Antimicrobial properties and acute toxicity evaluation of Pycnanthus angolensis stem bark

Abstract

The antimicrobial activity of Pycnanthus angolensis (Welw) (stem bark) used in ethnomedicine to treat urinary tract infections, diarrhoea, malaria and typhoid fever was investigated. Clinical isolates of Klebsiella spp, Proteus mirabilis, and type isolates including Candida albicans ATCC 7596, Escherichia coli ATCC 11,775, Pseudomonas aeruginosa ATCC 10,145, Staphylococcus aureus ATCC 1200 and Salmonella kintambo SSRL113 were used in the study. Agar well diffusion and broth dilution techniques were used to determine the antimicrobial activity and minimum inhibitory concentration (MIC), respectively. The results showed that the plant's ethanol extract was more active than the aqueous plant extract. Fractionation of the ethanol extract with n-hexane, chloroform, ethyl-acetate, acetone and methanol was carried out to obtain corresponding fractions. Antimicrobial activity testing of the fractions showed that the ethyl-acetate fraction exhibited the highest antimicrobial effect. Phytochemical analysis of the crude extracts and the various fractions revealed the varied contents of alkaloids, saponins, essential oils, tannins, glycosides and flavonoids, which are or can be largely responsible for the recorded antimicrobial effect. Acute toxicity studies performed on the ethanolic extract using albino rats indicated that the extract is non-toxic (LD50>5000 mg/kg body weight).

Keywords

• Pycnanthus angolensis
• Antimicrobial activity
• Phytochemical analysis
• Fractions
• Acute toxicity