LAUSR

BACKGROUND Laccase is a key enzyme in the fungal 1,8-dihydroxynaphthalene(DHN) melanin biosynthesis pathway, which is a potential target for the control of pathogenic fungi. In our previous work, a2 was found with higher inhibition activity against laccase and antifungal activity than laccase inhibitor PMDD-5Y. The introduction of hydrogen-bonded receptors in amino part was found to be beneficial in improving laccase inhibitory activity by target-based-biological rational design. In this work, the hydrogen-bonded receptors morpholine and piperazine were introduced for structure optimization to enhancing biological activity. RESULTS Enzyme activity tests indicated that all target compounds had inhibitory activity against laccase, and some compounds exhibited better activity against laccase than a2, it was further verified the introduction of hydrogen-bonded receptors in the amino portion could enhance the laccase inhibitory activity of target compounds. Most compounds showed excellent antifungal activities in vitro. Compound m14 displayed good activity against Magnaporthe. oryzae both in vitro and in vivo. The SEM analysis showed that the mycelium of M. oryzae treated with m14 were destroyed. Molecular docking revealed the binding mode between laccase and target compounds. CONCLUSION Thirty-eight compounds were synthesized and showed good inhibitory activity against laccase, the introduction of morpholine and piperazine in amino part was beneficial to improve antifungal activity and laccase activity. Further validation of laccase as a potential target for rice blast control, while m14 can be used as a candidate compound for the control of rice blast. This article is protected by copyright. All rights reserved.