Viscosimetric study and synergistic antifungal activity of oils extract from three Algerian medicinal plants against toxigenic Aspergillus

Oils extracted from seeds of three medicinal plants used in Algerian folk medicine (Citrullus colocynthis, Nigella sativa and Linum usitassimum), were tested for their antifungal synergyagainst one strain of Aspergillus flavus toxin (A. flavus MTTC 2799) by the method of radial growth on solid medium Potateos Dextrose Agar (PDA). Antifungal results revealed that all oils tested at the concentration 1/5000 inhibited the growth of the studied fungus, where the best antifungal potency was observed for the L. usitassimum seed oil. The values ofantifungal indices (55.65, 48.65, 40.54) were recorded, respectively for L. usitassimum oil,C. colocynthis oil and N. sativa oil at concentrations of (1/5000, 1/500 and 1/2000). The results of the synergistic antifungal activity obtained by oils combination revealed that L.oil/C. oil showed the best antifungal effect (54.19%) before the L. oil/C.oil/N. oil system with 48.76% of inhibition. In order to explain the synergistic effect and the best behavior of oils, especially determination of optimal concentrations C* (C star) needed for antifungal synergistic activity, viscosimetric investigation was carried out at room temperature and at several concentrations.   Key words: Viscosity, oil carbon chain, synergistic antifungal activity, oils, Aspergillus flavus.