Determination of Phytochemicals and Antimicrobial Activity of Aqueous Stem Bark Extract of Boswellia dalzielii against Some Common Pathogenic Microorganisms

Abstract

Phytochemical screening by High Performance Liquid Chromatography (HPLC), Fourier Transformed Infrared Spectroscopy (FTIR) and Gas Chromatography- Mass Spectrometry (GCMS) of crude aqueous extract of stem bark of B. dalzielii was performed and its antimicrobial activity on Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Salmonella typhi and Candida albicans was evaluated. The result of HPLC analysis revealed 10 components with major ones at peaks 3, 2, 4, 5, 8 and 6 with peak areas of 33.43%, 13.75%, 13.43%, 9.35%, 8.53% and 8.50% respectively; FT-IR revealed 18 functional groups which included amines, amides, a,β–unsaturated aldehydes, ketones, alkanes, alkenes, alkynes, alkyl halides, aromatics, aromatic and aliphatic amines; while the GCMS revealed 9 compounds with major ones as n- Hexadecanoic acid, Stearic acid, 9-Hexadecenoic acid, 1,E-11,Z-13-Octadecatriene with peak areas of 39.40%, 24.28%, 23.38% and 7.73% respectively. The susceptibility test showed that the extract at 50mg/ml to 5mg/ml was active against all the test isolates with higher zones of inhibition of 19±0.00mm for S. typhi and 18±0.30mm for P. mirabilis and 18±0.41mm for P. aeruginosa at 50mg/ml concentration each. Resistance was observed in E. coli and S. pyogenes at 2.5mg/ml concentration. Similarly, lowest MIC values of 12.5mg/ml were obtained for S. typhi and S. aureus and 25mg/ml for C. albicans, P. Mirabilis and P. aeruginosa. K. pneumoniae, E. coli, S. pyogenes and E. faecalis had MIC values of 50mg/ml each. The MBC/MFC values did not exceed the corresponding MIC values by more than a factor of 2. Conclusively, stem bark of B. dazielii contains many antimicrobial active compounds which can be purified and used as precursors for new antibiotics.