Antibacterial Efficacy and Molecular Docking of Leaf Extract of Laurus nobilis L Against some Isolated Pathogenic UTI Bacteria

Abstract

The objective of the current study was to analyze the chemical compositions and antibacterial properties of Laurus nobilis. The bacterial strain was isolated from urine sample of female patients have urinary tract infection in Al-Basrah Teaching Hospital. Two solvents (hot and cold aqueous and ethanol) were used to extract the dried leaves of L. nobilis. While there were differences in the inhibition zones that solvent extracts demonstrated against bacterial pathogens, all of them significantly inhibited pathogens. The diameters of the inhibition zones on Staphylococcus aureus where the alcoholic extract was in the range of 17-29 mm, 22-28 mm for hot water and 12-14 mm for cold aqueous extract. The diameters of the inhibition zones on Klebsiella pneumoniae for alcoholic extract were 18-20 mm, 19-21.5 mm for hot aqueous extract and 12-17 mm for cold water extract. The GC-MS analysis demonstrated the presence of different phytochemical compounds in the extract of Laurus nobilis. A total of 60 compounds were identified, for ethanolic extract, tris (2-methylenecyclopropyl)methanol, (3aS,6aR,9aR,9bS)-3,6,9-trimethylenedecahydroazuleno[4,5-b]furan-2(3H)-one and (3aS,6aR,9aR,9bS)-6-methyl-3,9-dimethylene-3a,4,6a,7,8,9,9a,9b-octahydroazuleno[4,5-b]furan-2(3H)-one were the major compounds with percentage values 9.64%, 8.86% and 7.43%, respectively. For hot water extract, the major three compounds were 5-(hydroxymethyl)furan-2-carbaldehyde 11.64%, 2-methyl-5-nitro-2H-1,2,3-triazol-4-amine 8.39% and tris(2-methylenecyclopropyl)methanol 6.81%. Whereas, for cold water extract, the major compounds were n-Hexadecanoic acid 26.05%, Bis(2-ethylhexyl) phthalate 22.94% and Octadecanoic acid 8.25%. Molecular docking showed that these nine major compounds had an excellent binding affinity -4.25 to -8.56 kcal/mol against S. aureus using protein 1JIJ. The binding affinity of these compounds against K. pneumoniae (protein 6PIB) were in the range - 4.03 to -8.22 kcal/mol.