Antifungal Activity of Sesamol on Pestalotiopsis neglecta: Interfering with Cell Membrane and Energy Metabolism

Abstract

This paper investigated the inhibitory effect of Sesamol (Ses) on Pestalotiopsis neglecta. The potential inhibitory mechanisms were explored by observing changes in cell morphology, measuring alterations in cell membrane-related indices, as well as energy metabolism-related indices and changes in enzyme activities related to virulence. The results show that Ses completely inhibited the growth of P. neglecta at 600 μg/mL (minimum inhibitory concentration and minimum fungicidal concentration), with an EC50 of 142 ± 13.22 μg/mL. As observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Ses treatment resulted in the breakage and crumpling of P. neglecta cell membrane and organelle lysis. Ergosterol content and the total lipid in P. neglecta treated with 300 μg/mL Ses was 91.52% and 54% of that in the control groups, respectively. In addition, spores were stained, increased leakage of intracellular constituents at 260 nm, and decreased extracellular pH. This suggests damage to the cell membrane integrity and permeability. Furthermore, Ses decreased the ATP levels and key enzymes in the tricarboxylic acid (TCA) cycle, indicating interference with the fungal energy metabolism. Moreover, the activities of polygalacturonase (PG) and endoglucanase (EG) of P. neglecta treated with 300 μg/mL of Ses were only 28.20% and 29.13% of that in the control groups, respectively, indicating that Ses can reduce the virulence of P. neglecta. In conclusion, our results show that Ses should be considered as a potential plant-derived fungicide due to its ability to disrupt the morphology of P. neglecta, damage cell membrane integrity and permeability in P. neglecta, interfere with energy metabolism, and reduce its virulence, ultimately affecting the fungal growth.