The dried fruits of Ammi visnaga were subjected to Soxhlet extraction with water, followed by hexane and purified by column chromatography to yield Khellin (1). Oximation of 1 yielded khellin oxime (2), crystallized by slow evaporation from CH2Cl2:EtOAc (6:3), characterized by single-crystal X-ray diffraction method for the first time. The DNA binding affinities of the 1 and 2 have been appraised by examining their ability to bind to dsFSDNA with ultraviolet-visible and fluorescence spectroscopies, thermal denaturation and square wave voltammetry techniques. The binding constants of the both compounds with dsFSDNA are calculated by UV-vis measurements. The square wave voltammograms proved that both compounds bind to dsFSDNA by intercalative binding mode. Competitive studies with ethidium bromide (EB) have shown that 1 and 2 exhibit the ability to displace the DNA-bound EB indicating 1 and 2 bind to DNA with intercalation with EB for the intercalative binding site as a challenging displacement. (C) 2019 Elsevier B.V. All rights reserved.