In vitro Antibacterial Activity of Aqueous Extracts of Bidens pilosa L. (Asteraceae) from Nigeria

Aims: The aim of this work was to investigate the in vitro antibacterial activity of aqueous extracts of different organs of Bidens pilosa.
Study Design: The design includes the extraction of crude extracts from the air-dried leaves, stems and roots samples of B. pilosa and the screening and determination of antibacterial activity of the extracts.
Place and Duration of Study: The leaves, stems and roots of Bidens pilosa were exhaustively extracted separately with double distilled water. The extracts were tested for the presence of secondary metabolites. The antibacterial activity of extracts was tested against some clinical and environmental isolates using agar-disc diffusion and broth-microdilution methods.
Results: The leaf extract exhibited significant inhibition on growth of the bacteria tested than the seed and root extracts. The mean zones of inhibition of the leaf extract ranged between (9.0±0.6 - 27.3±1.2) mm compared with (6.0±0.6- 11.7±0.6) mm and (6.0±0.6 - 16.3±0.6) mm for the seed and root extracts, respectively. The minimum bactericidal concentrations (MBC), 1.3 - >10 mg/ml was found to be equal or twice the minimum inhibitory concentrations (MIC), 0.6 - >10 mg/ml for the leaf extract and twice or greater for the stem and root extracts.
Conclusion: The activity of the aqueous leaf extract of Bidens pilosa provides the scientific justification for the use of this plant in traditional medicinal.