antiochratoxigenic activity of antifungal metabolites from Macfadyena cynanchoides

APUD, GISSELLE R.; AREDES FERNANDEZ, P.A.; SAMPIETRO, D.A.

Napa, California

Congreso; 70 th ASEV National Conference; 2019

ASEV

Ochratoxin A (OTA) is a mycotoxin with harmful effects on human and animal health. Aspergillus section Nigri, mainly A. carbonarius and A. niger, are the major species producing OTA in grapes and wine. Special attention is being paid to OTA control in agricultural products because of health risks posed by contaminated food. In recent years, plant extracts and their metabolites have become popular to control mycotoxin-producing fungi. In previous assays, we demonstrated that the dichloromethane extract of Macfadyena cynanchoides stems and their antifungal constituents, identified as 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone (lapachol) and 1-hydroxy-4-methyl anthraquinone, show significant antifungal activity against A. niger and A. carbonarius. The aim of this work was to determine the antiochratoxigenic activity of the dichlorometane extract and their antifungal metabolites, alone and in combination with sodium metabisulfite in different sublethal concentrations. A volume of 4 mL grape juice was supplemented with each antifungal substance and inoculated with 5 × 103 spores/mL of A. carbonarius or A. niger, then incubated for six days at 15°C. At the end of incubation, the amount of OTA produced in the supernatant juice was determined by competitive ELISA using the Ridascreen-Fast ochratoxin A kit. The dichloromethane extract and its antifungal quinones produced a partial inhibition in the OTA production. Sodium metabisulfite induced OTA accumulation at the assayed concentrations. However, the natural antifungals completely suppressed OTA accumulation in mixtures with sodium metabisulfite at all concentrations assayed. We can conclude that the dichloromethane extract of M. cynanchoides and its antifungal molecules have potential use as a complement to sodium metabisulfite against the Aspergillus species responsible for black grape rots and OTA production.