Search for novel antifungals from 49 indigenous medicinal plants: Foeniculum vulgare and Platycladus orientalis as strong inhibitors of aflatoxin production by Aspergillus parasiticus

In a search for novel antifungals from natural sources, essential oils (EOs) and extracts of 49 medicinal plants were studied against an aflatoxin (AF)-producing Aspergillus parasiticus using a microbioassay technique. AF levels were measured in culture broth by high performance liquid chromatography. The EOs were analyzed by gas chromatography/mass spectrometry (GC/MS). Based on the results obtained, Achillea millefolium subsp. elborsensis, Ferula gummosa, Mentha spicata, Heracleum pubescens and Thymus fedtschenkoi markedly inhibited A. parasiticus growth by IC50 values of 35 to 1,815 mu g/ml without affecting AF production by the fungus. The EOs of flowers and roots of Foeniculum vulgare significantly inhibited both fungal growth (similar to 70.0%) and production of AFs B-1 and G(1) (similar to 99.0%). The ethyl acetate extract of Platycladus orientalis leaves suppressed AFB(1) (similar to 90.0%) but not fungal growth and AFG(1) production. This work provides evidence for the first time that F. vulgare and P. orientalis are strong inhibitors of aflatoxin biosynthesis in A. parasiticus. The antifungal activities of the bioactive plants introduced in the present study could make an important contribution to explaining the use of these plants as effective antimicrobial candidates to protect foods and feeds from toxigenic fungus growth and subsequent AF contamination.