Resveratrol, Lentinula edodes and BHA: novel opportunities in the prevention of fungal growth and mycotoxin production in foodstuffs.

The deterioration of foodstuffs by fungi is a widespread problem with serious implications for human and animal health and for economic aspects. Fungal contamination not only gives rise to off flavours and other degradation phenomena, but can also lead to the production of mycotoxins. These are well known products of secondary metabolism in different species of fungi and have genotoxic, teratogenic, and immunotoxic effects. Different strategies are used for the control of mycotoxins both in the field and during storage: physical, chemical, biological or genetic. Among these we have focused on the prevention of fungal growth and mycotoxins production during storage by a chemical food grade treatment. Wheat and maize seeds were used, unsterilized or sterilized by γ rays and Aspergillus ochraceus or Fusarium graminearum [Gibberella zeae]; ochratoxin A and zearalenone producers, respectively. Seed samples have been treated with butylated hydroxyanisole (BHA), resveratrol (resv) or Lentinula edodes (L.f.) cultural filtrates. These compounds have been selected because of their antioxidant or antimicrobial activities, since mycotoxins are secondary metabolites and so their production is somehow linked to an increase of oxidative metabolism. The samples treated with BHA, resv or L.f. were incubated under different environmental conditions (aw = 0.85 or 0.95; temperature = 25 or 28°C). The assayed treatments showed different inhibition rates of fungal growth or toxin production also depending on the environmental conditions considered. Moreover, a high homology (91% similarity and 86% identities) was verified between the main fragment originated at 0.5 Kb after a PCR amplification of A. ochraceus DNA and atrB of Aspergillus nidulans. This is an ATP binding cassette transporter involved with fungal resistance to plant defence toxins. This finding could mean that A. ochraceus could use this transporter to discard out of the cell different toxic molecules. The results obtained illustrate the promising effect of the compounds tested on the control of fungal growth and toxin production