A comparative study of the in vitro antidiabetic properties, cytotoxicity and mechanism of action of Albuca bracteata and Albuca setosa bulb extracts
- Authors: Odeyemi, Samuel Wale
- Date: 2015
- Subjects: Medicinal plants Herbs -- Therapeutic use Diabetics -- Alternative treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/3154 , vital:28327
- Description: The search for cheap, non toxic and readily available antidiabetic drugs has been a challenge for researchers and the pharmaceutical industries. Diabetes mellitus is a metabolic disease characterized by defects in the synthesis of insulin and/or insensitivity to the action of insulin at the target cells. The disease has been on the increase mostly in developing countries where large proportions of the population have little access to good medical care due to either accessibility or non availability of synthetic drugs. This has led to the use of medicinal plants to treat diabetes because it is safe, cheap and with few side effects. There is little scientific evidence on the dosages, active compounds, mechanisms of action and toxicity of these traditionally used plants. Two of the most frequently used plants; Albuca setosa and Albuca bracteata were investigated in this study. The qualitative analysis of different extractions of these plants revealed the presence of phenolics, alkaloids, tannins and saponins. The antioxidant properties of aqueous, acetone and methanollic extracts of Albuca setosa and Albuca bracteata were investigated using models such as Diphenyl-1-Picrylhydrazyl (DPPH), 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), Ferric ion reducing antioxidant potential (FRAP), Nitric Oxide and Hydrogen Peroxide (H2O2). Both plants revealed inhibitions against DPPH in a concentration - dependent manner with Albuca setosa (0.330 mg/ml) showing higher activity than Albuca bracteata (0.647 mg/ml) determined from the IC50. The aqueous extract of Albuca setosa showed a higher inhibition against DPPH radical compared to the Albuca bracteata aqueous extract at all concentrations investigated. The isolated saponins from Albuca bracteata had a higher DPPH scavenging activity than the crude methanolic extract of the plant in a concentration - dependent manner but are significantly different from each other at 0.4, 0.6 and 1.0 mg/ml only. The IC50 of the saponins was also observed to be higher than the crude extracts and standards.The Albuca setosa aqueous extract showed a higher percentage inhibition of ABTS radicals than Albuca bracteata at all the concentrations investigated. Overall, the Albuca setosa aqueous extract (0.0809 mg/ml) showed maximum activity against ABTS radicals. The iron reducing power was significantly higher (P < 0.05) in the methanolic extract of both plants compared to the aqueous counterpart. Overall, the Albuca bracteata aqueous extract (0.344 mg/ml) showed maximum activity as indicated by the IC50. The aqueous extracts of both plants also revealed percentage inhibitions in a concentration - dependent manner against NO2. The aqueous extract of Albuca bracteata bulb was more active against nitric oxide and hydrogen peroxide inhibition. In this study, the cytotoxicity of the extracts was evaluated at a high dose of 100 μg/ml on Chang liver cells and determined using MTT, crystal violet, glucose consumption, lactate production and lactate dehydrogenase release and FRAP. The aqueous extracts of both Albuca setosa and Albuca bracteata were non-toxic on Chang liver cells at the concentrations investigated. The MTT revealed that the aqueous extract of Albuca setosa bulb had the optimum cell viability of 108.09 percent while the acetonic extract of Albuca bracteata showed the least cell viability (37.72 percent) compared with the control. The crystal violet test also revealed the acetone extract of Albuca bracteata to have the least percentage of cell viability at 31.47 percent, while the aqueous extract of Albuca setosa showed the maximum cell viability at 112.5 percent. The aqueous extracts of both plants showed higher percentage cell density on the second day of incubation from the proliferation assay. All the tested samples were observed to consume more glucose than the blank except for the methanollic and acetone extracts of Albuca bracteata bulb. The aqueous and methanolic extracts of Albuca setosa bulbs produced the highest lactate with 120.2 μg/ml and 113.7 μg/ml respectively. The acetone extracts of both Albuca setosa and Albuca bracteata revealed toxicity with a higher lactate dehydrogenase release compared to the control.
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- Date Issued: 2015
The role of civil society in advancing education rights : the case of Gadra Education, Grahamstown, South Africa
- Authors: Msindo, Esteri Makotore
- Date: 2015
- Subjects: Gadra Education (Grahamstown, South Africa) , Right to education -- South Africa , State departments of education -- South Africa , Educational change -- South Africa , Social justice -- South Africa , Civil society -- South Africa , Social contract
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3392 , http://hdl.handle.net/10962/d1016500
- Description: This thesis has identified and analysed the role of an NGO called Gadra Education in advancing education rights to the less advantaged people of Grahamstown in South Africa. Gadra Education’s role has been identified as twofold. Firstly as an educational NGO, Gadra Education’s initiatives directly impact on the lives of the less economically and socially privileged learners who, due to their previous learning environment in state schools, do not achieve academic results that ensure entry into tertiary level. Secondly its role is identified in its nature as an organisation that emerged due to the deficiencies in the state schooling system. It therefore stands de facto as a critical institution for critique of the state’s education system. The thesis concludes that without confronting the Department of Education or collaborating with it, Gadra Education offers a significant alternative approach which can potentially influence the state to improve the state schooling system. Its strategy of non-confrontation to the state, informal and non-corporatist is advantageous as an NGO that focuses on the actual provision of education. It focuses on instilling Ubuntu values of sharing and giving that are of critical significance in teaching and learning. The context of the thesis is located broadly within socio-economic rights and specifically on education rights. In South Africa where the state has not adequately met the educational obligations for the economically and socially less privileged citizens, the emergence of educational NGOs that focus on providing education to the poor is of vital importance. Although other NGOs that confront the state are important in pushing the state to deliver especially on school infrastructure, teacher deployment and other educational challenges, Gadra Education model ensures academic success for the learner. Lessons can be drawn from Gadra Education which can be potentially useful to state schools and other NGOs that seek to advance education rights to disadvantaged communities.
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- Date Issued: 2015