Aflatoxin B1 (AFB1) are mycotoxin secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Consumption of contaminated food with AFB1 endangers life of human being by getting acute aflatoxicosis or chronic aflatoxicosis. The present study aimed to evaluate the in vitro and in vivo antifungal activity of selected medicinal plant extracts and its leaf ashes against Aspergillus flavus and aflatoxin production on maize grains. The A.flavus was isolated from peanuts by blotter method and spore suspension adjusted to1.7x10⁵ spores/ml which were used to inoculate in the maize grains mixed with plant extract of different concentrations. After inoculation, the maize grains were dried and stored in PICS for four weeks then evaluated the effectiveness of plant extracts to inhibit A.flavus by using blotter method. The aflatoxin B1 biosynthesis in the maize grains was extracted by using methanol and water (80:20). Qualitative estimation was done on the TLC plates by visual observation of colour fluorescent spots under UV light (365nm) and was confirmed by comparing obtained R_f value with known standard AFB1 R_f value. T.elegans leaf ash gave the best results, inhibiting A.flavus growth in vitro and in vivo, followed by S.birrea leaf and S.birrea leaf ash whereas other extracts had low inhibition of A.flavus in vitro but no effective inhibition on maize grains. T.elegans leaf ash inhibited also aflatoxin production, almost the same as maize grains stored with Tebuconazole, followed by S.birrea leaf and S.birrea leaf ash which inhibited aflatoxin at 10mg/ml. Other plant extracts were not effective to inhibit aflatoxin production. Therefore, effectiveness of T.elegans leaf ash to inhibit A.flavus growth and aflatoxin production on maize grains could be attributed to the presence of bioactive compounds and alkalinity and hygroscopic character of leaf ash.

Key words: Aspergillus flavus, Aflatoxin, Leaf-ash extract, Inhibition