ANTIBACTERIAL ACTIVITIES OF CRUD EEXTRACT OF CROTON MACROSTACHYUS LEAVES AND PURE COMPOUND (METHYL LAURATE) ISOLATED FROM IT

Abstract

Croton macrostachyus Delil belongs to one of the largest genera of the family Euphorbiaceae, called Croton under the subfamily Crotonoideae. The genus Croton is ecologically prominent, and an important source of secondary metabolites with antimicrobial properties in tropics and subtropics. The objective of this study was to test the antibacterial property of the leaf extract of Croton macrostachyus and a lauric acid derivative, Methyl Laurate, isolated from it. Crude extract was obtained through phytochemical screening using the solvent acetone. The pure compound Methyl Laurate was isolated by a combined application of column chromatography, gel filtration using Sephadex LH-20 and preparative thin layer chromatography (prep-TLC) following crude extraction. Disk diffusion method was employed to assess antibacterial activities of both the crude and the pure compound on four bacterial strains viz Staphylococcus aureus, Escherichia coli, Salmonella typhi and Shigella boydii. MIC values were also determined for each. NMR data has confirmed that the isolated compound is a lauric acid derivative called methyl laurate. The crude extract, Croton Ethyl-acetate Extract (CEaE) showed strong antibacterial activities against Staphylococcus aureus and Shigella boydii with an MIC value of 6.25 mg/ml. However, the isolated compound, methyl laurate showed strong activities against all tested bacterial species with an MIC of 0.156 mg/ml (156 /ml) for Staphylococcus aureus, Salmonella typhi and Shigella boydii while 0.312 mg/ml (312 g/ml) for Escherichia coli. Results suggest that this plant contains phytochemicals that can combat pathogenic bacteria that might be the rationale for its traditional use in the external wound healing process.

Keywords: Antibacterial, Croton macrostachyus, Disk diffusion, Methyl Laurate , MIC