Imperatorin from the aerial parts of Cleome viscosa L.: a characterization study and evaluation of the antibacterial activity.

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.

Molecular Characterization of Mosquitocidal Toxin (Surface Layer Protein, SLP) from Bacillus cereus VCRC B540.

A marine Bacillus cereus (VCRC B540) with mosquitocidal effect was recently reported from red snapper fish (Lutjanus sanguineous) gut and surface layer protein (S-layer protein, SLP) was reported to be mosquito larvicidal factor. In this present study, the gene encoding the surface layer protein was amplified from the genomic DNA and functionally characterized. Amplification of SLP-encoding gene revealed 1,518 bp PCR product, and analysis of the sequence revealed the presence of 1482 bp open reading frame with coding capacity for a polypeptide of 493 amino acids. Phylogenetic analysis revealed with homology among closely related Bacillus cereus groups of organisms as well as Bacillus strains. Removal of nucleotides encoding signaling peptide revealed the functional cloning fragment of length 1398 bp. Theoretical molecular weight (51.7 kDa) and isoelectric point (5.99) of the deduced functional SLP protein were predicted using ProtParam. The amplified PCR product was cloned into a plasmid vector (pGEM-T), and the open reading frame free off signaling peptide was subsequently cloned inpET-28a(+) and expressed in Escherichia coli BL21 (DE3). The isopropyl-ß-D-thiogalactopyranoside (IPTG)-induced recombinant SLP was confirmed using western blotting, and functional SLP revealed mosquito larvicidal property. Therefore, the major findings revealed that SLP is a factor responsible for mosquitocidal activity, and the molecular characterization of this toxin was extensively studied.