Pdf download Anti-fungal activity of five studied plant extracts compared with propolis and their effect on aflatoxigenic production and expression of aflatoxin biosynthesis genes of studied Aspergillus flavus isolates

Abstract

This study was designed to evaluate fungal activity of five plant extracts namely; Ammi majus, Camellia sinensis, Trifolium alexandrinum, Humulus lupulus, and Linum usitatissimum (seeds), and propolis against an aflatoxin-producing Aspergillis flavus isolate. Their ability to inhibit production of four aflatoxins (B₁, B₂, G₁ and G₂) was studied, too. Four isolates of Aspergillus flavus were isolated from infected wheat grain collected from local markets at Alexandria governorate, Egypt. Fungal isolates were molecularly identified as; A. flavus 1 (acc#: OR477304), A. flavus 2 (acc#: OR478624), A. flavus 3 (acc#: OR478625) and A. flavus 4 (acc#: OR477305). Six concentrations of the five plant extracts and propolis were used (0.0, 0.01, 0.05, 0.1, 0.5 and 1 g/50 ml) to study their anti-fungal activity against A. flavus 3 (OR478625). All treatments produced significant reduction in the percentage of fungal biomass’s growth when compared to control. The highest reduction in fungal biomass by A. majus (50.8%) and T. alexandrinum (54.6%) appear at 0.01 and 0.5 g/50ml. For C. sinensis the highest reduction in growth biomass (60.6%) appear at 0.01 g/50ml. In contrast to H. lupulus and L. usitatissimum, the highest reduction in growth biomass appears at 1 g/50ml are 38.4% and 61.6% respectively. Propolis exhibited the highest reduction in fungal biomass (48.2%) at 0.5 g/50 ml. Production of AFs by A. flavus OR478625 in broth medium were significantly affected by plant extracts, in contrast to propolis. The plant extract of A. majus cause complete inhibition of the four types of AFs production (B₁, B₂, G₁ and G₂) at all studied concentrations. As for C. sinensis extract complete inhibition appeared for only three types of AFs (B₂, G₁ and G₂) under all concentrations. In addition, H. lupulus extract caused complete inhibition for the four AFs at 0.5 and 1% concentrations. As for T. alexandrinum extract complete inhibition of the four AFs was achieved at 0.01 and 1%. Regarding L. usitatissimum extract AFG₁ was inhibited at all concentrations. Propolis completely inhibited the four studied aflatoxins at 0.5 and 1 %. Quantity of studied secondary metabolites varies from one extract to others. Phenolics ranged from 121 to 322 mg/g, flavonoids from 50 to 85 mg/g, ascorbic acid from 10 to 36 mg/g, saponins from 17 to 36 mg/g and tannins from 11 to 35 mg/g, for studied plant extracts. Three methods were used for studding antioxidant activity. For FRP and DPPH methods the highest antioxidant activity appeared with A. majus (35.8±3 mg/g and 81±3%) respectively, but for PMA methods the highest antioxidant activity appeared with H. lupulus (30±2 mg/g). Meanwhile, propolis exhibited 30.8, 76.4 and 11.5 antioxidant capacity using FRP, DPPH and PMA methods, respectively. Additionally, treatment of A. flavus 3 with A. majus, showed remarkable variations in genes expression when compared to control. This study presented the antioxidant properties, antifungal capacity and inhibitory effect on aflatoxin production of the studied plant extracts and propolis, as well.