ABSTRACT

The study evaluated the antimicrobial activity of Uziza leaf extract (Piper guineense) against food spoilage microorganisms. The plant materials of the Uziza leaf (Piper guineeense) were purchased locally from market in Ndoru, Ikwuano LGA of Abia State. The plant samples were identified by Dr. A.N. Osuagwu, department of Plant Health Management at Michael Okpara University of Agriculture, Umudike. The antibacterial activity of Uziza (Piper guineense) leaf extracts on some pathogens was investigated with different solvents (Ethanol and aqueous) against test organisms (Staphylococcus aureus, Esherichia coli and Proteus sp) using agar well diffusion method. The different extracts were prepared at different concentration (200mg/ml, 100 mg/ml, 50mg/ml, 25 mg/ml, 12.5 mg/ml and 6.25mg/ml). Amongst the different Uziza (Piper guineense) leaf extracts studied, the ethanolic extracts have more significant inhibitory effect than the aqueous extracts. The diameter zone of inhibition (mm) produced by ethanolic and aqueous leaf extract of the Uziza (Piper guineense) indicated that the aqueous extracts of Uziza (Piper guineense) showed minimal antibacterial activity against the isolates at 200 mg/ml, 100 mg/ml and 50 mg/ml concentrations as against the ethanolic extracts which showed antibacterial activity against the isolates at 200 mg/ml, 100 mg/ml, 50 mg/ml, 25 mg/ml and 12.5 mg/ml. The results also show that as the concentrations of the extract increases there is a corresponding increase in the zones of inhibition and comparing the activity, ethanolic extract of Uziza (Piper guineense) leaf exhibited higher antimicrobial activity against the test bacteria than aqueous extract. This difference may be due to the inhibitory ability of the ethanol even without extract, whereas the ability of the aqueous extract to exhibit this inhibition may be primarily due to its penetrative ability. From this study, it was observed that ethanol extracts exhibited better MIC on the test organisms. The antimicrobial effect of P. guineense contracts is attributable to the phytochemical constituents present in it. The P. guineense leaves are rich in phytonutrients such as flavonoids, tannins, saponins, glycosides and alkaloids. It can be concluded from this study that the leaf extracts of P guineense showed antimicrobial activity against the tested isolates. Therefore, the plant can be used in phytomedicine. It is recommended that further studies on more effective methods and other solvents for extracting only the necessary constituents as well as other processing and purification measures would be necessary.