The seed parts of the black mustard are traditionally used to treat different ailments beyond food in Ethiopia. This was promoted as a way to assess the constituents and bioassay activities of the seed parts of this plant through soaking with n-hexane and acetone consecutively. A reduced zone of inhibition against bacterial strains and a decreased antioxidant scavenging effectiveness are observed in the n-hexane-extracted crudes that were designated as fractions 1 and 2 by silica gel column chromatography. However, the black mustard seed that was soaked in acetone and eluted with a higher polarity index—designated as fraction 3—showed superior antioxidant activity (91.5%) as well as a larger zone of inhibition against E. coli (15.7 mm) and S. aureus (19.3 mm). Furthermore, fraction 3 contained a trace amount of zinc metals, which may enhance the antibacterial activity of the seed parts of the black mustard soaked with higher-polar solvents. In conclusion, the antioxidant and antibacterial activities displayed by the fractions containing zinc, which are soaked in higher solvents from the seed of black mustard, corroborate the traditional uses by the local people against various diseases.

Keywords: Traditional Medicinal Plants, Black Mustard, antioxidant activity and antibacterial activity