To investigate the in-vitro antimicrobial activities of the extracts of Abrus precatorius on some clinical isolates as resistance to available and affordable antibiotics by these pathogens is on the increase.
In this study the antimicrobial effects of the extracts of Abrus precatorius from leaves, stem and the seed oil were tested against Staphylococcus aureus ATCC 25923, three clinical S. aureus isolates from different sources, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus anginosus (S.milleri), Bacillus subtilis, Corynebacterium spp (toxigenic strain of the mitis biotype), Escherichia coli ATCC 25922, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa as well as Candida albicans using the agar well diffusion technique. Aqueous and methanolic extraction, using the soxhlet extractor was carried out on all plant parts used while petroleum ether was the solvent used to extract the seed oil. To measure the MIC values, various concentrations of the stock, 512, 256, 128, 64, 32, 16, 8 and 4 microg/ml were assayed against the test bacteria.
At the different concentrations of the extracts used (512 microg/ml - 4 microg/ml), Staphylococcus aureus was the most sensitive organism with an MIC of 8 ug/ml for the leaf extract. Extract from the stem and seed oil were potent against some of the gram-positive bacteria and Candida albicans but not against S anginosus, E. faecalis and gram-negative bacteria tested. The pH of the extracts ranged between pH5 and pH8. This study demonstrates that Abrus precatorius particularly the seed oil has a potent antimicrobial activity.
The results substantiate the ethno botanical use of different parts of Abrus precatorius for the treatment of various bacteria-related diseases. Topical application of Abrus precatorius extracts in ointments may be recommended especially for treating superficial infections caused by Staphylococcus aureus.