Phytotoxic effects of selected N-benzyl-benzoylhydroxamic acid metallo-oxygenase inhibitors: investigation into mechanism of action
作者:Martin J. Sergeant、Peter J. Harrison、Robert Jenkins、Graham R. Moran、Timothy D. H. Bugg、Andrew J. Thompson
DOI:10.1039/c3nj00491k
日期:——
Treatment of Arabidopsis thaliana with 100 μM hydroxamic acids F1 and F2, found previously to inhibit carotenoid cleavage dioxygenase enzyme CCD1, was found to cause chlorophyll bleaching and phytotoxicity. A further set of hydroxamic acid analogues was synthesised, and these compounds were found to be phytotoxic towards A. thaliana at 16–400 μM, and to show some phytoxicity towards broad-leaved weeds C. album and S. media at 100 μM. Compound F1 was found to inhibit p-hydroxy-phenylpyruvate dioxygenase (HPPD), a known herbicide target (IC50 30 μM), but compounds F5 and F8 showed no inhibition of HPPD, despite F8 showing higher levels of phytotoxicity. Plants grown in the presence of F1 or F5 that were treated with 50 μM homogentisic acid showed partial recovery of growth, indicating some inhibition of HPPD in planta. These are the first hydroxamic acid inhibitors reported for HPPD, but the results indicate that inhibition of HPPD is only partly responsible for the observed phytotoxicity, and that another unknown metalloenzyme is also targeted by these compounds.
以前曾发现 100 μM 的羟肟酸 F1 和 F2 能抑制类胡萝卜素裂解二氧酶 CCD1,用它们处理拟南芥会导致叶绿素漂白和植物毒性。又合成了一组羟肟酸类似物,发现这些化合物在 16-400 μM 的浓度下对 A. thaliana 有植物毒性,在 100 μM 的浓度下对阔叶杂草 C. album 和 S. media 有一定的植物毒性。发现化合物 F1 可抑制对羟基苯丙酮酸二加氧酶(HPPD),这是一种已知的除草剂靶标(IC50 30 μM),但化合物 F5 和 F8 对 HPPD 没有抑制作用,尽管 F8 的植物毒性更高。在 F1 或 F5 存在下生长的植物,经 50 μM 均五味子酸处理后,部分恢复了生长,这表明在植物体内对 HPPD 有一定的抑制作用。这些是首次报道的 HPPD 羟肟酸抑制剂,但研究结果表明,HPPD 的抑制作用只是造成所观察到的植物毒性的部分原因,这些化合物还针对另一种未知的金属酶。