Synthesis and Biological Evaluations of a Series of Thaxtomin Analogues

• Published in: Journal of agricultural and food chemistry 2015-04, Vol.63 (14), p.3734-3741
• Main Authors: 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
• Format: Article
• Language: English
• Subjects: Herbicides - chemical synthesis; Herbicides - chemistry; Herbicides - pharmacology; Indoles - chemical synthesis; Indoles - chemistry; Indoles - pharmacology; Molecular Structure; Piperazines - chemical synthesis; Piperazines - chemistry; Piperazines - pharmacology; Plant Weeds - drug effects; Structure-Activity Relationship; Weed Control
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf506153t

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.