Unraveling the polypharmacology of a natural antifungal product, eugenol, against Rhizoctonia solani

Abstract

BACKGROUND: Rice sheath blight caused by Rhizoctonia solani is a devastating disease of rice in China. However, indiscriminate use of chemical fungicides applied to control the disease raise major environmental and food safety issues. Ecofriendly biocontrol alternatives are urgently needed. Eugenol, one of the main ingredients in Syzygium aromaticum, has attracted much attention owing to its antifungal properties. However, its mode of action is still not clear. Herein, the antifungal activity and mode of action of eugenol against R. solani were investigated.RESULTS: Results confirmed that the mycelia of R. solani treated with eugenol shrank and became dehydrated, the cytoplasmic wall separated, and the vacuoles and mitochondria decreased or dissolved. Moreover, we found that eugenol downregulated expression of C-4 methyl sterol oxidase, inhibited synthesis of ergosterol, increased membrane permeability and impaired the transportation of amino acids and glucose across the cell membrane. In addition, eugenol decreased the mitochondrial membrane potential and initiated an oxidative stress reaction by increasing reactive oxygen species and malondialdehyde, which together with membrane damage contribute to the antifungal activity of eugenol. Meanwhile, eugenol might inhibit R. solani by affecting oxidative phosphorylation and the tricarboxylic acid cycle (TCA cycle). CONCLUSION: In view of its multitarget properties against R. solani, eugenol provides an alternative approach to chemical control strategies against rice sheath blight.

Novel Pyrazole Carboxamide Containing a Diarylamine Scaffold Potentially Targeting Fungal Succinate Dehydrogenase: Antifungal Activity and Mechanism of Action

“…To further investigate the antifungal activities of novel pyrazole carboxamide against R. solani, their in vivo antifungal activities were evaluated by pot tests. − Compound SCU3038 (EC 50 = 0.95 mg/L) exhibited higher antifungal activity against R. solani than fluxapyroxad (EC 50 = 2.29 mg/L) and thifluzamide (EC 50 = 1.88 mg/L) in Table , and this was consistent with previously reported antifungal activity in vitro .…”

Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release

“…While bare MSN, pure eugenol, eugenol encapsulated in non-gated MSN, and eugenol encapsulated in MSN gated with glucose or starch did not prevent A. niger growth, particles consisting of eugenol encapsulated in MSN gated with maltose and maltodextrin did. The antimicrobial activities of eugenol are widely accepted [ 43 ] and its antifungal mechanism of action was recently proposed [ 44 ]. Additionally, experiments with its encapsulation and/or nanoparticles preparation are reported [ 45 , 46 , 47 ], mainly against food-borne or human pathogens, showing its wide antimicrobial potential.…”

Rhizoctonia solani Kühn Pathophysiology: Status and Prospects of Sheath Blight Disease Management in Rice

“…Eugenol from clove ( Syzygium aromaticum L .) has been found to control this pathogen by dehydrating the cell and increasing the cell membrane permeability ( Zhao et al, 2021 ).…”