Abstract:
The antiochratoxigenic (anti-OTA) activity of dichloromethane extract of Macfadyena cynanchoides stems, its antifungal metabolites (lapachol and 1-hydroxy-4-methyl anthraquinone) and sodium metabisulfite was evaluated alone and in combination with this commercial preservative 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 in the sub-lethal concentrations after incubating in the dark for 6 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 30-60% respect to control at extract concentrations of 625-1250 µg/mL. Both lapachol and 1H4MA tested at 625 µg/mL exerted a similar anti-OTA effect with an average inhibition of 30%. In the case of sodium metabisulfite, it increased OTA production between 60 to 100% at all the sub-lethal concentrations. Binary mixtures of extract or lapachol or 1H4MA + sodium metabisulfite tested 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 a little the time required for completion of the alcoholic fermentation, but did not reduce the Saccharomyces cerevisiae viability or modify physico-chemical parameters measured at the end of the process. Our results show that the mixture sodium metabisulfite + lapachol has potential as an antifungal and anti-OTA agent useful to reduce the doses of sulfites in the control of Aspergillus on post-harvested grapes.
- Received March 2021.
- Revision received August 2021.
- Revision received September 2021.
- Accepted October 2021.
- Published online November 2021
- Copyright © 2021 by the American Society for Enology and Viticulture. All rights reserved.
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