Insight into the Structural Requirements of Protoporphyrino- gen Oxidase Inhibitors： Molecular Docking and CoMFA of Di- phenyl Ether, Isoxazole Phenyl, and Pyrazole Phenyl Ether

Protoporphyrinogen oxidase （PPO, EC 1.3.3.4） is one of the most significant targets for a large family of in- hibitors that may be used as herbicide, bactericide, fungicide, or photosensitizing activator to treat cancer through photodynamic therapy （PDT）. Molecular docking and CoMFA were combined in a multistep framework with the ultimate goal of identifying important factor contributing to the activity of PPO inhibitors. As a continuation of the previous research work on the development of new PPO inhibitors, the bioassay results indicated that good PPO in- hibitors were discovered in all of the three chemical series with ICs0 values ranging from 0.010 to 0.061 pmol·L ^-1. Using the crystal structure of tobacco mitochondrial PPO （mtPPO） as template, all the compounds were docked into the enzyme active site. The docking pose of each compound was subsequently used in a receptor-based alignment, leading to the development of a significant CoMFA model with r^2 value of 0.98 and q^2 （cross validation r^2） value of 0.63. This novel multistep framework gives insight into the and it can be extended to other classes of PPO inhibitors. In be particularly applicable in virtual screening procedures. structural characteristics for the binding of inhibitors, addition, the simplicity of the proposed approach may

Design, Synthesis and Herbicidal Activities of Tetrahydroisoindoline-1,3-dione Derivatives Containing Alkoxycarbonyl Substituted 2-Benzoxazolinone

Several different alkoxycarbonyl-substituted 2-benzoxazolinone moieties have been incorporated into a tetrahy- droisoindoline-1,3-dione scaffold to provide 25 compounds （1a-lu and 2a-2d）. The structures of these compounds were confirmed by 1H and 13C NMR, HRMS and X-ray single-crystal diffraction. Some of these compounds （1g, 1h, 1j, 1k） exhibited excellent herbicidal activities against Abutilon theophrasti, Amaranthus retroflexus and Eehinochloa crus-galli at a rate of 375 g AI·ha^-1. Among them, compounds lh and 1j displayed the best post-emergence herbicidal effect against Abutilon theophrasti with ED50 values of 1.8 and 5.3 g AI·ha^-1, respectively, which are superior to that of the commercial acifluorfen （44.3 g AI·ha^-1）. Field trials demonstrated that compound lh exhibited similar herbicidal activity to a high concentration atrazine, and found to be safer for maize than atrazine. The results of this study therefore show that compound lh could potentially be used as a post-emergence herbicide for maize fields.

Synthesis and Herbicidal Activities of Novel Uracil Derivatives Containing Pyrimidinyl Moiety

In order to find novel protoporphyrinogen oxidase inhibitors with high efficacy, broad-spectrum activity, and safety to crops, nine title compounds（4a-4i） were designed and synthesized by introducing pyrimidine moiety into the uracil skeleton with commercially herbicide butafenacil as the lead compound. Their structures were con- firmed by 1H NMR, IR, mass spectroscopy and elemental analysis. The bioassay results indicate that most of com- pounds 4 tested exhibit good to excellent herbicidal activities against B. campestris, A. retroflexus, E. crusgalli and D. sanguinalis in pre-emergence treatment at a dose of 1.5 kg/ha（1 ha=10^4 m^2）, for example, compound 4i showed 100% inhibition against the four plants tested in pre-emergence treatment at a dose of 1.5 kg/ha. So, this type of skeleton can be used as a valuable lead compound for the further development of a pre-emergent herbicide.