Antifungal activity of chalcone derivatives containing 1,2,3,4-tetrahydroquinoline and studies on them as potential SDH inhibitors

Background: A large number of pathogenic fungi have caused serious damage to the global crop yield, and drug resistance is always a topic that cannot be avoided for traditional fungicides. Therefore, finding efficient, green, and low-toxic fungicides is our primary task, which brings opportunities for the development of natural product green pesticides.

Results: Twenty chalcone derivatives containing 1,2,3,4-tetrahydroquinoline were designed and synthesized, and the compounds were tested for their fungicidal effects against eight plant pathogenic fungi in vitro. The results demonstrate that the original splicing did not have fungicidal activity, so a piperazine fragment was introduced; the test results revealed that H1-H10 all had good antifungal activity. Among them, H4 showed the highest inhibitory activity against Phytophthora capsici (Pc) with a median effect concentration (EC₅₀) value of 5.2 μg/mL, which was higher than that of the control drugs Azoxystrobin (EC₅₀ = 80.2 μg/mL) and Fluopyram (EC₅₀ = 146.8 μg/mL). After the study, it was demonstrated that H4 mainly acted on the cell membrane against Phytophthora capsici and inhibited the activity of the marker enzyme of mitochondria (SDH) in the fungus.

Conclusion: H4 has significant resistance to Phytophthora capsici and also plays a significant role in inhibiting SDH activity, providing a new direction for the development of green pesticides. © 2024 Society of Chemical Industry.