A comparative study of the antimicrobial properties of the ethanolic extracts of Landolphia owariensis leaf and root

The leaf ethanolic extract (LEEX) and root ethanolic extract (REEX) of Landolphia owariensis were comparatively subjected to phytochemical and antimicrobial screening. Susceptibility of some clinical isolates (Staphylococcus spp., Proteus spp. and Escherichia coli) to the extracts was determined using dehydrogenase assay method. The phytochemical screening indicated the presence of alkaloids, flavonoids, saponins and tannins in both the leaf and root extracts with cyanogenic glycosides present in the root extract only. The response of the bacterial strains to the leaf and root extracts was concentration dependent. Dehydrogenase activity was progressively inhibited by the root extract at a higher concentration range (150 - 2500 mu g/ml) than the leaf extract (20 - 2000 mu g/ml). LEEX gave an IC sub(50) of 20, 200, and 550 mg/ml against Staphylococcus spp., Proteus spp. and E. coli, respectively, while REEX gave an IC50 of 340, 320, and 1560 mg/ml against the organisms, respectively. The LEEX exhibited higher antibacterial activity than the REEX. Susceptibility of the organisms to the extracts showed: Staphylococcus spp. > Proteus spp. > E. coli. The observed antimicrobial properties could be due to the presence of alkaloid, flavonoids and tannins, which were identified in both extracts. The findings may be of clinical relevance and further substantiates the traditional use of L owariensis leaves and roots as antimicrobial agents.