The methanolic extract and conessine isolated from the stem bark of
Holarrhena floribunda
(
Hf) were tested for their antibacterial activities on
Bacillus:
Bacillus cereus
,
Bacillus subtilis
,
Bacillus megaterium
and
Bacillus stearothermophilus
using the disc diffusion method. Phytochemical analysis of the crude extract and fractions was also conducted. The inhibition parameters of the crude methanol extract and the total alkaloid fraction were determined using the macrodilution method. The results showed that the crude extract, the total alkaloid fraction and conessine exhibited a significant antibacterial effect against all the strains studied. The antibacterial effect of conessine is almost similar to that of chloramphenicol used as reference. The ratio of the minimal bactericidal concentration (MBC) over the minimal inhibitive concentration (MIC) indicates the bactericidal effect of the plant. These results support common use of stem bark of
Hf and conessine isolated from
Hf in the treatment of some infectious diseases.
