Abstract

The efficiency of five methanolic plant extracts obtained from Euclayptus globolus, Olea europaea, Salvadora persica, Thymus vulgaris and Ziziphus spina-christi were investigated for their inhibitory effect on the growth and aflatoxin B₁ production of the toxigenic Aspergillus flavus strain isolated from wheat seeds. Extract of T. vulgarisshowed the highest antifungal and antiaflatoxigenic activities as aflatoxin B₁ production was absolutely arrested at 5 mg/ml, while the mycelial growth of A. flavus was completely inhibited at 15 mg/ml. E. globolus and O. europaea extracts showed a moderate antifungal activities and exhibited a significant antiaflatoxigenic efficiency as they inhibited aflatoxin B₁production at 15 mg/ml. On the other hand, S. persica showed weak antifungal activities while no effect was detected with Z. spina-christi extract. The analysis of plant extracts by GC/MS revealed that T. vulgaris extract was mainly composed by thymol (38.73%), carvacrol (19.31%) and ρ-cimene (10.13%), O. europaea extract was composed by anthracenedione (20.63%), terbutaline (13.96%) and propiolic acid (12.02%) while eucalyptol (30.62%), globulol (18.94%) and silane (9.13%) were the principal components of E. globolus extract. These extracts of T. vulgaris, E. globolus and O. europaea which are effective and environmentally safe are promising for protecting wheat seeds against aflatoxigenic strain of A. flavus.

Key words: Aflatoxins, wheat, antiaflatoxigenic, methanolic extracts, Euclayptus globolus, Olea europaea, Salvadora persica, Thymus vulgaris.