Design and synthesis of novel cinnamamide derivatives-based lansiumamide B as potent fungicidal candidates

BACKGROUND Natural products have been and continue to be a significant resource for developing environmentally friendly pesticides with distinctive structures and mechanisms. Lansiumamide B (LB), a cinnamamide compound extracted from Clausena lansium seeds, has served as the lead compound for the design and synthesis of a series of cinnamamide derivatives. The fungicidal activity of these derivatives has been evaluated. RESULTS The majority of the proposed compounds displayed moderate to considerable antifungal efficacy against the tested pathogenic fungi and oomycetes, with some exhibiting broad-spectrum fungicidal activities. Compound B 26 showed excellent activity against Colletotrichum orbiculare in vitro , with a median effective concentration (EC 50 ) value of 0.36 μg/mL, better than positive control boscalid (0.95 μg/mL) and the lead compound LB (60.18 μg/mL). In vivo , B 26 also exhibited greater fungicidal activity against C. orbiculare than boscalid and LB. Furthermore, the study found that the mycelium cell wall was damaged after treatment with compound B 26 through observation of the mycelial morphology and ultrastructure of C. orbiculare . Consequently, mycelial growth was inhibited. CONCLUSION The results indicated that cinnamamide compounds containing a 1,2,3,4-tetrahydroisoquinoline moiety represent a novel class of antifungal active scaffold, and compound B 26 has the potential to be developed into a new type of fungicide. © 2025 Society of Chemical Industry.