Migration of Canadian and South African knowledge workers
Bibliographic record
Abstract
South Africa is a country of great diversity. Different climate zones and a host of different habitats make South Africa the perfect platform for rich floral diversity. This floral diversity lends itself to the study of natural products by discovering new natural drugs that can be used in the treatment of many illnesses. Studies into the antioxidant properties of plants that are used in traditional medicine are an important aspect of research to determine the rationale of the use of plants by traditional healers. Many neurodegenerative diseases, like epilepsy, Parkinson's and Alzheimer's diseases, are linked to oxidative stress. Antioxidants could play a major role as neuroprotective agents and could alter the progression of these diseases. Epilepsy is one of the world s most prevalent central nervous system disorders and affects more than seventy per one thousand children in South Africa. Most of these cases are people in rural areas of South Africa where communities rely on the use of traditional medicine. Cotyledon orbiculata L. var orbiculata (Haw.) DC. is widely used in traditional medicine to treat epilepsy and other central nervous system disorders. The need to screen these plants for activity and toxicity is very important to understand the complex mechanism of action in the treatment of patients. In this study the methanol extract and three different fractions of the methanol extract of Cotyledon orbiculata were used to test for antioxidant activity and toxicity towards neuroblastoma cells. The freeze dried leaves of Cotyledon orbiculata were extracted with methanol using a Soxhlet apparatus. The concentrated extracts were analysed using HPLC (high pressure liquid chromatography) and three major peaks were selected for isolation. Three assays were performed to assess the antioxidant activity and toxicity of the isolated compounds. The thiobarbituric acid assay (TBA) quantifies the extent of the inhibition of lipid peroxidation in rat brain homogenates by the isolated fractions. All of the samples were able to attenuate lipid peroxidation as seen from the results obtained from the TBA assay. The methanol extract showed the best attenuation of lipid peroxidation in the rat brain homogenate with fraction 1 and 2 showing greater attenuation of lipid peroxidation than fraction 3. The nitroblue tetrazolium assay (NBT) quantifies the ability of the fractions to scavenge superoxide radicals in a rat brain homogenate. All samples were able to scavenge superoxide radicals as indicated by the NBT assay. The methanol extract showed the best superoxide scavenging abilities in the assay whereas fraction 1 showed better scavenging abilities than fraction 2 and 3. The 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide assay (MTT) indicates the toxicity of the fractions towards neuroblastoma cells. The methanol extract and fraction 2 in the highest concentration of 10 mg/ml were the only samples that showed toxicity towards neuroblastoma cells. The molecular structure of a compound from fraction 2 was determined by using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and mass spectroscopy (MS). This compound was identified as diethyl malate. Diethyl malate is an artefact that is generated in HPLC procedures in the presence of malic acid (which naturally occurs in the leaves of Cotyledon orbiculata) and ethanol. The methanol extract of Cotyledon orbiculata has high antioxidant activity and could be due to the presence of malic acid in the leaves of the plant. The rationale in the use of Cotyledon orbiculata in the treatment of epilepsy could not be determined due to the isolation of an artefact, diethyl malate, obtained from the fraction. Further research should include methods to prevent artefact formation and purification of the samples that are obtained.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.011 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".