Inhibitory And Antibiofilm Activities Of Methanolic Extracts Of Some Medicinal Plants Against Some Strains Of Pseudomonas Aeruginosa :-Ahukanna, Onyinyechi R

ABSTRACT xi resistant to conventional use of products from plant The prevalence of Pseudomonas aeruginosa strains that are antibiotics have been vastly studied over the years, and the origin that have demonstrated effective antimicrobial and antibiofilm activities have proven to be an effective source. In this study, methanolic extracts of Garcinia kola, Asystesia gangetica, Ficus exasperata, Chromolena odorata and Philiostigma thonningii were assayed for antibacterial and antibiofilm activities against strains of P. aeruginosa engineered to express various stages of biofilm formation. Different concentrations (10,5 and 2.5mg/ml) of the extracts were tested against the strains using agar well diffusion method. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the plant extracts were determined by the broth dilution method. Antibiofilm assay of the plant extracts were also performed, after which the potent plant extracts were subjected to column chromatography and thin layer chromatography. Fractions obtained were screened for antibacterial activity against the P. aeruginosa strains. The chemical constituents or compounds present in the potent fractions were delineated by Gas chromatographic and Mass spectrometric profiling (GC-MS). Results revealed that of the five plant extracts tested, F. exasperata and P. thonningii exhibited significant antibacterial activities producing zones of inhibition ranging from (11.0mm ± 1.41) against PAOI-L-wt to (13.0mm± 1.41) against PA01-W-GFP respectively. Extracts of G. kola, A. gangetica, and C. odorata showed low to no antibacterial activities. MIC and MBC values of the potent extracts ranged from 0.313 - 0.625mg/ml and 0.625- 1.25mg/ml, respectively. Antibiofilm assay showed that the extracts of F. exasperata and P. thonningii significantly inhibited biofilm formation for most ofthe P. aeruginosa strains used. Column and Thin layer chromatography ofF exasperata and P. thonningii gave six fractions each and antibacterial activities of fractions of F. exasperata revealed loss of activity suggesting synergistic activity ofthe extract, while fraction 5 of P. thonningii was active against most of the strains. The GC-MS analysis of fraction 5 of P. thonningii revealed the presence of four compounds: Methyl(2S)-6-[acetyl(methyl)]amino,24-Chloro25methoxylanost-8-en-3-yl-acetate, CylindrocyclophaneA and Nephthoside. CylindrocyclophaneA and Nephthoside are known for their anti-inflammatory and cytotoxic activities. Conclusively, extracts ofF. exasperata and P. thonningii exerted strong antibacterial and antibiofilm properties indicating their potential therapeutic value which can be used as an option in the treatment of biofilm associated infections caused by P. aeruginosa.