Quinones of Macfadyena cynanchoides for Control of Aspergillus carbonarius and Aspergillus niger in Wine

Abstract

Antiochratoxigenic activity (anti-OTA) of dichloromethane extract of Macfadyena cynanchoides stems, its antifungal metabolites (lapachol and 1-hydroxy-4-methyl anthraquinone), and sodium metabisulfite were evaluated alone and in combination for their effect on Aspergillus species at sub-lethal concentrations. Grape juice inoculated with 5 × 10³ spores/mL of A. carbonarius or A. niger was supplemented with the extract (2500 to 156.3 µg/mL), the quinones (1250 to 78.1 µg/mL), or sodium metabisulfite (2500 to 156.3 µg/mL). OTA accumulation was measured for the sub-lethal concentrations after incubating in the dark for six days at 15°C. The extract and sodium metabisulfite completely inhibited growth of both fungi at 2500 µg/mL, while lapachol and 1H4MA required 1250 µg/mL. Average OTA biosynthesis declined to 30 to 60% less than the control at extract concentrations of 625 to 1250 μg/mL. Both lapachol and 1H4MA at 625 μg/mL exerted a similar anti-OTA effect, with an average inhibition of 30%. Sodium metabisulfite increased OTA production 60 to 100% at all sub-lethal concentrations. Binary mixtures of extract or lapachol or 1H4MA + sodium metabisulfite, at concentrations of 9.8 + 156.3 µg/mL, 19.5 + 312.5 µg/mL, and 39.1 + 625 µg/mL, completely inhibited OTA production. In addition, the mixture lapachol + sodium metabisulfite (9.8 + 156.3 µg/mL) delayed the time required to complete alcoholic fermentation, but did not reduce Saccharomyces cerevisiae viability or modify physicochemical parameters at the end of fermentation. The mixture sodium metabisulfite + lapachol has potential as an antifungal and anti-OTA agent to reduce the dose of sulfites to control Aspergillus on grapes postharvest.