Synthesis and bioactivities of phenazine-1-carboxylate derivatives containing acetophenone structural fragments

To improve the bioactivities of phenazine-1-carboxylic acid (shenqinmycin), 22 phenazine-1-carboxylate derivatives containing acetophenone structural fragments 3a - 3c and 6a - 6s , which have not been reported in literatures were synthesized by bromination reaction and nucleophilic substitution using phenazine-1-carboxylic acid and different substituted acetophenone as raw materials. And their structures were confirmed by ¹H NMR, ¹³C NMR and high resolution mass spectrometry. The fungicidal activities of the target compounds against 6 plant pathogens and the acaricidal activities of adult mite of Tetranychus cinnatarinus were determined by mycelial growth rate method and agar moisturizing leaf soaking method, respectively. The results of fungicidal activity assay showed that most of the target compounds had certain inhibitory activities against Rhizoctonia solani. At the concentration of 0.2 mmol/L, the inhibition rates of compounds 6b and 6e against R. solani were 56.05% and 65.37%, respectively, which were lower than that of the control compound phenazine-1-carboxylic acid (86.83%). The results of acaricidal activity determination showed that: at 1 mmol/L, the corrected mortality rates of compounds 6k and 6m were 87.88% and 90.82%, respectively, and the LC₅₀ values of compounds 6k and 6m against adult mite of T. cinnatarinus were 0.25 mmol/L and 0.19 mmol/L, respectively. The new compounds synthesized in this work not only had certain fungicidal activities, but also had better acaricidal activities. It provided a new idea for the further structural modification of phenazine-1-carboxylic acid.