Transketolase (TKL) plays a key role in plant photosynthesis and has been predicted to be a potent herbicide target. Homology modeling and molecular dynamics simulation were used to construct a target protein model. A target-based virtual screening was developed to discover novel potential transketolase inhibitors. Based on the receptor transketolase 1 and a target-based virtual screening combined with structural similarity, six new compounds were selected from the ZINC database. Among the structural leads, a new compound ZINC12007063 was identified as a novel inhibitor of weeds. Two novel series of carboxylic amide derivatives were synthesized, and their structures were rationally identified by NMR and HRMS. Biological evaluation of the herbicidal and antifungal activities indicated that the compounds 4u and 8h were the most potent herbicidal agents, and they also showed potent fungicidal activity with a relatively broad-spectrum. ZINC12007063 was identified as a lead compound of potential transketolase inhibitors, 4u and 8h which has the herbicidal and antifungal activities were synthesized based on ZINC12007063. This study lays a foundation for the discovery of new pesticides.

Protoporphyrinogen oxidase (PPO) has been identified as one of the most promising targets for herbicide discovery. A series of novel phthalimide derivatives were designed by molecular docking studies targeting the crystal structure of mitochondrial PPO from tobacco (mtPPO, PDB: 1SEZ) by using Flumioxazin as a lead, after which the derivatives were synthesized and characterized, and their herbicidal activities were subsequently evaluated. The herbicidal bioassay results showed that compounds such as 3a (2-(4-bromo-2,6-difluorophenyl) isoindoline-1,3-dione), 3d (methyl 2-(4-chloro-1,3-dioxoisoindolin-2-yl)-5-fluorobenzoate), 3g (4-chloro-2-(5-methylisoxazol-3-yl) isoindoline-1,3-dione), 3j (4-chloro-2-(thiophen-2-ylmethyl) isoindoline-1,3-dione) and 3r (2-(4-bromo-2,6-difluorophenyl)-4-fluoroisoindoline-1,3-dione) had good herbicidal activities; among them, 3a showed excellent herbicidal efficacy against A. retroflexus and B. campestris via the small cup method and via pre-emergence and post-emergence spray treatments. The efficacy was comparable to that of the commercial herbicides Flumioxazin, Atrazine, and Chlortoluron. Further, the enzyme activity assay results suggest that the mode of action of compound 3a involves the inhibition of the PPO enzyme, and 3a showed better inhibitory activity against PPO than did Flumioxazin. These results indicate that our molecular design strategy contributes to the development of novel promising PPO inhibitors.

α-terthienyl is a natural phytotoxin isolated originally from Flaveria bidentis (L.) Kuntze. The bioassay presented here shows the strong herbicidal activity of α-terthienyl on Digitaria sanguinalis, Arabidopsis thaliana and Chlamydomonas reinhardtii. The α-terthienyl-induced response of A. thaliana at the protein level was analyzed at different times. Changes in the protein expression profiles were analyzed by two-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry (LC-MS/MS) mass spectrometry. Sixteen protein spots were identified that showed reproducible changes in the expression of at least 2-fold when compared to the control. Among these 16 spots, three were up-regulated and 13 were down-regulated. The decreased expression of several proteins associated with energy production and carbon metabolism suggested that these processes were affected by α-terthienyl. To search for the candidate proteins in this screen, A. thaliana T-DNA mutants of the candidate proteins were used to test their susceptibility to α-terthienyl. Amongst the others, attkl1, a mutant of transketolase, exhibited a significantly lower sensitivity to α-terthienyl when hit compared with Col-0. Based on the identification of the proteins associated with the response to α-terthienyl by proteomics, a candidate target protein transketolase was identified.