ABSTRACT

Medicinal plants are traditional plants/herbs that have been used in healthcare centers to treat various types of illness. Examples of medicinal plants are Dogoyaro leaf, paw-paw leaf, e.t.c. Medicinal plants have a long history of use and their use is widespread in both developing and developed countries. The study evaluated the antibacterial effect of Dogoyaro (Azadirachta indica) leaf on pathogenic organisms. The fresh leaves of Dogoyaro (Azadirachta indica) leaves were collected at National Root Crop Research Institute Umudike in Ikwuano, Abia State, Nigeria. The plant was identified and authenticated at the Herbarium of the Department of Plant sciences and Biotechnology, Michael Okpara university of Agriculture, Umudike, Abia State. The antibacterial activity of Dogoyaro (Azadirachta indica) leaf extracts on some pathogens was investigated with different solvents (Ethanol and aqueous) against test organisms (Staphylococcus aureuas, Esherichia coli and Pseudomonas aeruginosa) 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 Dogoyaro (Azadirachta indica) 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 Dogoyaro (Azadirachta indica) indicated that the aqueous extracts of Dogoyaro (Azadirachta indica) showed minimal antibacterial activity against the isolates at 200 mg/ml, 100 mg/ml, 50 mg/ml and 25 mg/ml concentrations as against the ethanolic extracts. 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 neem 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 and MBC on the test organisms. The present work has shown that Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were susceptible to extracts of Dogoyaro (Azadirachta indica) which means the plant has antibacterial property. The results of this study suggest that the leaf of Dogoyaro (Azadirachta indica) can be used as an antibacterial agent against infections caused by Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa.