Virtual screening for the discovery of lawsone derivatives as PS Ⅱ inhibitors

Photosynthesis system Ⅱ (PS Ⅱ) inhibitors can block electron transport and disrupt plant photosynthesis and are used as herbicides. In order to develop new and effective PS II inhibitors, the lead structure lawsone was first found with remarkable herbicidal activity based on a virtual screening strategy, and its derivatives were designed and synthesized. The results of herbicidal activity evaluation showed that most of the compounds could achieve more than 80 % inhibitory effect on roots and stems of Portulaca oleracea at a dose of 100 μg/mL. Meanwhile, compound 4d showed more than 90 % inhibition on the stem of P. oleracea and on the root of Echinochloa crusgalli, which were superior to lawsone (64.9 and 67.6 %) and atrazine (63.6 and 65.9 %), respectively. Interestingly, 4d exhibited 100 % post-emergence herbicidal activity to Amaranthus retroflexus and Abutilon theophrasti at a dosage of 300 g a.i./ha, which was similar to atrazine but superior to lawsone. In addition, compound 4d can affect the efficiency of the photochemical process and strong bind PS II D1 protein. It revealed that compound 4d can be used as a promising PS II D1 inhibitor. This study provides a promising lead compound for developing new PS II inhibitors.