Pharmaco-chemical investigation of Erythrina caffra: extracts, isolated compounds and their biological activities
- Authors: Nogqala, Simnikiwe
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422459 , vital:71944
- Description: In this study, secondary metabolites isolated from Erythrina caffra, a medicinal plant indigenous to South Africa, were investigated. E. caffra is well-known for its healing properties and it is traditionally used for treating bacterial infections like tuberculosis (TB), abscesses, tooth aches and ear infections. Its extracts have also been used to treat cancer. Though many studies have been done on this plant, most of them tended to focus solely on the isolated compounds. In the present study however, extracts, fractions and isolated compounds from E. caffra were evaluated for their anticancer, anti-oxidant, anti-enzymatic, antibacterial and cytotoxicity. The methanol crude extract (B1) from the stem bark of E. caffra was used to extract alkaloidic fractions (B2 and B3) using ethyl acetate and n-butanol respectively, a third fraction (B4) was also extracted using ethyl acetate this fraction was called a neutral fraction. The neutral fraction (B4) was fractionated and through a sequence of column chromatography three active secondary metabolites were isolated. The isolated compounds included Lupeol (1), stigmasterol (2) and 5,7-Dihydroxy-4'-methoxy-3',5'-diprenylflavanone (3). These isolated compounds were characterized and identified using spectroscopic techniques including IR, NMR and high-resolution Mass Spectrometry. Using the cell line HCC-70, isolated from a primary ductal carcinoma, in vitro anticancer assays were carried out on the crude extract from the bark, fractions, isolated compounds and an unseparated mixture of two compounds. These samples were also evaluated for their anti-oxidant, anti-enzymatic, antibacterial and cytotoxicity activities. The crude extract inhibited the cell viability by over 30% and had no effect on the HeLa cells at concentrations of 20μM. Abyssinone V’ 4-methyl-ether (3) and the mixture of stigmasterol (2) and an unidentified compound exhibited potent anticancer activity against the HCC-70 cell line with IC50 of 18.05μM and 9.04μM respectively. Antibacterial assays were also carried out on the crude extracts, fractions and concoctions made from the fractions with the best activity combined with the ones that performed poorly. The concoctions were prepared as two separate series (S and N series). The crude extract inhibited more than 80% of the Staphylococcus aureus cells at a concentration of 20μM with only minimal damage to the HeLa cells. In the concoctions however, the N series managed to inhibit over 96% of the S. aureus while exhibiting no cytotoxicity towards HeLa cells. The extract and its fractions also showed good anti-oxidant activities. Molecular docking of these compounds was done on the Human estrogen receptor (PDB ID:3ERT) and Abyssinone V’ 4-methyl-ether (3) showed the best docking score of -6.6 Kcal/mol, for the simulation against Epidermal growth factor receptor (PDB ID: 1M17) Stigmasterol (2) showed the best docking score of -3.8 Kcal/mol. In silico docking on 3ERT and 1M17 were done to test the binding affinity of the isolated compounds to the proteins which are well known to be overexpressed in some types of cancer. Flavonoids isolated from Erythrina species have been reported to possess good antiplasmodial activity. However, due to the minute amounts isolated in the present study in-vitro assays could not be carried out. Nevertheless, in-silico assays were conducted on the most prominent protozoal parasite which causes malaria in the majority of African countries. In-silico simulations were done against Plasmodium falciparum protein (PDB ID: 7KJH), of the tested compounds Abyssinone V’ 4-methyl-ether (3) was found possess the best docking score of -4.4 Kcal/mol. The molecular docking of 7KJH was done to assess the inhibitory potential of the isolated compounds on protozoal parasites. Pharmacokinetic properties of the isolated compounds were also assessed in silico to assist in evaluating the drug likeness of these compounds. The compounds showed a percent human oral absorption of 100% except for Abyssinone V’ 4-methyl-ether (3), which showed 93.83%, this indicates a remarkable oral bioavailability. Stigamsterol (2) exhibited a Caco-2 cell permeability (QPPCaco) greater than 500 which indicates outstanding results for good intestinal absorption. The compounds also displayed a blood-brain partition co-efficient (QPlogBB) ranging from -1.433 to 0.128 suggesting they will have less potential to cross the blood-brain barrier, thus reducing any CNS related toxicity. Molecular networking of the crude extracts and the fractions was done through GNPS which allowed the identification of known compounds including one isolated in the present study, Abyssinone V’ 4-methyl-ether (3). Possible derivatives that have not been isolated from this plant before were also putatively identified. , Thesis (MSc) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-03-29
Prosecution of forced marriage by international courts and tribunals in light of the principle of legality
- Authors: Okeyo, Julian Rebecca Atieno
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/420720 , vital:71772
- Description: Thesis embargoed. Probable release date in 2024. , Thesis (LLM) -- Faculty of Law, Law, 2023
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- Date Issued: 2023-03-29
Analysis of corporate failures: a case study of two South African banks
- Authors: Mqomboti, Xitshembiso Pronacia
- Date: 2023-02
- Subjects: Business failures South Africa , Corporate governance South Africa , Risk management , Operational risk , Business ethics , Bank management South Africa , Banks and banking South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419151 , vital:71620
- Description: This study analysed the factors that contributed to the failure of Venda Building Society Mutual Bank (VBS) and African Bank Limited and the impact it had on their key stakeholders. The specific objectives of this study were to evaluate African Bank and VBS bank's operational risk management processes and controls, the role of ethical failures at VBS bank and African Bank; and assess how the failures affected their stakeholders. The population sample of the study included African Bank and VBS. The study adopted a qualitative research method. Existing reports from both African Bank and VBS were used to collect data. The study adopted a thematic data analysis method, which includes data coding and the development of themes. The data analysis framework was derived from a defined set of research propositions and seven (7) themes were derived from this analysis method. The failure in operational controls of both banks and ineffective risk management structures including unethical conduct by the executive management and board of VBS bank, irregular financial transactions and weakened external auditing function resulted in an unaccountable executive relationship and reckless lending decision-making. This research study will expand on the existing body of knowledge on the failures and near-failures of banks in the South African banking sector. The South African banking industry and its regulatory bodies will be better equipped to strengthen their corporate governance in risk controls to mitigate future collapses and near collapses of banks. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
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- Date Issued: 2023-02
Design and development of mobile-based e-Marketing application for communal farmers in Eastern Cape. South Africa.
- Authors: Fatumo, Dare Ebenezer
- Date: 2023-02
- Subjects: Food security , Agriculture , Agriculture -- Technology transfer
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27511 , vital:67421
- Description: The application of Information and Communication Technologies (ICT) in agriculture can augment farmers' production capabilities, this is a perception for all farmers worldwide, but there are some in communal areas who may not be as exposed to ICT tools as their commercial counterparts in urban areas, especially in developed communities. Food security in any society is a vital measure that should always be treated with high priority since humankind's existence is based on food availability. One major challenge with farmers in communal areas has been the marketing of their farm produce effectively to avoid wastage, get more value, and bridge the gap between themselves and urban commercial farmers. This challenge includes food wastage, untimely information, and market accessibility due to distance restraint. ICT can beused to bring a functional platform to assist this challenge. In this context, communal farmers have a challenge. The aim of this research was to design and develop an easy-to-use mobilebased e-marketing application for marketing farm products for communal farmers in Alice community, South Africa. Before design and development, review of challenges of farmers on the reception and communication of sensitive information pertaining to food security. Effective communication of farm produce baseline information on awareness and adaptation of mobile ICT technology of communal farmers was investigated. A mixed method was used through reviews of literature and as well distribution of questionnaires to get an understanding of the present state of communal farmers’ marketing problems. Furthermore, a prototyping methodology was used in the development of the mobile-based application for this research. The result of this research demonstrated the need for communal farmers to market their farm products at their convenience. An easy-to-use mobile-based e-market application was then developed; the application is an android application that will assist communal farmers in marketing their farm products as soon as they are available to avoid food wastage. The application performance and evaluation assessment indicated that the tool would maximize farm productivity and profitability and, facilitate concise and effective access to the market, as well as eliminate the need for an intermediary. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
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- Date Issued: 2023-02