Aminoisoflavones are synthetic derivatives of a group of natural products found in plants and dietary components such as soya derived products. Three novel aminoisoflavones have been prepared via nitration of the parent isoflavone followed by reduction using tin (II) chloride dihydrate. These unstable aminoisoflavones were then conjugated with L-alanine, to give stable derivatives. The instability of the parent suggested that these conjugates could be used in chromogenic media to detect L-alanyl aminopeptidase producing Gram-negative bacteria, as cleavage of the amide would result in decomposition and the production of colored compounds. However, biological evaluation with a series of bacteria were conducted, although a simpler o-aminophenol conjugate did give black colonies with Escherichia coli strains on doped agar plates.