Browsing by Author "Serumula, Metse Regina."

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The effects of fumonisin B¹ in preeclampsia.
(2012) Serumula, Metse Regina.; Chuturgoon, Anil Amichund.; Moodley, Jagidesa.
Preeclampsia is the leading cause of foetal and maternal mortality and morbidity in developing countries. In South Africa, maize is a dietary staple for most black African populations and is susceptible to contamination by mycotoxins such as fumonisin B1 (FB1).Fumonisin B1 is a ubiquitous secondary metabolite of Fusarium fungi produced predominantly by Fusarium verticillioides. This mycotoxin shares structural similarities with the backbone of sphingoid bases (sphinganine and sphingosine) which are substrates for the biosynthesis of complex sphingolipids. The mechanism of FB1 toxicity therefore is centred on the disruption of this process. The aim of the present study was to elucidate the possible causal link between FB1 and preeclampsia. Following ethical approval, 20 normotensive and 20 preeclamptic patients were recruited into the study. Blood and placental tissue were collected and processed for further analysis. The presence of FB1 was verified using standard immunohistochemical and electrophoretic techniques. The levels of FB1 and sphingolipids were quantified using high performance liquid chromatography (HPLC). Western blotting was conducted to confirm the presence of FB1 in the serum. Placental tissue apoptosis was evaluated using Hoechst staining and other markers. Lipid peroxidation was measured in serum and placental tissue of both groups. Fumonisin B1 was immunolocalised within the endothelial cells and mesenchymal cells of placentas from both groups, while FB1 was present in cytotrophoblastic cells of preeclamptic patients only. In addition, FB1 concentrations were significantly higher in preeclamptic compared to normotensive serum samples. Sphinganine was significantly elevated in preeclamptic serum samples whilst there was no statistical difference in the sphingosine levels between the groups. Chromatin condensation was higher in the preeclamptic patients. Caspase 3 and Fas were present with greater intensity in preeclamptic samples. The levels of lipid peroxidation were significantly higher in both serum and placental tissue of preeclamptic patients. This study has demonstrated not only the presence of FB1 in the serum and placental tissues of pregnant women but also the potential effects of this mycotoxin in the humans.
The effects of Tulbaghia violacea (wild garlic) leaf and bulb extracts on an oesophageal cancer cell line (SNO)
(2012) Moonsamy, Suri.; Myburg, Rene Bernadette.; Serumula, Metse Regina.
Ethnopharmacological relevance: Indigenous plants such as Tulbaghia violacea(TV) and Allium sativum (garlic) are traditionally used as natural remedies to treat a variety of ailments, including cancer. This study investigated the effects of TV leaf and bulb extracts and garlic extract on a cancerous oesophageal cell line (SNO). Materials and methods: The methylthiazoltetrazolium (MTT) assay was used to determine the IC50 of TV leaf (TVL) (250μg/ml) and TV bulb extracts (TVB) (25μg/ml) and garlic (500μg/ml). Extracts were treated individually and in combination for a period of 24 hours. Oxidative damage and intracellular glutathione levels were assessed using the Thiobarbituric Acid Reactive Substances (TBARS) Assay and GSH-Glo™ Luminometry Assay, respectively. The CellTiter-Glo® Luminescent Cell Viability Assay was used to assess ATP activity. Induction of apoptosis and mitochondrial membrane potential were determined via the Caspase-Glo® 3/7 Assay, Caspase-Glo® 8 Assay, Caspase-Glo® 9 Assay and JC-1 Mitoscreen Assay, respectively. Morphological apoptotic changes were determined using the Hoechst 33342 stain. Expressions of p53, PARP and NFKB activities were determined by western blotting. Results: Bulb and leaf extracts of TV increased lipid peroxidation compared to the control (p>0.05), whilst garlic and combination of TV leaf and bulb (TVB + TVL) extracts significantly decreased lipid peroxidation relative to the control (p< 0.05). Endogenous glutathione levels significantly decreased in all TV treatments compared to the control (p<0.05).However, garlic was accompanied by insignificantly increased intracellular glutathione levels compared to the control (p> 0.05). The percentages of depolarised mitochondria in all treated cells were significantly decreased compared to untreated cells (p< 0.05). ATP levels increased significantly in garlic and combination (TVB + TVL) treated cells as compared to the control (p< 0.05), yet no significant differences were noted in TVL and TVB treatments (p> 0.05). Caspase8 and caspase 9 activities significantly increased in garlic and combination treated cells relative to the control (p<0.05). A similar trend was noted for caspase 3/7 activity in garlic and combination treatments (p< 0.05). However, initiator and executioner activities in TVL (p> 0.05) and TVB (p> 0.05) treatments did not significantly differ from the control (p> 0.05). All treatments (including garlic) resulted in increased DNA fragmentation and condensation. All treatments decreased p53 expression (p< 0.05), PARP expression (p< 0.05) and NFK B expression (p>0.05) compared to the control. Conclusions: All TV extracts and garlic induces apoptosis in the oesophageal cancerous SNO cell line through changes in oxidative stress, antioxidant systems, and nuclear chromatin condensation, as well as through induction of nuclear genes and signalling pathways. Since inhibition of apoptosis is a principal alteration in cancer, induction of apoptosis would result in a decrease in cancer cell growth. Thus, TV could be exploited as a potential anti-cancer agent.
The effects of Tulbaghia violacea leaf, bulb and stalk extracts on Jurkat cells.
(2012) Mackenzie, Jared Stuart.; Myburg, Rene Bernadette.; Serumula, Metse Regina.
Studies have shown that the traditional healers have used Tulbaghia violacea (TV) (also known as ‘wild garlic’) for the treatment of a number of ailments including fever, tuberculosis, stomach problems, and oesophageal cancer. However, little is known with regards to the anticancer and antiproliferative properties of this plant. Therefore, this study investigated the effects of TV and domesticated garlic extracts on Jurkat cells, in order to determine whether or not these extracts possess anti-proliferative properties. Cultured Jurkat cells were treated with IC50 concentrations of garlic (14μg/ml), TV leaf (256μg/ml), TV bulb (225μg/ml) and TV stalk (216μg/ml) extracts as determined by the methylthiazol tetrazolium assay. Free radical production was measured using the thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) assays, while glutathione (GSH) concentration was measured using the GSH-Glo™ assay. The apoptosis inducing properties of each extract were measured using flow cytometry (Annexin V- Fluos and JC-1 assays) and luminometry (caspases 3/7, 8, 9 and ATP). Western blots were run to determine protein expression, while comet and DNA fragmentation assays were used to determine the level of DNA damage induced. Wild and domesticated garlic extracts induced a significant increase in malondialdehyde concentration ([MDA]), with TV bulb extract inducing the highest concentration (p<0.0001). A significant increase in NO concentration was observed in the bulb (p<0.0001) and stalk (p<0.001) extracts, and leaf (p<0.05) and stalk (p<0.05) TV extracts significantly increasing GSH concentration. The longest comet tails were observed in TV bulb extracts (p<0.0001) and comprised mainly of single strand breaks, while the comets induced following garlic exposure contained double strand breaks. All extracts, except TV leaf, increased the percentage of cells undergoing apoptosis. Tulbaghia violacea leaf induced a significant (p<0.0001) increase in percentage of cells undergoing necrosis, whereas TV bulb resulted in a significant (p<0.0001) decrease. All TV extracts induced caspase 3/7 and 9 activity, with the most significant increase in caspase 9 activity observed for TV leaf and bulb. No significant change in caspase 3/7 activity was evident for domesticated garlic. Cleavage of PARP and expression of NF B and HSP 70 occured for all extracts. However, HSP 70 was not differentially expressed. Exposure to wild and domesticated garlic extracts induced peroxidative lipid and DNA damage within the cells, indicating oxidative stress. This damage occurred in conjunction with increased percentage of cells undergoing apoptosis and expression of caspase 3/7. Therefore, these findings suggest that TV is inducing cell death through apoptosis in Jurkat cells using a number of mechanisms, including the induction of oxidative stress. This is of clinical significance, as cell death through apoptosis is the preferred method of action for anti-cancer drugs.