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Antibacterial activity of Senna siamae leaf extracts
on Salmonella typhi
*Doughari J. H and
Okafor N. B
Department of Microbiology, School of Pure and Applied
Sciences, Federal University of Technology, P.M.B 2076,
Yola 64002 Adamawa State, Nigeria.
*Corresponding author. E-mail:
jameshamuel@yahoo.com.
Accepted 29
January, 2008 |
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The aqueous and organic leaf extracts of the plant Senna
siamae, traditionally used for the treatment of
infectious disease, were tested for their activity against
clinical isolates of Salmonella typhi using the disc
diffusion method. The ethanol extracts showed the highest
activity (zone of inhibition 10 ± 0.01 mm), followed by
acetone extracts (zone of inhibition 8 ± 0.01 mm), while the
aqueous extracts showed the lowest activity (zone of
inhibition 3.5 ± 0.01 mm) at 40 mg/ml concentration.
Preliminary phytochemical studies revealed the presence of
alkaloids, saponins, tannins and glycosides. The activities
of the extracts were comparable to those of ampicillin,
chloramphenicol, cotrimoxazole and ciprofloxacin antibiotics
(t-test; p < 0.05). The antibacterial activities of the
extracts against S. typhi did not change
significantly when treated at 4, 30, 60 and 100°C for 1 h,
but reduced significantly at pH 6 to 10. The MIC and MBC
values of the crude extracts (1 - 3 mg/ml) were comparable
to those of the tested antibiotics (0.3 - 1 mg/ml) (t-test;
p < 0.05). Preliminary purification of the ethanol extracts
with hexane, ethyl acetate, chloroform and n-butanol
showed that the ethyl acetate fraction possessed the highest
activity (zone of inhibition 15 mm), followed by n-butanol
fraction (zone of inhibition 2 mm), while the chloroform
fraction did not show any activity at 20 mg/ml.
Key words:
Natural bioactive compounds, Senna siamae,
antibacterial activity, antityphoid drug, Salmonella
typhi, enteric fever, antibiotics. |
