Natural Product Research · 2019 · 21 citations · 9 references
Phenazine-1-carboxylic acid (PCA) as a natural product which has significant inhibition effects against many soil-borne fungal phytopathogens in agricultural application and has been registered in China as the fungicide against rice sheath blight. In order to find new higher fungicidal activities lead compounds and develop new eco-friendly agrochemicals, we introduced substructure piperazines which also have high biological activity into PCA, designed and synthesized a series of phenazine-1-carboxylic piperazine derivatives, and their structures were confirmed by <sup>1</sup>H NMR and HRMS. Most compounds exhibited certain <i>in vitro</i> fungicidal activities. In particular, Compounds <b>5r</b> exhibited the activity against all the tested pathogenic fungi, such as <i>Rhizoctonia solani</i>, <i>Alternaria solani</i>, <i>Fusarium oxysporum</i>, <i>Fusarium graminearum</i>, <i>Pyricularia</i> oryzac Cavgra, with the EC<sub>50</sub> value of 24.6μM, 42.9μM, 73.7μM, 73.8μM, 34.2μM, respectively, more potent activities than PCA (33.2μM, 81.5μM, 186.5μM, 176.4μM, 37.3μM). This result provided a highly active lead compound for the further structure optimization design.
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