ABSTRACT
The study was conducted to assess the antibacterial activity of Phyllanthus amarus
(Schum and Thonn) extract against Salmonella typhi causative agent of typhoid fever
at the laboratories of the Departments of Chemistry and Theoretical and Applied
Biology of the College of Science, Kwame Nkrumah University of Science and
Technology, Kumasi. The objectives were to determine the highest yield of crude
extract of P. amarus using different proportions of water to ethanol and to determine
the sensitivity of Salmonella typhi to these. Three different extraction procedures
were carried out. In the first procedure, seven extraction setups each containing
different proportions of the two extract (water and ethanol) were used with 10g of the
plant sample. In the second procedure, eight setups were used for the two solvents.
Ten grams of both fresh and dry plant sample were extracted in two different 200ml
of water and in another two different 200ml of water; 20g of both fresh and dry plant
sample were again extracted. The same procedure was repeated using ethanol as the
solvent. In the third procedure, 10g each of fresh plant sample were boiled in 100ml
and 200ml of water for 30 minutes. A sensitivity test to determine the zones of
inhibition for the various plant extracts was done on Salmonella typhi isolated from
human. Results from the crude yield of P. amarus using water only had the highest
crude yield of 2.57g, followed by ethanol only which was 2.52g. The sensitivity
studies conducted on the fresh P. amarus indicated that aqueous extract of P. amarus
inhibited S. typhi to a zone of 5.00mm in 10g/200ml and 7.17mm in 20g/200ml.
Ethanol extract also recorded an inhibition zone of 2.67mm and 5.33mm in
10g/200ml and 20g/200ml respectively. Again, sensitivity studies using dry P.
amarus samples showed that the aqueous extracts recorded a zone of inhibition of
7.33mm in 10g/200ml and 13.50mm in 20g/200ml. Also ethanol extracts also
recorded an inhibition zone of 6.83mm in 10g/200ml and 10.50mm in 20g/200ml.
Significant differences were observed among the extracts and the control in both
10g/200ml and 20g/200ml concentrations (P<0.05). Aqueous and ethanol extracts of
P. amarus proved inhibitory to S. typhi.