Nain-Perez Amalyn, Barbosa Luiz C A, Maltha Celia R A, Giberti Samuele, Forlani Giuseppe
Department of Chemistry, Universidade Federal de Minas Gerais , Av. Pres. Antônio Carlos, 6627, Campus Pampulha, CEP 31270-901, Belo Horizonte, MG Brazil.
Department of Chemistry, Universidade Federal de Viçosa , Viçosa, Av. P. H. Rolfs s/n, CEP 36570-000, Viçosa, MG Brazil.
J Agric Food Chem. 2017 Dec 27;65(51):11304-11311. doi: 10.1021/acs.jafc.7b04624. Epub 2017 Dec 13.
Abenquines are natural N-acetylaminobenzoquinones bearing amino acid residues, which act as weak inhibitors of the photosynthetic electron transport chain. Aiming to exploit the abenquine scaffold as a model for the synthesis of new herbicides targeting photosynthesis, 14 new analogues were prepared by replacing the amino acid residue with benzylamines and the acetyl with different acyl groups. The synthesis was accomplished in three steps with a 68-95% overall yield from readily available 2,5-dimethoxyaniline, acyl chlorides, and benzyl amines. Key steps include (i) acylation of the aniline, (ii) oxidation, and (iii) oxidative addition of the benzylamino moiety. The compounds were assayed for their activity as Hill inhibitors, under basal, uncoupled, or phosphorylating conditions, or excluding photosystem I. Four analogues showed high effectiveness (IC = 0.1-0.4 μM), comparable with the commercial herbicide diuron (IC = 0.3 μM). The data suggest that this class of compounds interfere at the reducing side of photosystem II, having protein D1 as the most probable target. Molecular docking studies with the plastoquinone binding site of Spinacia oleracea further strengthened this proposal.
阿本喹类化合物是带有氨基酸残基的天然N - 乙酰氨基苯醌，它们作为光合电子传递链的弱抑制剂。旨在利用阿本喹骨架作为合成靶向光合作用的新型除草剂的模型，通过用苄胺取代氨基酸残基以及用不同的酰基取代乙酰基制备了14种新类似物。该合成以三步完成，从容易获得的2,5 - 二甲氧基苯胺、酰氯和苄胺出发，总产率为68 - 95%。关键步骤包括：（i）苯胺的酰化，（ii）氧化，以及（iii）苄氨基部分的氧化加成。在基础、解偶联或磷酸化条件下，或者排除光系统I的情况下，对这些化合物作为希尔抑制剂的活性进行了测定。四种类似物显示出高效性（IC = 0.1 - 0.4 μM），与商业除草剂敌草隆（IC = 0.3 μM）相当。数据表明这类化合物在光系统II的还原侧起作用，最可能的靶标是蛋白质D1。用菠菜的质体醌结合位点进行的分子对接研究进一步支持了这一观点。
