Antifungal Activity of a New Phenolic Compound from Capitulum of a Head Rot-resistant Sunflower Genotype

Abstract

In a previous study, we observed that bract and corolla extracts from a Sclerotinia sclerotiorum-resistant sunflower contained high amounts of the known coumarins scopoletin, scopolin, and ayapin. There was a correlation between coumarin concentration and disease resistance. Thin layer chromatography showed higher concentrations of three other compounds in the resistant genotype when compared to the susceptible. A bioassay-directed purification that used column chromatography and HPLC allowed the isolation of a new compound, 3-acetyl-4-acetoxyacetophenone, and known compounds, demethoxyencecalin and 3-acetyl-4-hydroxyacetophenone. Structures were assigned from spectral data, and bioactivities were characterized by in vitro bioassays against S. sclerotiorum. The new compound, 3-acetyl-4-acetoxyacetophenone, had an antifungal activity similar to the coumarin ayapin, previously described as a potent Sclerotinia inhibitor. The speed and simplicity by which these compounds can be detected make them suitable for use in screening procedures that may identify genotypes with valuable levels of resistance. A screening of seven sunflower genotypes in a field experiment showed a correlation between these compounds and resistance to Sclerotinia.

Phenolics and antifungal activities analysis in industrial crop Jerusalem artichoke (Helianthus tuberosus L.) leaves

“…The spore suspension was adjusted with sterile saline solution to a concentration of approximately 1.0 × 10 5 in a final volume of 100 L per well. Microdilution tests (Hänel and Raether, 1988;Daouk et al, 1995;Wanger et al, 1995;Espinel-Ingroff et al, 2002;Favre et al, 2003;Prats et al, 2007) were performed in 96-well plates in order to determine the antifungal activity of the samples against phytopathogenic fungi E. turcicum and G. zeae. The samples were diluted in distilled water to give serial twofold dilutions that were added to each medium, resulting in concentrations ranging from 0.49 to 1000 g mL −1 .…”

“…chlorogenic acid; Sinden et al, 1988;Friedman, 1997;Percival et al, 1999). Twelve phenolic compounds (including chlorogenic acid) were effective in inhibiting Xylella fastidiosa growth (Maddox et al, 2010), whereas a new phenolic compound had antifungal activity against Sclerotinia sclerotiorum (Prats et al, 2007).…”

An Introductory Chapter: Secondary Metabolites

“…Phenolic compounds act as antioxidants protecting cells from oxidative stress scavenging of free radicals by hydrogen atom donation. The action of phenolic as neuroprotective [18], fungicidal [19], bactericidal [20] compounds and their anti-atherosclerosis [21] effects, and anticancer [22] activity is well documented.…”

1-(5-Acetyl-2-hydroxyphenyl)ethanone

“…The title compound is known for its high antifungal activity (Prats et al, 2007). In the molecule, the hydroxy-group is disordered over two positions [O1-H10 and O1A-H10A with occupancies of 0.769 (3) and 0.231 (3), respectively] related to each other via 180° rotation about the C3-C6 molecule axis.…”