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AN AGRICULTURAL soil was used to isolate Alternaria alternata. It was molecularly identified and was given an accession number MN645469 at the National Center for Biotechnology Information (NCBI) and a strain identifier to be Alternaria alternata strain NMK1. Four fractions were collected from the acetic acid extract of its filtrate. Fraction no. 2 showed highest antioxidant activity (71 and 64%, at 200 and 150μg/mL) followed by the crude extract (60 % at 200μg/mL). Safety of using the extracted fractions was tested against the normal human amnion (WISH) cell line. Lowest cytotoxicity values were recorded for fraction no. 2 (19%) followed by the crude extract (28%) at 50μg/mL. Aspergillus flavus, Aspergillus niger and Penicillium griseofulvum exhibited highest relative density percentages (28.4, 30.8 and 24.3%) on their respective isolation seeds; wheat, broad bean and kidney bean. Interestingly, fraction no. 2 caused 100% inhibition of these isolated fungal species at 100μg/mL. The minimum fungicidal concentration (MFC) was estimated to be 50μg/mL against A. flavus and 40μg/mL for A. niger and P. griseofulvum. Generally, subjecting each of the tested isolates to fraction no. 2 led to damage in their DNA as shown by the comet assay. Gas chromatography- mass spectroscopy (GC-MS) profiling of fraction no. 2 showed 12 major compounds with diverse possible biological activities being antiinflammatory, insecticide, anticancer, antineoplastic antifungal, and antimicrobial.