Antifungal activity of eucalyptus microtheca leaves extract against aflatoxigenic fungi

Abstract

Eucalyptus trees are evergreen, fast-growing, and widely cultivated in Iraq. Its leaves, buds, capsules, and even seeds contain several compounds that have antimicrobial activity. Fresh leaves were collected and let dry in the shade at room temperature, then alcoholic, and aqueous stock solution (200mg/ ml) of leaves extract was prepared in 10% DMSO from which different concentrations were done. Antibiotic susceptibility test was performed by the disk diffusion method using FLU, KCA, MCL, ECN, and ITC antibiotics. Leaves extracts were also examined for its antifungal activity then the MIC and MFC were determined using the microdilution method. KCA, ECN, and MCL were the most effective antifungal drugs on most isolates. Only two isolates were resistant to all antibiotics, and one isolate showed sensitivity to all antibiotics under study. The methanolic and ethanolic extract of Eucalyptus leaves extract showed the highest inhibitory influence on fungal growth in comparison with the aqueous extract. Furthermore, Alcoholic extracts showed MIC at 50mg/mL and MFC at 100mg/ml. The aqueous extract of Eucalyptus had no inhibitory effect on the growth of all Aspergillus isolates. The results of the present research showed the potential antifungal activity of the Eucalyptus microtheca leaves extract against the aflatoxigenic A. niger and A. flavus, which is an indication of the fungicidal value of the plant extract. This research suggests that the plant extract may possess some compounds with antifungal properties against fungi, and it can be used as a safe and economical alternative against aflatoxigenic fungal food and feed contamination.