Antimicrobial activity of Androstachys johnsonii Prain

Extracts of leaf, root, bark and soil leachates of Androstachys johnsonii screened for antibacterial activity had a significant inhibitory effect on most Gram-positive bacteria tested. Gram-negative bacteria were resistant to most extracts. Of the Gram-negative bacteria tested, 1% leaf extract significantly inhibited the growth of all bacteria tested and both 1% root and bark extract inhibited only one bacterial strain. At the concentration of 1 mg/ml, soil extracts showed less inhibitory activity against the bacteria tested. The growth of three out of five Gram-positive bacteria was inhibited by leaf extracts. At 0.1 mg/ml, four Gram-positive bacteria were inhibited. In both 0.01 and 0.1 mg/ml of leaf extracts, all Gram-negative bacteria were uninhibited. Root extract did not inhibit the growth of four Gram-positive bacteria at 0.01 mg/ml and two Gram-positive bacteria at 0.1 mg/ml, but had a noticeably higher level of activity against all Gram-positive bacteria, than bark and soil extracts. From the results obtained in this study, we conclude that the crude extracts of A. johnsonii exhibit significant antibacterial activity. Key words: Antimicrobial activity, Androstachys johnsonii, bacteria.