In Vitro Antifungal Activity of Composites of AgNPs and Polyphenol Inclusion Compounds against Fusarium culmorum in Different Dispersion Media

Petruta Matei,Petruta Matei,Beatrice Iacomi,Eduardo Pérez-Lebeña,Jesús Martín-Gil,M Barrio-Arredondo,Pablo Martín-Ramos,M Ramos-Sánchez

doi:10.3390/agronomy8110239

Abstract

Fusarium culmorum is a soil-borne fungus able to cause Fusarium head blight, one of the most important cereal diseases worldwide, which can result in significant yield losses of up to 50% and which jeopardizes food and feed safety due to the mycotoxins produced. In the study presented herein, the enhancement of the antifungal activity against this pathogen, resulting from the addition of silver nanoparticles (AgNPs) to different polyphenol-stevioside inclusion compounds, dispersed either in a chitosan oligomers hydroalcoholic solution or in a choline chloride:urea:glycerol deep eutectic solvent, was investigated in vitro. The polyphenols assayed were curcumin, ferulic acid, gallic acid and silymarin. Four composite concentrations (62.5, 125, 250 and 500 µg·mL−1), with and without AgNPs, were assessed, finding noticeable differences in mycelial growth inhibition, with EC50 and EC90 values ranging from 118 to 579 µg·mL−1 and from 333 to 2604 µg·mL−1, respectively. The obtained results evidenced the improved efficacy of the composites with AgNPs, a superior performance of the composites based on curcumin and ferulic acid, and the advantages of the deep eutectic solvent-based dispersion medium over the chitosan oligomers-based one. The reported composites hold promise for crop protection applications.

Highlights

IntroductionFusarium head blight (FHB) remains one of the most important diseases worldwide and continues to pose a major challenge in cereal production leading to severe yield reductions
Chitosan oligomers were prepared from medium molecular weight chitosan
It should be stressed that Fusarium species do not have a normal minimum inhibitory concentration (MIC) and minimum effective concentration (MEC) distribution and prediction of antifungal susceptibility of a single strain is difficult ([34] and references therein)

Summary

Introduction

FHB remains one of the most important diseases worldwide and continues to pose a major challenge in cereal production leading to severe yield reductions. This fungus is reported as a post-harvest pathogen, especially on freshly harvested grain that has not been properly dried or stored [1]. It produces type B trichothecenes (4-deoxynivalenol, 3-acetyl-4-deoxynivalenol, 15-acetyl-4-deoxynivalenol, nivalenol and 4-acetylnivalenol or fusarenone X), which may contaminate food and feed at high concentrations and cause serious poisoning in humans and animals [3]. Trichothecenes play an important role as virulence factors by inhibiting defense mechanisms activated by the plant [1]

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Discussion

Conclusion