The Luo community of Kenya have traditionally used plants for treatment of various disease conditions,
some of which we now know to be caused by microbial infections. Some of these plants, namely Lannea
stuhlmanii, Carissa edulis, Combretum fragrans, Conyza sumatrensis, Ormocarpum trichocarpum, Sida
cuneifolia, Plumbago zeylanica, and Rhoicissus revoilii, were studied. Their ethanol extracts were
screened for their antimicrobial activity against Candida albicans, Escherichia coli, Staphylococcus aureus
and Bacillus pumulus.
Ethanolic root extract of C sumatrensis had good antibacterial activity against E. coli, while extracts of
C fragrans root bark, C edulis root, S. cuneifolia whole plant, R. revoilii tubers and leaf extract of C
sumatrensis in the same solvent had good activity against it. Activity against B. pumulus was observed in
all extracts except those of L. stuhlmanii bark and R. revoilii tubers. Good activity against S. aureus was
observed for C fragrans, S. cuneifolia and L. stuhlmanii.
R. revoihi, L. stuhlmanii, C fragrans and C edulis exhibited good antifungal activity against Candida
Combretum fragrans bark extract had the highest overall antimicrobial activity of all the different plant
extracts examined and was subsequently chosen for further studies. All its ethanol, methanol, ethyl
acetate and chloroform extracts were found to have significant antimicrobial activity.
Combretum fragrans bark powder was found to contain saponins, cardiac glycosides, free anthraquinones
(anthracene glycosides), tannins and flavonoids. However, it had no starch nor alkaloids.
The chloroform extract of C fragrans was subjected to column chromatographic separation and
sitosterol (with stigmasterol as a minor compound) was isolated and identified. Sitosterol was shown to
have antifungal activity against C albicans and antibacterial activity against Escherichia coli.
The results of this work would therefore appear to lend support to the traditional use of Lannea
stuhlmanii, Combretum fragrans, Conyza sumatrensis (tineasis), Plumbago zeylanica, and Rhoicissus
revoilii in disease conditions where microbial infections may be a factor. Use of growth enhancers like
Carissa edulis in combination therapy may be justified on the basis of their immune boosting activity.