Preliminary Efficacy Assessment of Some Selected Indigenous Plant Species of Adamawa State, Nigeria on Salmonella typhi

Aims: To screened for phytochemicals and determine the in-vitro efficacy of the plants extracts on Salmonella typhi.

Study Design: Phytochemicals and in-vitro efficacy assessment of seven medicinal plants in comparison to the standard antibiotics.

Place and Duration of the Study: Department of Biological Science Technology, Federal Polytechnic Mubi, Adamawa State, between October to December, 2017.

Methodology: isolation and identification of the test organism; preparation of plants extracts; phytochemical analyses of the plants parts on aqueous extracts; in vitro susceptibility test (agar well diffusion assay),

Results: Of the thirteen (13) phytochemicals screened from seven (7) medicinal plants, none of the plants possessed all the bioactive components. However, the least possessing six (6) phytochemicals (Acacia sp) while the highest possessed nine components (Moringa oleifera and Carica papaya). Tannins and steroids were present in all the plant leaves while free anthraquinones were lacking in those leaves. The efficacy of the medicinal plants on the test organism was carried out by agar well diffusion method. At 50 mg/ml concentration, aqueous extracts of the plants leaves showed no inhibitory effect on S. typhi. However, at 100 mg/ml concentration, growth of S. typhi was inhibited variably with the highest zone (14 mm) produced by M. oleifera and Psidium guajava extracts. For acetone extracts, variable zones of inhibition were produced by the leaves of all the plants at both 50 and 100 mg/ml concentration with the highest zone (25 mm) produced by C. papaya at 100 mg/ml. Statistically, the zones of inhibition produced by acetone extracts at 100 mg/ml concentration was significantly higher than those produced by acetone extracts at 50 mg/ml (p=0.000) and aqueous extracts at 100 mg/ml (p=0.009). However, there was no statistical difference between zones of inhibition produced by aqueous extracts at 100 mg/ml and acetone extracts at 50 mg/ml on S. typhi (p=0.197). The result further showed that S. typhi was highly susceptible to ciprofloxacin at both 50 and 100 mg/ml with a zone of inhibition greater than those of the aqueous and acetone extracts. Synergy among the seven plants leaves was higher at 100 mg/ml concentration for both aqueous and acetone extracts. However, the acetone extracts of the combined plants leaves produced highest zones of inhibition on S. typhi than combined aqueous extracts at both concentrations. Interestingly, the synergy of the aqueous plants extracts at 50 mg/ml produced a relative antibacterial effect on S. typhi (10 mm) when compared to the individual plants which demonstrated the non-inhibitory effect.

Conclusion: These results upheld the traditional ideology of using these plants singly or combine in the management of typhoid fever.