Design, synthesis, and antifungal activity of 14-aryloxy/amide substituted andrographolide derivatives

In order to find more compounds with antifungal activities, a series of new compounds were designed and synthesized using the natural product of diterpenoid lactones, andrographolide, as the parent nucleus. Target compounds were identified by ¹H NMR, ¹³C NMR and/or HR-MS. The bioassay results demonstrated that compound 4d exhibited inhibition rates of over 60% against six fungal strains at 100 µg/mL, and the EC₅₀ value of 4d against P. piricola was only 9.09 µg/mL. SEM test showed that 4d could damage the mycelia of P. piricola. obviously. Moreover, 4d had no effect on cowpea seed germination, showing high safety.