Objetives: To study the effects of: a) the Origanum vulgare essential oil (OEO), b) the OEO main components thymol and terpineole (individually), and c) a mixture of thymol and terpineole; on the fumonisin B1 (FB1) production by F. verticillioides MRC 826 in corn grain.

Methods: Autoclaved maize was inoculated with 200 uL of a conidia suspension prepared as described previously (1). Incubation lasted 28 days in the dark at 27ºC. At the 17^th, 20^th y 23^th days post inoculation; the OEO, thymol and terpineole were applied on a paper disk and then placed in the center of Petri dishes containing the corn grain inoculated with the fungus. The OEO was added in final proportions of 20 and 30 ppm. Thymol, as well as terpineol, was incorporated to the maize at 4 and 6 ppm, representing the levels found for these compounds in the concentrations of OEO studied, respectively. Separation and quantification of FB1 were done as described Voss et al. and Shephard et al., respectively (2, 3).

Results: While the addition of 20 ppm of OEO induced the FB1 production; this parameter was not affected after the OEO main components, thymol and terpineole, were incorporated to maize in the lowest concentrations studied. When the OEO, thymol and terpineole were incorporated at the highest levels evaluated, inhibitory activities on the biosynthesis of FB1 were registered, in the following order: thymol>OEO>terpineole. This tendency was observed for the three insertion days studied.

Conclusions: This study suggests that thymol and OEO could be effective on corn grain, to decrease the FB1 production with F. verticillioides.

References:

1. Torres A. M., et al. 2003. International Journal of Food Microbiology 83: 319-324.

2. Voss, K, A., et al. 1990. Mycopathologia 112:81-92.

3. Shephard, G. S., et al. 1990. Journal of Liquid Chromatography 13:2077-2087.