trans-Cinnamic and Chlorogenic Acids Affect the Secondary Metabolic Profiles and Ergosterol Biosynthesis by Fusarium culmorum and F. graminearum Sensu Stricto

Abstract

Plant-derived compounds limiting mycotoxin contamination are currently of major interest in food and feed production. However, their potential application requires an evaluation of their effects on fungal secondary metabolism and membrane effects. In this study, different strains of Fusarium culmorum and F. graminearum sensu stricto were exposed to trans-cinnamic and chlorogenic acids on solid YES media. Fusaria produced phenolic acids, whose accumulation was lowered by exogenous phenolic compounds. In addition, fungi reduced exogenous phenolic acids, leading either to their conversion or degradation. trans-Cinnamic acid was converted to caffeic and ferulic acids, while chlorogenic acid was degraded to caffeic acid. The latter underwent further degradation to protocatechuic acid. Fungal-derived trans-cinnamic acid, as the first intermediate of the shikimate pathway, increased after chlorogenic acid treatment, presumably due to the further inhibition of the conversion of trans-cinnamic acid. Exogenous trans-cinnamic and chlorogenic acid displayed the inhibition of mycotoxin production by Fusaria, which appeared to be largely dependent on the phenolic compound and its concentration and the assayed strain. Exogenous phenolic acids showed different effects on ergosterol biosynthesis by fungi. It was found that the production of this membrane sterol was stimulated by trans-cinnamic acid, while chlorogenic acid negatively impacted ergosterol biosynthesis, suggesting that phenolic acids with stronger antifungal activities may upregulate ergosterol biosynthesis by Fusaria. This paper reports on the production of phenolic acids by Fusaria for the first time.

Sinapic Acid Affects Phenolic and Trichothecene Profiles of F. culmorum and F. graminearum Sensu Stricto

“…The need for the discovery and development of novel disease management strategies to control Fusaria is nowadays of great importance due to the loss of existing products through the development of fungicide resistance and the desire for products with more favorable environmental impact [ 10 , 31 ]. The recent evidence from in vitro studies on the effect of phenolic acids on Fusaria provides the scientific framework for developing and adapting strategies incorporating the application of these compounds to reduce mycotoxin load in plant-derived foods [ 9 , 10 , 20 ].…”

“…One proposed hypothesis is that phenolic acids affect trichothecene biosynthesis at a transcriptional level [ 32 ]. Inhibition of the expression of Tri genes has been recently confirmed by trans -cinnamic acid, the precursor of the other phenylpropanoids [ 20 ]. Other studies have provided corresponding evidence on the mechanism of action of ferulic acid [ 9 ], exhibiting antioxidant and antiradical properties similar to sinapic acid ( Table 2 ).…”

“…Recent in vitro studies demonstrated the inhibitory activities of cinnamic-derived phenolic acids (ferulic, chlorogenic and trans -cinnamic acid) against trichothecene production by F. culmorum and F. graminearum s.s. [ 9 , 10 , 19 , 20 ]. However, no data is available regarding the response of fungi to sinapic acid, which is among the most common hydroxycinnamic acids widespread in the plant kingdom.…”

“…Other limited studies showed that the ascomycete fungi can transform exogenous sinapic acid to syringic acid via propenoic chain cleavage, which appears to be common in filamentous fungi [ 25 , 26 ]. A recent study showed that Fusaria can produce sinapic acid in vitro, comprising around 15% of the sum fungal-derived phenolic acids [ 20 ]. Production of phenolic acids appears to be common in fungi (including the genus Fusarium ), which suggests that the ability to synthesize these secondary metabolites is important in the life cycle of fungi [ 20 ].…”

“…A recent study showed that Fusaria can produce sinapic acid in vitro, comprising around 15% of the sum fungal-derived phenolic acids [ 20 ]. Production of phenolic acids appears to be common in fungi (including the genus Fusarium ), which suggests that the ability to synthesize these secondary metabolites is important in the life cycle of fungi [ 20 ].…”