Allantoin, a crystalline compound was isolated from the methanolic extract of Cleome viscosa and it was reported for first time from this plant. The structure of Allantoin was elucidated by single crystal XRD and it was further confirmed through FTIR and ESI-MS spectroscopy techniques. It was crystallized in monoclinic crystal system with the space group P2i/c. Electronic structure characterization of the isolated Allantoin was done through density functional theory calculation. The atomic charges, dipole moment, frontier molecular orbital and the electrostatic potential map of the molecule in the gaseous phase and in the active site have also been analyzed. The optimized geometry was used for molecular docking to identify the possible binding mode. Furthermore, the in vitro antibacterial activity of the isolated Allantoin against Gram-positive and Gram-negative bacteria was evaluated. Maximum Inhibitory Concentrations (MIC) of isolated Allantoin results showed 4 µg/mL for B. subtilis and 8 µg/mL for S. aureus, E. coli and K. pneumoniae.

Cleome viscosa L., a member of the family Cleomaceae, is a potential medicinal plant, known for several bioactive properties e.g. anticancer, antidiabetic, antioxidant, antiinflammatory, 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 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. The study highlights that the compound can be isolated in larger quantities as the plant is easily available across the tropics.