All six plants studied (Senna petersiana, Terminalia sericea, Cassine transvaalensis, Elephantorrhiza burkei, Rauvolfia caffra and Anredera cordifolia) proved to have considerable antibacterial activity. The water extracts of five of the six plants tested, showed activity against Bacillus pumilis, B. subtilis and Staphylococcus aureus respectively. Water extracts from S. petersiana showed a significant antibacterial activity by inhibiting all Gram-positive and two Gram-negative bacteria. A cytotoxicity assay of three plants (S. petersiana, T. sericea and A. cordifolia) on primary vervet monkey kidney ceelsl showed that A. cordifolia was the least cytotoxic extract with an ID50 value of 1.560 mg/ml. Both S. petersian and T. sericea showed an ID50 value of 0.024 mg/ml. Cytotoxicity as determined in this study does not necessarily mean that the active compound which can be isolated from these plants will also be toxic. Antiviral activity of S. petersiana, T. sericea and A. cordifoli crude extracts were investigated against herpes simplex virus type I at the non-toxic concentrations. Both T. sericea and A. cordifoli extracts showed to be non-active against HSV -I, but S. petersiana showed a 20 % reduction in replication of the virus after the sixth day of the experiment. Because of the sensitivity and instability of compounds in the root extract of S. petersiana, it was very difficult to isolate any pure compound. Bioassay-guided fractionation of the seeds of S. petersiana resulted in the isolation luteolin. Its structure was identified and confirmed through spectroscopic methods including IH, BC, UV, HMBC and HMBQ. An antibacterial assay of luteolin isolated from the seeds of S. petersiana showed activity against Baccilus cereus, B. pumilis, Streptococcus aureus and Staphylococcus areus at the concentration of I mg/ml. In the assay to assess the possible antiviral activity of luteolin against herpes simplex type I virus, 50% of the virus was inactivated at the concentration of 250 μg/ml. The results of this study have shown that it is possibl4e that the extracts studied, can provide humankind with valuable agents of potential use in the treatment of herpes and some bacterial species. / Dissertation (MSc ( Plant Physiology))--University of Pretoria, 2006. / Plant Science / unrestricted

Thesis (MSc. (Microbiology)) -- University of Limpopo, 2019 / The emergence of drug resistance to the first line drugs complicates the treatment of tuberculosis (TB), especially in parts of sub-Saharan Africa where accessibility to quality health care is limited. The search for alternative medication has been the centre of research for years due to challenges posed by infectious organisms including drug resistance, lengthy treatment periods and lack of quality health care in developing countries. Stomatostemma monteiroae is used in traditional medicine to treat TB and related symptoms. The aim of this study was to isolate and characterise compounds with antimycobacterial activity from Stomatostemma monteiroae. The plant materials were collected from Ga-Madiga village in Limpopo province of South Africa. Different plant parts namely: leaves, twigs, roots, tuber and tuber-peels were separated, washed, dried and milled to a fine powder. Several solvents (n-hexane, dichloromethane, acetone and methanol) were used to extract the plant material using various extraction methods such as maceration, defatting, and extract enrichment procedure and phytochemical analysis was done using standard chemical tests and thin layer chromatography. The qualitative antioxidant activity was determined by the thin layer chromatography (TLC) based 2,2-diphenyl-1picrylhydrazyl (DPPH) free radical scavenging activity and quantitative antioxidant activity was determined using colorimetric DPPH free radical scavenging and ferric reducing power assay. Antimycobacterial activity of the extracts was assessed using bioautography and micro dilution method tested on Mycobacterium smegmatis (ATCC 1441), Mycobacterium tuberculosis (ATCC 25177) and M. tuberculosis H37Rv (ATCC 27294). The cytotoxic effects of the extracts were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on Vero monkey kidney cells. The compounds with antimycobacterial activity were isolated using bioassay-guided fractionation and purified using preparative thin layer chromatography and thereafter identified using NMR spectroscopy to elucidate the structure. Various phytochemical constituents were detected in different plant parts, with the leaves and twigs possessing more of the phytoconstituents analysed. The TLC profile of S. monteiroae indicated that more compounds are non-polar to intermediate in polarity. The antioxidant activity analysis on TLC plates indicated that all the plant parts have low antioxidant activity, this was also confirmed by xxii quantitative tests. The leaves of S. monteiroae had antimycobacterial activity when analysed using bioautography, while other plant parts had no active bands. The minimum inhibitory concentration values were much higher than the positive control rifampicin and the roots (0.31 mg/mL) followed by the leaves (0.83 mg/mL) had lower inhibitory concentrations when tested against M. smegmatis. The MIC values of extracts against TB causing strains varied greatly, the leaves and the roots had even higher MIC value. Toxicity analysis indicated that all plant parts were non-toxic towards Vero cells (LC50 > 0.02 mg/mL). Bioassay-guided fractionation enabled isolation of one antimycobacterial pure compound from the leaves extracts. The isolated compound was identified using NMR and was found to be a sitosterol derivative 8,9-dehydro-4-methyl-24-vinylobtusifoliol. This compound had a noteworthy activity against M. smegmatis. The present study validates the use of S. monteiroae in the treatment of TB related symptoms traditionally. Further studies are required to analyse the cytotoxic effects of the isolated compound and also testing the antimycobacterial activity of the isolated compound on TB causing pathogens. / National Research Foundation (NRF)

Department of Botany / MSc(Botany)

MSc (Botany) / Department of Botany / See the attached abstract below

Thesis (Ph.D. (Biochemistry)) -- University of Limpopo, 2021 / Cancer remains one of the leading causes of morbidity and mortality worldwide with an estimated 9.9 million deaths in 2020. Cancer treatment regimens such as chemotherapy and radiotherapy have over the years fallen short due to drug resistance, toxicity, damage to normal healthy cells and tissues surrounding the treatment area. Moreover, they have shown very limited survival benefits for most advanced staged cancers such as colorectal cancer, which in 2020 was responsible for 3 728 deaths with a 6.8% incidence rate. Despite the many efforts in developing alternative chemotherapeutic strategies, cancer of the colon and cancer, in general, remains a burden. For centuries, plants and plant derivatives have been exploited for their nutritional and medicinal properties and now serve as chemical scaffolds or templates for designing and synthesising products with pharmacological importance. Herbal medicines are claimed to enhance therapeutic effects and are often used in combination with chronic medication. However, the concurrent use of herbal medicines and synthetic drugs may affect the pharmacokinetic profile of therapeutic drugs or trigger unexpected and undesirable effects. This study aimed to characterise the leaf extracts (crude water and crude methanol) of Momordica balsamina and investigate their potential anticancer activity on HT-29 colon cancer cells. The study also aimed to asses the effect of the extracts on drug metabolising enzymes (CYP450), specifically those which metabolise 5-Fluorouracil (5-FU) prodrugs or are inhibited by 5-FU since it is one of the first-line treatments for colon cancer. Dried powdered leaves were extracted using water and absolute methanol to obtain crude water and crude methanol extracts, respectively. For characterisation, the extracts were spotted on thin-layer chromatography (TLC) plates and further screened using chemical tests. The ferric ion reducing power assay and Liquid chromatographymass spectrometry were used to determine the antioxidant activity of the extracts and to identify prominent or abundant compounds in each extract, respectively. To assess the cytotoxic effect of the extracts and 5-FU, HT-29 colon cancer cells and C2C12 muscle cells, which were used as a model for normal cells, were exposed to concentrations that ranged from 0 to 2000 µg/ml for the water (H2O) extract, 0 to 300 µg/ml for the methanol (MeOH) extract or 0 to 100 µg/ml of 5-FU for 24 and 72 hours, and subjected to the MTT assay. The effect of the extracts on the efficacy of 5-FU was xxi assessed using the MTT assay by combined treatments of the extract and 5-FU. Genotoxicity of the extracts was assessed on the C2C12 cells using the Muse™ MultiColour DNA Damage kit. The generation of intracellular reactive oxygen species (ROS) was assessed by flow cytometry using the DCFH-DA assay. The JC-1 and acridine orange (AO)/propidium iodide (PI) staining assays were used to assess the effect of the extracts on the mitochondrial potential as well as cell and nuclear morphology, respectively. Apoptosis was quantified by flow cytometry using annexin V/PI and caspase activation assessed using the Caspase-8 and Caspase-9 colourimetric assay kits. The pro-apoptotic mechanism(s) was determined by assessing the expression profiles of selected apoptosis regulatory proteins using the human apoptosis antibody array kit. Cell cycle analysis by flow cytometry was conducted to determine the effect of the extract on the cell division cycle. Moreover, to determine the potential of herb-drug interactions, the Vivid® CYP450 Screening kits and P-gp-GloTM Assay Systems with P-glycoprotein were used to assess the effect on the activity of drug metabolising enzymes and drug transportation, respectively. The results showed that the MeOH extract possessed fewer polar compounds, higher ferric iron-reducing power, and a relative abundance of flavonol glycosides, cucurbitane-type triterpenoid aglycones, and cucurbitane-type glycosides than the H2O extract. The MeOH extract was further selectively cytotoxic to the HT-29 colon cancer cells at 24 hours of treatment and selectively induced genotoxicity in HT-29 cells. The H2O extract, however, was not cytotoxic to the HT-29 cells at all the tested concentrations at 24 and 72 hours of treatment. Analysis of nuclear and cell morphology suggested that the decrease in the percentage viability of MeOH extracttreated cells was associated with apoptotic cell death. Apoptosis was further confirmed by the loss of mitochondrial potential, increase in ROS production, caspase-8 and -9 activities as well as Annexin-V/PI-stained cells. Cell cycle analysis revealed cell cycle arrest at the S phase in MeOH extract-treated cells. Analysis of protein expression profiles revealed that the extract modulated various proteins that play a role in the promotion or inhibition of apoptosis. Moreover, the MeOH extract was shown to inhibit the activity of CYPs 1A2, 2A6, 2C8, and 2C9, while the H2O extract showed no significant inhibitory effects on the activity of all tested CYPs and 5-FU only significantly inhibited the activity of CYP2C9. However, combinatory treatments with 5-FU and the MeOH extract were shown to have no additive or diminishing effects on the efficacy of 5-FU on the activity of all the tested CYP enzymes. Treatment with 5FU (0.008 – 32 μg/ml) and the H2O extract (0.02 – 200 μg/ml) was shown to stimulate the ATPase activity of P-gp, while the MeOH extract significantly inhibited its activity with concentrations of 0.2, 2, and 20 μg/ml. In conclusion, the MeOH extract selectively induced cancer cell toxicity, genotoxicity as well as S phase cell cycle arrest and apoptosis via the intrinsic and extrinsic pathways. The anticancer activity of the MeOH leaf extract of M. balsamina as well as its antioxidant potential may be attributed to the presence and relative abundance of flavonol glycosides, cucurbitane-type triterpenoid aglycones, and cucurbitane-type glycosides. Although the MeOH extract may potentially reverse the effects of P-gp multidrug resistance by decreasing its activity, its inhibition of the activity of CYPs 1A2, 2A6, 2C8 and, 2C9, which are involved in the metabolism of more than 80% of the drugs in clinical use may suggest that co-administration of the MeOH extract may still result in increased plasma levels of drugs, thereby resulting in toxicity. The H2O extract, although not pro-apoptotic as the MeOH extract may still have the potential to be developed as a nutraceutical as it was shown to exhibit no adverse drug interactions and because this species is known to possess a wide variety of nutritional and medicinal values. / South African Medical Research Council (SAMRC) Research Capacity Development Initiative.

Thesis (M. Sc. (Botany)) -- University of Limpopo, 2018 / The aim of the study was to investigate medicinal plants used for the treatment of various ailments by the traditional healers and local people and to determine antifungal activities against animal fungal pathogens. Ethnobotanical survey was conducted to identify medicinal plants used by local people and traditional healers to treat various ailments in Makhado Local Municipality, Vhembe District, Limpopo, South Africa. A questionnaire was designed to gather information on the local name of plants, plant parts used and the methods of preparation and administration by the traditional healers. In our findings, sixty-three medicinal plants belonging to thirty-three families were identified to be used for treatment of various diseases such as chest complaint, sexual transmitted infections, headache, swollen legs, hypertension, blood purification, asthma, and infertility. Specific parts of the plant used for medicinal purposes vary from species to species and from one traditional healer to another. The dominant families were Fabaceae, Celastraceae and Euphorbiaceae. Of the sixty-three plants species identified, trees were the most predominant plant form (53%), followed by shrubs (23%), herbs (14%), and climbers (10%). Root, fruit, bark, leaves, seeds and in some instances the whole plant are used for the preparation of medicine while decoction and infusion were the general methods of preparation. The mode of administration of medicine was mainly oral. The most frequently used plant species were Warbugia salutaris (Bertol.f.) Chiov, Sclerocarya birrea (A.Rich) Hochst and Eleondron transvaalense (Burtt Davy) R.H. Archer. Eight plant species (Asparagus buchananii Bak., Albuca seineri (Engl. & K.Krause) J.C Manning & Goldblatt, Elephantorrhiza elephantina (Burch.) Skeels, Indigofera circinnata Benth, Maerua juncea Pax, Pentarrhinum insipidum E. Mey., Senna italica Mill. and Schinus molle L.) were selected based on the information given by the local people and the traditional healers for further phytochemical analysis and microbiological assays. Antifungal activities of the selected plant species were determined against three fungal pathogens namely, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus. Of the tested plant species, hexane leaf extracts of M. juncea, ethyl acetate leaf extracts of S. italica, A. buchananii and E. elephantina were the most active against Candida albicans, Cryptococcus v neoformans and Aspergillus fumigatus with Minimum inhibitory concentration (MIC) values ranging between 0.02 mg/ml and 0.08 mg/ml. Bioautography assay was used to determine the number of active compounds in the plant extracts. No active compounds were observed in some plant extracts against the tested animal fungal pathogens indicating possible synergism. The most promising plant species were: A. buchananii, A. seineri and M. juncea, all had shown good activity with 4 compounds against A. fumigatus. Acetone and methanol extracts had the same active compounds visible on bioautograms. Most of the active compounds were observed in TLC chromatograms developed Benzene: ethanol: ammonia hydroxide (BEA) eluent solvent system. Based on excellent antifungal activity against the tested microorganisms, leaf extracts of A. buchananii, A. seineri M. juncea, P. insipidum and root extracts of I. circinnata were also tested for cytotoxicity against the Vero kidney cells. All plant extracts investigated were relatively not toxic against the cells with LC50 ranging between 0.131 mg/ml and  1 mg/ml. Water extracts of A. buchananii, A. seineri and M. juncea had LC50  1 mg/ml. The leaf aqueous extracts of P. insipidum were less toxic than root aqueous extracts of I. circinnata with LC50 of 0.65 mg/ml and 0.49 mg/ml against the Vero kidney cells respectively. The results indicate that the local people and traditional healers in Makhado Local Municipality use medicinal plants and their indigenous knowledge on the treatment of fungal infections and related ailments. / University of Limpopo and National Research Foundation (NRF)

Thesis (MSc (Physiological Sciences))--University of Stellenbosch, 2006. / This study aimed to assess the effect of mild psychological stress in male Wistar rats using incremental, intermittent stress on parameters of atrophy, including body mass, soleus and extensor digitorum longus (EDL) muscle mass, and mechanisms possibly contributing to atrophy. Serum corticosterone concentrations, 20s proteasome activity, glutamine synthetase (GS) and tyrosine amino-transferase (TAT) activities were determined. I also assessed whether Sutherlandia (Su) or resistance exercise was able to reverse the effects of stress on any of these parameters.

Thesis (MScConsEcol(Conservation Ecology and Entomology)--University of Stellenbosch, 2009.

The use of traditional medicine through the use of medicinal plants in Africa and especially in South Africa has long been considered an important characteristic of people's daily lives and socio-cultural heritage. Cotyledon Orbiculata is among the medicinal plants that are used by South African traditional practitioners for the treatment of epilepsy and painful conditions such as corns, warts, toothache, earache, boils and various other ailments. However, the claim of therapeutic successes of medicinal plants by traditional medicine practitioners are hardly subjected to scientific scrutiny. This study therefore, investigated the anti-epileptic property of Cotyledon Orbiculata by studying the effects of the methanol extract of the plant against chemically induced seizures by pentylenetetrazole, picrotoxin, bicuculline and N-methyl-DL-aspartic acid in mice. The study also investigated the analgestic effects of Cotyledon Orbiculata by studying the effect of the plant extract on pain induced by acetic acid and hot plate thermal stimulation.

Medicinal bulbs form part of the diversified flora in South Africa. The plants are used extensively in South African traditional medicine in the treatment of various ailments. Due to the ever-increasing demand and the unrestricted collection of medicinal plants from the wild, many of these slow growing bulbous plant species are driven into over-exploitation and extinction. The main parts collected for use are the underground bulbs, leading to the destructive harvesting of the whole plant. This form of plant harvesting poses threats to the long term sustainability of these plant resources from their natural habitats. Sustainable harvesting of these plants should be within the limits of their capacity for self-renewal. However, this seldom occurs with the often inconsiderate medicinal plant gatherers. Conservation of these plants is therefore necessary. A strategy that would take into consideration the sustainable harvesting and perhaps simultaneously provide similar medicinal benefits, would be the substitution of bulbs with leaves of the same plant. This study was aimed at evaluating the seasonal pharmacological and phytochemical properties in bulbs/corms and leaves of medicinal bulbs with a view of promoting the substitution of bulbs with leaves in traditional medicinal use. Four medicinal bulbous plants, Tulbaghia violacea, Hypoxis hemerocallidea, Drimia robusta and Merwilla plumbea were evaluated for the pharmacological and phytochemical properties in their bulbs/corms and leaves in spring, summer, autumn and winter seasons, with a view of promoting the use of leaves as a conservation strategy. Dried plant materials were sequentially extracted with petroleum ether (PE), dichloromethane (DCM), 80% ethanol (EtOH) and water in each season. The extracts were tested for activities against Gram-positive (Bacillus subtilis and Staphylococcus aureus), Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria and the fungus Candida albicans using the in vitro microdilution assays to obtain minimum inhibitory concentrations (MIC) and minimum fungicidal concentrations (MFC). The four plant species were also evaluated for their ability to inhibit cyclooxygenase (COX-1 and COX-2) enzymes. Spectrophotometric methods were used to evaluate saponin and phenolic contents of samples from the four plant species in each season. Antibacterial activity was fairly comparable between bulbs/corms and leaves of H. hemerocallidea, T. violacea, and M. plumbea, with at least one extract showing some good activity (MIC < 1 mg/ml) in most of the seasons. Bulb extracts of D. robusta did not show good antibacterial activity while the leaf extracts showed good activity (0.78 mg/ml) against B. subtilis in spring, summer, and autumn and S. aureus (0.78 mg/ml) in autumn. The best antibacterial activity was recorded in winter, with MIC values as low as 0.195 mg/ml from the DCM bulb extracts of T. violacea against K. pneumoniae and S. aureus and PE corm extracts of H. hemerocallidea (0.195 mg/ml) against B. subtilis. Good antibacterial activity from water extracts were only recorded from corm extracts of H. hemerocallidea in summer, autumn and winter, H. hemerocallidea leaf extracts in autumn and winter, and M. plumbea bulb extracts in autumn. The leaf extracts of all the screened plant species demonstrated good fungicidal activity in autumn, with H. hemerocallidea corm water extracts recording an MFC value as low as 0.39 mg/ml. The leaf extracts of H. hemerocallidea (water), D. robusta (DCM) and M. plumbea (DCM) had good MFC values of 0.78 mg/ml each, in spring. The DCM leaf extracts of T. violacea also showed good fungicidal activity (0.78 mg/ml) in summer, while corm water extracts of H. hemerocallidea had an MFC value of 0.39 mg/ml in winter. There were no fungicidal activities recorded from all the bulb extracts in all the seasons. All the PE and DCM extracts in all the tested plant samples recorded between moderate (40-70%) and high (> 70%) COX-1 and COX-2 inhibition levels across all seasons. The EtOH corm extracts of H. hemerocallidea also demonstrated moderate to high inhibitory activity against COX-1 enzyme across all seasons. Bulb and leaf extracts of T. violacea showed selective inhibitory activity for COX-2 enzyme in all the seasons. The highest COX inhibitory levels were recorded in COX-2 from the PE leaf (spring) and bulb (autumn) extracts of T. violacea, with both recording 100% inhibitory activity. Phytochemical analysis revealed higher total phenolic compounds in bulbs/corms and leaves of all the analysed plant species, to be either higher in spring or winter. Plant material collected in autumn had the least levels of total phenolics. An almost similar trend to that of total phenolics was observed for flavonoids, gallotannins and condensed tannins in most plant samples, with higher levels either in spring or winter. Total saponins were consistently higher in winter than in the other seasons in all the screened plant species. There were in some cases, relationships between the peaks in the levels of some phytochemical compounds and the observed levels of bioactivity in different assays. The results obtained from this study demonstrate that the leaves of the screened plant species may substitute or complement bulbs in the treatment of certain ailments in traditional medicine. Thus, plant part substitution can be sustainably utilised in the conservation of these plant species while retaining the same medicinal benefits. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.