MSc (Microbiology) / Department of Microbiology / BACKGROUND: Medicinal plants form an important part of the Southern African cultural
heritage. Indigenous populations, for example the Vha-Venda people, tend to use medicinal
plants in formulations rather than western medicines for health and survival. In order to certify
and give scientific credibility to the use of medicinal plants formulations used by Vha-Venda
people for the treatment of diseases, several assays were carried out. The present study was
aimed at assessing phytochemical content, antimicrobial, antioxidant and cytotoxic activities
of four indigenous Venda medicinal plants in a formulation and compare their activity with
each plant used individually.
METHODS: Peltophorum africanum (roots), Pterocarpus angolensis (bark), Terminalia
sericea (roots) and Ximenia caffra (roots) were collected from the Thohoyandou area. The
collected plant parts were extracted with methanol and water respectively. Individual plant
extracts and Five designed formulations were tested for their antimicrobial activity against
Staphylococcus aureus ATCC 25923 (Methicillin Resistant), Staphylococcus aureus ATCC
33591(Methicillin Susceptible), beta lactamase producing Klebsiella pneumonia (ATCC
700603) and extended spectrum beta lactamase producing E. coli (ATCC 35218), four clinical
isolates of Candida spp and Cryptococcus neoformans using the Broth dilution method.
Minimum bactericidal concentration (MBC) of the extracts was determined by culturing the
contents of minimum inhibitory concentration (MIC) on nutrient agar. Similarly, minimum
fungicidal concentration (MFC) was also determined by culturing contents of MIC in
sabouraud dextrose agar (SDA). Extracts were further assessed for their total phenolic content,
total flavonoid content and Qualitative phytochemical analysis. The antioxidant ability of the
plants extracts and formulations to scavenge free radical DPPH was also determined. The plant
formulations were assessed for their anti-HIV activity using the reverse transcriptase
colorimetric assay kit. Cytotoxicity against human lymphatic endothelial cells (HLEC) was
determined using MTT assay.
RESULTS: Methanolic and aqueous extracts of T. sericea exhibited the best antifungal and
antibacterial activities whilst P. angolensis and X. caffra showed poor activities. Methanolic
plant formulations showed good activities compared to aqueous formulations. However,
Fractional Inhibition Concentration Index showed that there was 1 synergistic interaction, 25
additive interactions and 14 antagonistic interactions between the plant extracts. The
methanolic formulation 3 showed the best overall phenolic content at 11.85±0.109 mgGAE/g
whilst aqueous X. caffra extract showed the least content at 4.546±0.104 mgGAE/g. Higher
total flavonoid contents were seen in methanolic formulation 4 at 2.75±0.02 mgQE/g.
Qualitative phytochemical analysis revealed the presence of flavonoids, phenolics, terpenoids,
tannins, saponins and steroids in 80% of the tested plant extracts and formulations. All plant
extracts and formulations exhibited good antioxidant activity against DPPH. The methanolic
formulation showed the best antioxidant activity with IC50 of 0.094 ± 0.33μg/ml. For anti-
HIV inhibition, all formulations at 200μg/ml exhibited higher percentage of HIV-1 reverse
transcriptase inhibition with methanolic mixture 3 being the best overall at 97.5% activity
whilst aqueous mixture5 was the least active with 63.03% inhibition activity. Moreover, the
best anti-HIV activity at 100μg/ml was exhibited by methanolic mixture 3 at 71% inhibition.
Furthermore, aqueous X. caffra, mixture 2 inhibited 26% and 51% at 12.5mg/ml and
3.125mg/ml respectively. Peltophorum africanum and mixture 5 inhibited 34%, 54% and 43%
at 3.125mg/ml, 6.25mg/ml and 12.5 mg/ml respectively of Human Lymphatic Endothelial cells
growth.
CONCLUSIONS: The results from the study indicated that most of the commonly used
traditional medicinal Plants in the Venda region when mixed together have merit for use in
traditional medical practice as they have shown good antimicrobial activities, good antioxidant
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activities, good phytochemical activities and good cell proliferation activity. However some
formulations showed antagonistic interaction against bacteria. Some Individual medicinal
plants showed toxicity at higher concentrations against immune cells. Whereas formulations
promoted cell proliferation, therefore, the use of such individual plants in the treatment of
infections should be highly monitored as they may pose a health threat to normal immune cells.
Generally, plants are potential pharmacological agents which needs to be preserved and
harvested with care. / NRF
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:univen/oai:univendspace.univen.ac.za:11602/1096 |
| Date | 18 May 2018 |
| Creators | Mboweni, Hlayisa Fredah |
| Contributors | Samie, A., Tshikalange, T. E. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | 1 online resource (viii, 131 leaves : color illustrations) |
| Rights | University of Venda |
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