RÉSUMÉ
Cleome viscosa L., a member of the family Cleomaceae, is a potential medicinal plant, known for several bioactive properties such as: anticancer, antidiabetic, antioxidant, anti-inflammatory, antimicrobial, wound healing, etc. Our study aimed to isolate a bioactive compound and assess its antibacterial activity. The crystal compound imperatorin was isolated and reported for the first time from the aerial parts of C. viscosa. The isolation was made using silica gel (100-200 mesh) column chromatography. The structure of imperatorin was investigated through single-crystal XRD, unit cell molecules, FTIR, and ESI-MS spectral analysis. The results validated imperatorin's triclinic crystal structure and P2i/c distance group. The electronic structure was also calculated (4.28/6.21 D) along with the frontier molecular orbital, dipole moment, atomic charges, and electrostatic map of particles in gaseous stage and active site. Imperatorin showed highest activity at 40 µg/mL concentration against Gram + ve bacteria: Staphylococcus aureus (3 ± 0.2 mm), Bacillus subtilis (3 ± 0.6 mm), and Gram -ve bacteria: Klebsiella pneumoniae (3 ± 0.2 mm), Escherichia coli (5 ± 0.2 mm). The study highlights that the compound can be isolated in larger quantities as the plant is easily available across the tropics.