Mmushi T MSc (Microbiology).pdf

ABSTRACT
The leaves of fifteen plant species were collected from the Lowveld Botanical Garden in
Nelspruit, Mpumalanga Province, South Africa. The collection was based on a list of
plants and their ethnopharmacological information provided by the Phytomedicine
Programme at the University of Pretoria. The dried leaves of the plants were powdered
and extracted using hexane, dichloromethane, acetone and methanol. The extracts
were screened for antibacterial activity against Mycobacterium smegmatis and
Rhodococcus erythropolis. The acetone extract of Milletia stulhimannii was the most
active, showing activity against Mycobacterium smegmatis and Rhodococcus
erythropolis with MIC values 0.13 and 0.08 mg/ml, respectively. Acetone extracts for all
plants had the lowest MIC values ranging between 0.11-1.25 mg/ml and 0.08-1.25
mg/ml for M. smegmatis and R. erythropolis, respectively. Milletia stulhimannii, Albizia
gummifera, Xanthocercis zambesiaca and Barringtonia racemosa extracts have shown
the greatest potential for anti-tubercolosis agents. These were all active against M.
smegmatis with an average MIC value of acetone extracts of 0.13 mg/ml. Apodytes
dimidiata was selected for the isolation of active compounds since its activity on
qualitative antibacterial activity assays was highly prominent on TLC plates in
comparison to the other plant extracts. Two compounds were isolated from A. dimidiata
but after purification, their MICs were above 2.5 mg/ml indicating a possible loss of
activity during purification. The preliminary NMR spectra analysis suggested that the
compounds were a long fatty acid and a triterpene. Future work is required to elucidate
the chemical structures of the latter compounds and to test the activity of these
compounds against Mycobacterium tuberculosis.
xvii