Zhang Hongbo, Wang Qingpeng, Ning Xin, Hang Hang, Ma Jing, Yang Xiande, Lu Xiaolin, Zhang Jiabao, Li Yonghong, Niu Congwei, Song Haoran, Wang Xin, Wang Peng George
‡College of Pharmacy, §State Key Laboratory of Elemento-organic Chemistry, and ∥Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071, People's Republic of China.
J Agric Food Chem. 2015 Apr 15;63(14):3734-41. doi: 10.1021/jf506153t. Epub 2015 Apr 3.
Thaxtomins are a unique family of phytotoxins with unique 4-nitroindole and diketopiperazine fragments possessing potential herbicidal activities. This work presents the total synthesis of natural product thaxtomin C and its analogues. The extensive structure-activity relationship study screens four effective compounds, including thaxtomin A and thaxtomin C. It is indicated that 4-nitro indole fragment is essential for phytotoxicity, while benzyl and m-hydroxybenzyl substituents on the diketopiperazine ring are favorable for the efficacy. The N-methylations on indole and diketopiperazine show weak influence on the herbicidal activities. The four selected compounds show effective herbicidal activities against Brassica campestris, Amaranthus retroflexus, and Abutilon theophrasti, which are comparable or better than dichlobenil, even at a dosage of 187.5 g ha(-1). Moreover, these four compounds show good crop-selective properties to different crops and exhibit moderate protoporphyrinogen oxidase (PPO) enzyme inhibition. The antifungal results indicate that thaxtomin C displays inhibition to a wide range of fungi.
毒莠定是一类独特的植物毒素家族，具有独特的4-硝基吲哚和二酮哌嗪片段，具有潜在的除草活性。这项工作展示了天然产物毒莠定C及其类似物的全合成。广泛的构效关系研究筛选出了四种有效化合物，包括毒莠定A和毒莠定C。结果表明，4-硝基吲哚片段对植物毒性至关重要，而二酮哌嗪环上的苄基和间羟基苄基取代基有利于药效。吲哚和二酮哌嗪上的N-甲基化对除草活性影响较弱。所选择的这四种化合物对油菜、反枝苋和苘麻表现出有效的除草活性，即使在187.5 g ha(-1)的剂量下，其活性与敌草腈相当或更好。此外，这四种化合物对不同作物表现出良好的作物选择性，并表现出适度的原卟啉原氧化酶（PPO）抑制作用。抗真菌结果表明，毒莠定C对多种真菌具有抑制作用。
