Design, Synthesis and in Vitro Antifungal Mechanism of Novel Phenylalanine Derivatives

To explore novel molecules with unique mechanisms against plant pathogenic fungi, a series of phenylalanine derivatives containing a 1,3,4-oxadiazothioether moiety were designed and synthesized. Bioassays revealed that some target compounds at 100 mu g/mL exhibited excellent antifungal activities against Thanatephorus cucumeris, such as G(6) (92.1 %), G(10) (94.3 %), G(18) (99.1 %), and G(19) (98.7 %), better than that of the commercial fungicide azoxystrobin (90.6 %), and the EC50 value of G(10) against T. cucumeris was 31.9 mu g/mL. Further mechanism studies of T. cucumeris treated with G(10) demonstrated that this compound can affect the growth of mycelia by disrupting the integrity of the membrane, and the higher the concentration of the compound is, the greater the degree of membrane integrity damage, similar to the commercial fungicide azoxystrobin. These conclusions provide important information for further mechanism studies of this series of phenylalanine derivatives.