Mitragyna inermis is a useful medicinal plant used in traditional medicine in Africa. It is used to treat several infectious diseases such as fever, headache, wounds, diarrhea, dysentery, cholera, malaria and other diseases. Fresh leaves of the plant were collected, authenticated, garbled, dried, grinded and extracted using 95% methanol. The extract was used for the phytochemical screening and bacterial susceptibility using well diffusion method.
The result obtained from the study showed the presence of tannins, flavonoids, alkaloids, cardiac glycosides, carbohydrate and reducing sugars in the methanol leaf extract of Mitragyna inermis while saponin was absent. The extract showed antibacterial activity on Staphlococcus aureus, Escherichia coli and Klebsiella pnuemoniae with minimum inhibitory concentration of 50mg/ml, 50mg/ml, and 25 mg/ml respectively. The activity was concentration dependent having no effect on tested concentration of 35.5mg/ml and 75mg/ml on Staphlococcus aureus and E. coli while at 18.75mg/ml on K. pneumoniae. K. pnuemoniae was more susceptible to the extract. The extract was bactericidal at concentration of 100mg/ml on S. aureus and K. pnuemoniae while 200mg/ml on E. coli. Thus the study demonstrated the antibacterial activity of methanol leaf extract of Mitragyna inermis and some possible phytochemical constituents that may be responsible for its activity.
Key words: Methanol leaf extract, Mitragyna inermis, phytochemical screening, antibacterial activity