Antibacterial, Antifungal and Phytochemical Screening of Bitter Stem Bark (Sacoglottis gabonensis)

Abstract

The antimicrobial effects of bitter stem bark (Sacoglottis gabonensis) was evaluated using both ethanol and aqueous extracts against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Penicillium spp.  Agar-well diffusion method was employed in determining the antimicrobial activity and broth dilution method for determining the Minimum Inhibitory Concentration. All the isolates investigated were susceptible to both the ethanol, aqueous and the combined aqueous and ethanol (synergy) extracts of the bitter stem bark. The zone of inhibition ranged from 7.0 +0.00b mm to 13.0 +0.01a mm with Escherichia coli being the most susceptible at 13.0 +0.01a mm to the ethanol and at 12.0 +0.02a mm to the aqueous extracts at 200mg/ml concentration while P. aeruginosa and Penicillin spp. were the least susceptible at 11.0 +0.02a mm to the ethanol and at 10.0 +0.02a mm to the aqueous extract at 200mg/ml concentration. The control/ standard antimicrobial agent (Gentamicin and Ketoconazole) showed higher inhibitory activity than the plant extracts. The least inhibitory (MIC) value of 6.25 mg/ml was produced against P. aeruginosa by the ethanolic extract and against C. albicans by the combined (aqueous and ethanol) extract of the plant. The qualitative and quantitative phytochemical screening of the stem bark of Sacoglottis gabonensis reveals the presence of flavonoid, tannin, saponin and alkaloid. The most abundant percentage composition observed was falconoid (7.61 %) while tannin had the least component (1.26 %). The findings from this study show that the stem bark extract possesses appreciable antimicrobial activity against commonly encountered microorganisms in the environment. This therefore implies that it can be used as a chemotherapeutic agent which will contribute to the development of antibiotic drugs against the test organisms.