Synthesis and bioactivities of amino acid ester conjugates of phenazine-1-carboxylic acid.

Phenazine-1-carboxylic acid (PCA) is a natural product that has been characterized by special chemical structures, interesting bioactivities and has been registered for fungicide against rice sheath blight in China. Phloem mobility is of great significance to long-distance transport of systemic pesticides in plants. In order to improve the phloem mobility and bioactivities of PCA, seventeen PCA-amino acid ester conjugates were designed and synthesized by conjugating PCA with different amino-acid esters. The conjugates were evaluated for their fungicidal activities against Rhizoctonia solani Kuhn and their phloem mobility was determined by HPLC. Results showed that conjugates a, b, c, d, e, l, m and p (EC50 values between 5.35 and 18.85μg/mL) were more active than PCA (25.66μg/mL). In particular, conjugates l and m exhibited the best fungicidal activities against Rhizoctonia solani Kuhn (EC50 values of them were 6.47μg/mL and 5.35μg/mL respectively). All these conjugates didn't have phloem mobility.