Evaluation of Antibacterial Activity of Six Ethnobotanicals Used in the Treatment of Infectious Diseases in Nigeria

Aristolochia bracteolata L. Ageratum conyzoides L. Calliandra portoricensis (Jacq.) Benth. Curculigo pilosa (Schum and Thonn) Engl. Gladiolus dalenii van Geel. and Securidaca longepedunculata Fresh. form an important part of traditional recipes used for the management of infectious diseases in Ibadan, Nigeria. This study investigated and compared the effectiveness of the six different ethnobotanicals in the management of bacterial infections to establish a scientific basis for their ethnomedical uses. The clinical bacterial isolates (1 x 10 1 x 10 cfu/ml) obtained from University College Hospital (UCH) were tested against 2 4 ethanol plant extracts (200 mg/ml) using agar well diffusion method. The powdered plant samples were analysed for the presence of various secondary metabolites viz. alkaloids, anthraquinones, cardinolides, saponins and tannins. The phytochemical screening revealed the presence of saponins in the six ethnobotanicals. Aristolochia bracteolata was the most active on Escherichia coli with 30.0 mm zone of inhibition at 1x 10 4 cfu/ml inoculum concentration. All ethanol plant extracts except S. longepedunculata showed significant (P<0.05) antibacterial activity against Streptococcus pyogenes. Four out of six ethnobotanicals were active on Klebsiella pneumoniae. Calliandra portoricensis, Curculigo pilosa and Gladiolus dalenii were most active on P. aeruginosa with 30.0 mm zone of inhibition at 1 x 10 cfu/ml. S. longepedunculata was inactive 4 against all isolates. Considering the various degree of antibacterial activity exhibited by the ethnobotanicals, it was concluded that A. bracteolata, A. conyzoides, C. portoricensis, C. pilosa and G. dalenii could be source of antibacterial agents. Isolation and identification of their active constituents could be necessary. Furthermore, toxicity test of the ethnobotanicals would confirm their safety in administration.