Bulbine natalensis
Baker has been acclaimed to be used as an antimicrobial agent in the folklore medicine of South
Africa without scientific evidence to substantiate or refute this claim. In view of this, the
in vitro antimicrobial activity of solvent
fractions (ethanol, ethyl acetate, n-butanol and water) from
Bulbine natalensis Tuber against 4 Gram positive and 12 Gram
negative bacteria as well as 3 fungal species were investigated using agar dilution. The ethanolic extract, n-butanol and ethyl
acetate fractions inhibited 75, 87.5 and 100% respectively of the bacterial species in this study. The ethanolic, n-butanol and ethyl
acetate fractions produced growth inhibition at MIC range of 1-10, 3-10 as well as 1 and 5 mg/ml respectively whereas the water
fraction did not inhibit the growth of any of the bacterial species. Again, it was only the ethyl acetate fraction that inhibited the
growth of
Shigelli flexneri
,
Staphyloccus aureus
and
Escherichia coli
. The ethanolic, ethyl acetate and n-butanolic fractions dose
dependently inhibited the growth of
Aspergillus niger
and
A. flavus
whereas the water fraction produced 100% growth inhibition
of the
Aspergillus species at all the doses investigated. In contrast, no growth inhibition was produced on
Candida albicans
. The
growth inhibition produced by the solvent fractions of
B. natalensis Tuber in this study thus justifies the acclaimed use of the
plant as an antimicrobial agent. The ethyl acetate fraction was the most potent.
