IN-VITRO ANTIBACTERIAL ACTIVITY AND PHYTOCHEMICAL ANALYSIS OF LEAF EXTRACT OF VERBENA OFFICINALIS

The leaf of Verbena officinalis was collected, air dried under the shed, powdered, soaked in and extracted with 80% methanol. The crude extract was tested for it’s in-vitro antibacterial activity against S. aureus and E. coli using agar disc diffusion method. Antibacterial assay was made using extract concentrations of 250 mg/ml, 500 mg/ml, and 1000 mg/ml. The extract showed a concentration-dependent zone of inhibition against the test bacteria. The strongest activity (largest zone of inhibition, 20.38 mm) was obtained at the concentration of 1000 mg/ml against S. aureus. The minimum inhibitory concentrations (MICs) of V. officinalis against S. aureus and E. coli were determined to be 0.019 mg/ml and 0.313 mg/ml respectively. Phytochemical analysis was also conducted on the powdered leaf of the plant. Seven secondary metabolites including chromophores, polyphenols, saponin, phytosterols, flavonoids, cardiac glycosides and tannins were detected from this medicinal plant. The observed antibacterial activity could be attributed to the presence of these secondary metabolites which have been associated with varying degrees of antibacterial activities. In conclusion, the plant was found to exhibit an encouraging level of antibacterial activity. Further, studies are thus warranted to determine the antibacterial activities of the different chemical isolates of the plant. Also, in-vivo studies should be carried out to support these findings and to determine the safety and other pharmacokinetic profiles.