Effects of Ligand Configuration on Protoporphyrinogen IX Oxidase with Rationally Designed 3‑(N‑Phenyluracil)but-2-enoates

• Published in: Journal of agricultural and food chemistry 2024-04, Vol.72 (15), p.8401-8414
• Main Authors: Yang, Huang-Ze, Liu, Hong-Yun, Li, Sang-Hong, Wang, Da-Wei, Xi, Zhen
• Format: Article
• Language: English
• Subjects: Agricultural and Environmental Chemistry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.3c08483

Protoporphyrinogen IX oxidase (PPO, EC 1.3.3.4) is a promising target for green herbicide discovery. However, the ligand configuration effects on PPO activity were still poorly understood. Herein, we designed 3-(N-phenyluracil)­but-2-enoates using our previously developed active fragments exchange and link (AFEL) approach and synthesized a series of novel compounds with nanomolar ranges of Nicotiana tabacum PPO (NtPPO) inhibitory potency and promising herbicidal potency. Our systematic structure–activity relationship investigations showed that the E isomers of 3-(N-phenyluracil)­but-2-enoates displayed improved bioactivity than their corresponding Z isomers. Using molecular simulation studies, we found that the E isomers showed a relatively lower entropy change and could sample more stable binding conformation to the receptor than the Z isomers. Our density functional theory (DFT) calculations showed that the E isomers showed higher chemical reactivity and lower electronic chemical potential than their corresponding Z isomers. Compound E-Ic emerged as the optimal compound with a K i value of 3.0 nM against NtPPO, exhibiting a broader spectrum of weed control than saflufenacil at 37.5–75 g ai/ha and also safe to maize at 75 g ai/ha, which could be considered as a promising lead herbicide for further development.