Phytochemical Determinations and Antibacterial Activities of the Leaf Extracts of <i>Combretum molle</i> and <i>Gossypium arboretum</i>

Abstract

An investigation was carried out to screen the leaf extracts of Combratum mole and Gossypium arboreum for the presence of phytochemical components and antibacterial activity against Staphylococcus aureus strain OE5, Pseudomonas aeruginosa strain OE9, Klebsiella pneumoniae strain OE8 and Escherichia coli strain OE7 isolated from cases of otitis externa, using the agar diffusion procedure. The results indicated that the two medicinal plants contained alkaloids, tannins, saponins, anthracene, phenols and sesquiterpenes. Volatile oil was detected only in G. arboreum. The aqueous, ethanol and methanol extracts of the plants inhibited the growth of all the test organisms to varying degrees with the exception of E. coli, which was resistant to aqueous extract of C. mole. However, overall, the extracts of G.arboreum showed a higher degree of inhibition of the test bacteria than C.mole. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of G. arboreum and C.mole varied and ranged from 0.31mg/ml to 2.5mg/ml and 2.5mg/ml to 5.0mg/ml respectively. Synergistic effect of the ethanol and methanol extracts of the two plants resulted in enhanced antibacterial activity (large zones of inhibition, lower MIC, 0.31 – 1.25mg/ml, MBC, 0.63-2.5mg/ml).

Keywords: Extracts, inhibition, plants, pathogens, screening.