UWCScholar :: Browsing by Author "Meyer, Mervin"

Browsing by Author "Meyer, Mervin"

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Analysis, expression profiling and characterization of hsa-miR-5698 target genes as putative dynamic network biomarkers for prostate cancer: a combined in silico and molecular approach
(University of the Western Cape, 2019) Lombe, Chipampe Patricia; Pretorius, Ashley; Meyer, Mervin
2018, the International Agency for Research on Cancer (IARC) estimated that prostate cancer (PCa) was the second leading cause of death in males worldwide. The number of deaths are expected to raise by 50 % in the next decade. This rise is attributed to the shortcomings of the current diagnostic, prognostic, and therapeutic biomarkers used in the management of the disease. Therefore, research into more sensitive, specific and effective biomarkers is a requirement. The use of biomarkers in PCa diagnosis and management takes advantage of the genetic alterations and abnormalities that characterise the disease. In this regard, a microRNA, hsa-miR-5698 was identified in a previous study as a differentiating biomarker between prostate adenocarcinoma and bone metastasis. Six putative translational targets (CDKN1A, CTNND1, FOXC1, LRP8, ELK1 and BIRC2) of this microRNA were discovered using in silico approaches. The aim of this study was to analyse via expression profiling and characterization, the target genes of hsa-miR-5698 in order to determine their ability to act as putative dynamic network biomarkers for PCa. The study was conducted using a combined in silico and molecular approach. The in silico part of the study investigated the putative transcriptional effects of hsa-miR-5698 on the promotors of its translational targets, the correlation between hsa-miR-5698 and mRNA expression profiles as well as the co-expression analysis, pathway analysis and prognostic ability of the target genes. A number of computational software were employed for these purposes, including, R Studio, Trident algorithm, STRING, KEGG, MEME Suite, SurvExpress and ProGgene. The molecular part of the study involved expression profiling of the genes in two PCa cell line LNCaP and PC3 via qPCR.
Antibacterial activity of rationally designed antimicrobial peptides
(Hindawi, 2020) Tincho, Marius B.; Morris, Thureyah; Meyer, Mervin
Many infectious diseases are still prevalent in the world’s populations since no effective treatments are available to eradicate them. e reasons may either be the antibiotic resistance towards the available therapeutic molecules or the slow rate of producing adequate therapeutic regimens to tackle the rapid growth of new infectious diseases, as well as the toxicity of current treatment regimens. Due to these reasons, there is a need to seek and develop novel therapeutic regimens to reduce the rapid scale of bacterial infections. Antimicrobial Peptides (AMPs) are components of the first line of defense for prokaryotes and eukaryotes and have a wide range of activities against Gram-negative and Gram-positive bacteria, fungi, cancer cells, and protozoa, as well as viruses. In this study, peptides which were initially identified for their HIV inhibitory activity were further screened for antibacterial activity through determination of their kinetics as well as their cytotoxicity. From the results obtained, the MICs of two AMPs (Molecule 3 and Molecule 7) were 12.5 μg/ml for K. pneumoniae (ATCC 700603) and 6.25 μg/ml for P. aeruginosa (ATCC 22108). e two AMPs killed these bacteria rapidly in vitro, preventing bacterial growth within few hours of treatment. Furthermore, the cytotoxic activity of these two peptides was significantly low, even at an AMP concentration of 100 μg/ml. ese results revealed that Molecule 3 and 7 have great potential as antibacterial drugs or could serve as lead compounds in the design of therapeutic regimens for the treatment of antibiotic-resistant bacteria.
Antibacterial activity of rationally designed antimicrobial peptides.
(Hindawi, 2020) Morris, Thureyah; Tincho, Marius Belmondo; Meyer, Mervin
Many infectious diseases are still prevalent in the world’s populations since no effective treatments are available to eradicate them. e reasons may either be the antibiotic resistance towards the available therapeutic molecules or the slow rate of producing adequate therapeutic regimens to tackle the rapid growth of new infectious diseases, as well as the toxicity of current treatment regimens. Due to these reasons, there is a need to seek and develop novel therapeutic regimens to reduce the rapid scale of bacterial infections. Antimicrobial Peptides (AMPs) are components of the first line of defense for prokaryotes and eukaryotes and have a wide range of activities against Gram-negative and Gram-positive bacteria, fungi, cancer cells, and protozoa, as well as viruses. In this study, peptides which were initially identified for their HIV inhibitory activity were further screened for antibacterial activity through determination of their kinetics as well as their cytotoxicity. From the results obtained, the MICs of two AMPs (Molecule 3 and Molecule 7) were 12.5 μg/ml for K. pneumoniae (ATCC 700603) and 6.25 μg/ml for P. aeruginosa (ATCC 22108). e two AMPs killed these bacteria rapidly in vitro, preventing bacterial growth within few hours of treatment. Furthermore, the cytotoxic activity of these two peptides was significantly low, even at an AMP concentration of 100 μg/ml. ese results revealed that Molecule 3 and 7 have great potential as antibacterial drugs or could serve as lead compounds in the design of therapeutic regimens for the treatment of antibiotic-resistant bacteria.
Antioxidant and antimicrobial activities of green-synthesized silver nanoparticles using a cocktaila aqueous extract of capparis sepiaria root and tabernaemontana elegans bark
(Wiley, 2025) Mashilo, Cate M.; Sibuyi Nicole RS; Botha, Subelia; Meyer, Mervin; Madiehe, Abram M
The increasing incidence of antimicrobial resistance (AMR) poses a serious threat to public health, which necessitates the development of alternative countermeasures to combat it. Green nanotechnology, in particular the use of silver nanoparticles (AgNPs), shows promise in combating AMR. Although the synthesis of AgNPs using medicinal plant extracts has been explored, combining extracts from two medicinal plants to synthesize AgNPs with enhanced properties has received less attention. Therefore, this study addresses this gap by presenting the green synthesis of AgNPs using a cocktail of Capparis sepiaria–Tabernaemontana elegans (CsTe) aqueous extract as reducing, stabilizing, and capping agents. The focus is on assessing the antioxidant and antimicrobial activities of the synthesized CsTe-AgNPs. Various parameters, such as pH, temperature, extract and silver concentrations, reaction ratio, and synthesis time, were optimized to enhance the efficiency of CsTe-AgNPs synthesis. The CsTe- AgNPs were monodispersed and spherical, with an average core size of 14 ± 2.953 and 7 ± 3.849 nm, and hydrodynamic size of 23 ± 12.260 and 138 ± 2.086 nm for pH = 6 and pH = 11, respectively. The FTIR analysis revealed a shift in peaks of biomolecules present in the CsTe extracts that could be responsible for the reduction of Ag salt to form CsTe-AgNPs. Notably, CsTe-AgNPs_pH11 had potent antimicrobial activity, with a minimum inhibitory concentration (MIC) of 12.5 ± 0 μg/mL against K. pneumoniae and P. aeruginosa, and a slightly higher MIC for C. albicans of 25 ± 5.449 μg/mL. This study demonstrated the effectiveness of using a mixture of two extracts to synthesize AgNPs with enhanced antioxidant and antimicrobial activities, and therefore, could serve as a promising reagent to combat AMR.
The antioxidant and in vitro wound healing activity of cotyledon orbiculata aqueous extract and the synthesized biogenic silver nanoparticles
(MDPI, 2022) Tyavambiza, Caroline; Meyer, Mervin; Madiehe, Abram Madimabe
The synthesis of silver nanoparticles using biogenic methods, particularly plants, has led to the discovery of several effective nanoparticles. In many instances, plant-derived silver nanoparticles have been shown to have more activity than the plant extract which was used to synthesize the nanoparticles. Silver nanoparticles have been successfully synthesized using the medicinal plant, Cotyledon orbiculata. This is a shrub found in the Western Cape province of South Africa. It has a long history of use in traditional medicine in the treatment of wounds and skin infections. The C. orbiculata synthesized silver nanoparticles (Cotyledon-AgNPs) were reported to have good antimicrobial and anti-inflammatory activities; however, their wound-healing properties have not been determined. This study aimed to determine the wound healing activity of Cotyledon-AgNPs using the scratch assay. Gene expression studies were also done to determine the nanoparticles’ mechanism of action. The Cotyledon-AgNPs showed good antioxidant, growth-promoting and cell migration properties.
Aptamer selection against GFRa1 for its application in the prognosis of breast cancer
(University of the Western Cape, 2019) Swartz, Lauren Taryn; Meyer, Mervin
Breast cancer is the second most common cancer amongst South African women. Despite ongoing efforts to combat breast cancer, current prognostic and/or therapeutic monitoring methods are limited since very little improvement, in the rate of long term recurrence of breast cancer, has been observed. Considering this, developing novel strategies to detect breast cancer recurrence – at an early onset – is crucial for monitoring the disease and potentially preventing disease progression. Methods currently used for the detection of BC are costly and can also be very uncomfortable for the patient. These methods are also too costly to use as a routine test, following surgery or treatment to assess disease progression. Thus, developing a cost-effective detection method appears to be an appealing alternative. Serum/blood-based biomarkers are ideal targets for the development of low cost detection assays. Two candidate biomarkers, unique ligand binding protein 2 (ULBP2) and glial cell line-derived neurotrophic factor family receptor alpha 1 (GFR1) were identified using bioinformatics and proteomics, respectively. These biomarkers have demonstrated to be useful prognostic biomarkers for breast cancer. The selection of aptamers against these biomarkers can facilitate the development of cost-effective detection methods. Aptamers are short DNA or RNA oligonucleotides that have very high affinity and specificity for its targets and can potentially replace antibodies as tools for molecular recognition in detection systems, such as the enzyme-linked immunosorbent assay (ELISA), lateral flow assays and electrochemical biosensors.
Biochemical investigation of anti-cancer activity of Tulbaghia violacea
(UWC, 2012) Saibu, Gbemisola Morounke; Meyer, Mervin; Katerere, David
Natural products have been a source of many pharmaceutical drugs and a number of drugs that are currently used in the treatment of cancer are derivatives of compounds originally isolated from natural products. There is evidence that extracts of Tulbaghia violacea can be used to treat cancer. The activation of apoptosis in cancer cells is a target for the development of novel anti-cancer drugs since one of the characteristics of cancer cells is resistance to apoptosis due to the deregulation of biochemical pathways leading to apoptosis. In fact, many current anti-cancer drugs exert their effects through the activation of apoptosis. Previous studies showed that extracts of T.violacea induce apoptosis in cancer cells and one study reported on the isolation of a compound (methyl-ԃ-D-glucopyranoside), which is responsible for the pro-apoptotic activity of the T.violacea extract. Therefore the aim of this study was to investigate the anti-cancer activity of methyl-ԃ-Dglucopyranoside and extracts prepared from T.violacea. In this study the pro-apoptotic activity of methyl-ԃ-D-glucopyranoside and extracts prepared from T.violacea were investigated on a panel of human cancer cell lines, which included HepG2, MCF7, H157, HT29 and the non-cancerous cell line, KMST6. The induction of apoptosis was evaluated by flow cytometry using several bioassays which measures biochemical events (caspase activation, phosphatidylserine externalisation and reactive oxygen species (ROS) production that is associated with the induction of apoptosis. The results demonstrated that the effects of methyl--D-glucopyranoside on cultured cells are transient and that the cells recover from the effects of methyl--D-glucopyranoside. This suggested thatmethyl-ԃ-D-glucopyranoside is not the compound responsible for the pro-apoptotic bioactivity in the T.violacea extract. This study also showed that cytotoxic and pro-apoptotic bioactivity of the leaf-extract was significantly higher in comparison to the tuber-extract. The bioactivity of the organic solvent extracts (dichloromethane, hexane, methanol and 50% methanol/water) of T.violacea leaves was also significantly higher than water extracts of T.violacea leaves. A comparison of the different organic extracts prepared from the T.violacea leaves showed that the highest activity was observed for the dichloromethane and hexane extracts. In an effort to identify the bioactive compound(s) the dichloromethane extract was subjected to Versaflash® column chromatography. However, due to problems experienced with the solubility of the dichloromethane sub-fractions, these compounds could not be tested for their bioactivity. Palmitone (16-hentriacontanone) was identified as one of the major compounds present in the dichloromethane sub-fractions. This compound was previously shown to have anticonvulsant bioactivity but there is no evidence in the literature that it has anti-cancer or pro-apoptotic activities. Fingerprinting of the methanol extract showed the presence of long chain fatty acid derivatives, flavonoids and allicin derivatives in the methanol extract. Although, this study failed to isolate the pro-apoptotic bioactive compound(s) present in the extracts of T.violacea, it confirmed that extracts of this plant induce apoptosis in cultured human cancer cell lines.
Biogenic synthesis of gold nanoparticles using red and green pear fruit extracts
(University of the Western Cape, 2019) Barry, Simone Caroline Leslie; Meyer, Mervin
There has been a growing interest in the design of biocompatible and environmentally affable nanoparticles (NPs) among scientists to develop novel and safe biomaterials for use in various biomedical applications. This can be obtained through the use of plant and/ or fruit-derived phytochemicals that are capable of reducing gold ions into gold nanoparticles (AuNPs). Several studies have shown that different plant and fruit extracts possess different pharmacological properties as a result of their phytochemical profile and are capable of synthesising AuNPs with potential applications in medicine. Pears possess a unique phytochemical profile and these phytochemicals vary in the different parts of the pear and allows pears to exhibit beneficial pharmacological activities such as antioxidant, antimicrobial, anticarcinogenic as well as anti-inflammatory properties. Anthocyanins are important pigments responsible for the colouration of fruits but also have multiple uses in traditional Chinese medicine. Anthocyanins are strong antioxidants and since these molecules are present in pears, they could possibly be able to reduce gold (III) chloride to form NPs. The red-coloured ‘Bon Rouge’ pear contains higher levels of anthocyanins in comparison to the green-coloured ‘Williams Bon Chretien’ pear of which it is a mutant bud. A comprehensive study of the capability of the ‘Williams Bon Chretien’ and ‘Bon Rouge’ pears as the novel materials for the biogenic synthesis of AuNPs was conducted. Differences in the physicochemical properties of these AuNPs and potential biological applications based on the influence of anthocyanins and other phytochemicals within the pears were also explored. In addition, the effect of reaction temperature and extract concentration as well as kinetics as a function of time on the synthesis of AuNPs were conducted. The synthesized AuNPs were characterised for their size, polydispersity, morphology, crystallinity, active functional groups and in vitro stability.
Chemical and biological evaluation of palythoa tuberculosa collected from the red sea
(University of the Western Cape, 2015) Elbagory, Abdulrahman Mohammed; Mohammed, Ahmed; Meyer, Mervin
A chemical study on the total extract of the zoanthid Palythoa tuberculosa, collected from the Red Sea, resulted in the isolation of seven polyhydroxylated sterols viz: palysterols A-G, six of which are new. Their chemical structures were elucidated on the basis of their 1D and 2D NMR and MS spectroscopic data. Palysterols B and G demonstrated cytotoxic activity on three human cancer cell lines (MCF-7, HeLa, and HT- 29). Palysterol G, in particular, was able to induce apoptosis in breast adenocarcinoma(MCF-7) cells
Development of a receptor targeted nanotherapy using a proapoptotic peptide
(University of the Western Cape, 2015) Sibuyi, Nicole Remaliah Samantha; Meyer, Mervin; Madiehe, Abram M.
The prevalence of obesity amongst South Africans is alarming, with more than 29% of men and 56% of women considered to be obese. Angiogenesis, a process for development of new blood vessels play a major role in growth and survival of the adipose tissues. Pharmacological inhibitors of angiogenesis are therefore a sensible strategy to reduce excess body weight. Current anti-obesity drugs have limitations because of their lack of selectivity and specificity, which lead to undesirable side effects and reduced drug efficacy. Future anti-obesity therapeutic strategies should be target-specific, with minimal toxicity towards healthy tissues will be more appropriate for obesity treatment. Targeted nano-therapeutic agents are currently being developed to overcome the drawbacks associated with conventional drug therapies. The nano-based delivery vehicles that specifically target diseased cells are appealing as they could reduce drug toxicity towards healthy tissues and be more effective at lower dosages. The main aim of this study was to develop a receptor-mediated nanotherapy that specifically targets the white adipose tissue vasculature and trigger the death of these cells through apoptosis. The 14 nm gold nanoparticles (AuNPs) were synthesized using theTurkevich method following reduction of gold aurate by sodium citrate salt. Different chemistries were used to functionalise the AuNPs for biological application by conjugating with either vascular targeting peptide or pro-apoptotic peptide on their surface or both. The nanomaterials were characterised by UV-Vis, Zeta potential and transmission electron microscopy (TEM). The sensitivity and specificity of various AuNP conjugates were tested in vitro on colon and breast cancer cell lines. A human (Caco-2) cell line that expresses the receptor for the adipose homing peptide was chosen as an in vitro model system. Cellular toxicity and uptake of the nanoparticles was evaluated using the WST-1 assay, Inductively Coupled Plasma-Optical Emission Spectra (ICP-OES) and TEM. The induction of apoptosis following exposure to the nanoparticles was examined by Western blot and flow cytometric analysis. The anti-proliferative activity of the targeted therapeutic nanoparticles on the cells was more pronounced on the cells expressing the receptor for the adipose homing peptide. The uptake of unfunctionalised AuNPs was higher compared to functionalised nanoparticles, but this did not impair cell viability. The activity of the therapeutic peptide was retained and enhanced following conjugation to AuNPs as shown by Western blot and flow cytometric analysis. The nanotherapy under study demonstrated receptor mediated targeting, and enhanced activity on the cells expressing the receptor. However, the therapeutic and efficacy of the targeted nanotherapy still need to be tested in animal models of obesity to confirm the treatment specificity.
Development of an aptamer based lateral flow test strip for a diabetes biomarker
(University of the Western Cape, 2019) Moabelo, Koena Leah; Meyer, Mervin
Diabetes mellitus is one of the major chronic diseases that poses a significant risk to human health globally. Current diagnostics for diabetes are based on blood glucose measurements, which can go unnoticed for years. As such, there is an urgent need for diagnosis of diabetes at the point-of-care (PoC), and in low-income settings. Recent developments in the field of nanotechnology, and the use of aptamers show great promise in developing sensitive and disease-specific assays. Aptamers have high specificity, selectivity, low molecular weight, nontoxicity, non-immunogenicity, and are easy to produce. The aim of the study was to characterize and identify dual aptamers for the development of an aptamer-based PoC diagnostic kit for diabetes. Retinol binding protein 4 (RBP4) and its binding aptamers were identified through in silico approach. The secondary structures of the selected retinol binding aptamers (RBA) were predicted by M-fold and Quadruplex forming G-Rich Sequences mapper. Binding affinity of aptamers to the biomarker was characterized by Surface Plasmon Resonance(SPR), Electrophoretic mobility shift assay (EMSA) and Enzyme-Linked Aptamer Assay (ELAA) and the aptamer pairs were evaluated by sandwich-based SPR and ELAA. Gold nanoparticles (AuNPs) were synthesized using the Turkevich method, and characterized by UV-visible (UV-vis) spectrophotometry, Zetasizer and Transmission Electron Microscopy. One aptamer was conjugated to AuNPs and the conjugate was characterized by UV-Vis, Zetasizer, Qubit assay and gel electrophoresis. The apt-AuNPs were used in the preparation of the lateral flow test strips and a colorimetric aptasensor for the detection of RBP4.
The development of nanotechnology-based detection systems for the diagnosis of breast cancer
(University of the Western Cape, 2015) Drah, Mustafa; Meyer, Mervin
Breast cancer is one of the major causes of death in South Africa. About 1 in 29 South African women are at risk of developing this type of cancer in their lifetime. The global incidence of breast cancer also increases annually with over 1 million new cases diagnosed every year. Molecular diagnostic techniques such as qRT-PCR, Fluorescent In Situ Hybridization (FISH), Immunohistochemistry (IHC) and ELISA are used to diagnose breast cancer. Some of these diagnostic techniques make use organic fluorophores as fluorescent reporter molecules. The principle of all these diagnostic techniques is reliant on the detection of molecular biomarkers that are associated with the disease. In most cases these molecular biomarkers are DNA, RNA or proteins that are up-regulated in response to or as a result of the disease. The first aim of this study was therefore to identify membrane proteins that are up-regulated in cancers that can potentially be used as biomarkers for the detection of breast cancer. The second aim of this study was to investigate the application of quantum dots in the development of a molecular diagnostic test that can detect a breast cancer biomarker. The most commonly used method to identify molecular biomarkers for diseases have traditionally been gene expression analysis using technologies such as DNA microarray. These technologies have certain limitations and have therefore not been very successful in identifying useful disease biomarkers. Biomarker II discovery by proteomics can overcome some of these limitations and is potentially a more suitable method to identify molecular biomarkers for breast cancer. In this study proteomics in combination with Stable Isotope Labelling with Amino Acids in Cell Culture SILAC was used to do a comparative analysis of the expression levels of membrane proteins present in a human breast cancer cell line (MCF-7) derived from a breast cancer patient and a human breast cell line (MCF- 12A) derived from a healthy individual. This led to the identification of the transmembrane protein, GFRA1 as potential new biomarker for breast cancer. This study showed that this protein is over expressed in MCF-7 cells as compared to MCF-12A cells and that it is also highly expressed in the myoepthelial cells of the milk ducts of breast cancer patients. This study also demonstrates the use of molecular beacon technology to develop a DNA probe for the detection of cDNA encoding the CK19 gene, which is a known biomarker for breast cancer. In the development of this probe, quantum dots were used as the fluorescence reporter. This molecular beacon probe was able to demonstrate the over expression of CK19 in MCF-7 cells. This study shows that this technology can potentially be used as a diagnostic test for breast cancer and since quantum dots are used in the development of these molecular beacon probes, this diagnostic test can potentially facilitate the development of multiplex detection systems for the diagnosis of breast cancer. Molecular beacon technology can potentially also be used to detect novel biomarkers such as GFRA1.
Development of nanotechnology-based therapeutic approaches to treat HIV
(University of the Western Cape, 2012) Dodgen, Cleo; Meyer, Mervin
The rapidly expanding field of nanotechnology has been the focus of many biologists with regard to drug delivery. The ability of nanoparticles to enter cellular compartments makes it possible to explore specific treatment strategies for life-threatening diseases such as AIDS. Since HIV primarily infects CD4+ cells, we aim to use CD4 as a selectable marker to deliver pro-apoptotic nano-devices to HIV infected cells. The objective is to selectively induce cell death or apoptosis in CD4+ HIV infected cells. Apoptosis is activated through a number of biochemical pathways. The apoptosis promoting protease, caspase-3 is central to the induction of apoptosis. Caspase-3 is produced as an inactive zymogen and is activated by other proteases through proteolytic cleavage. We take advantage of the fact that HIV-infected cells produce HIV-1 protease, which is responsible for the production of infectious virions through proteolytic cleavage of the HIV proteins, Gag and Pol. Our strategy was to generate a mutant form of the caspase-3 protease that is only cleavable by HIV-1 protease.
Discriminative eradication of cancer cells using quantum dots functionalised with peptide-directed delivery of a pro-apoptotic peptide
(2013) Swartz, Lauren Taryn; Meyer, Mervin; Onani, Martin
The therapeutic goal of cancer treatment is to trigger selective cell death in cancer cells. To eliminate cancerous cells effectively, the anti–cancer drugs must be targeted to the affected cells. However, anti–cancer drugs are often distributed non–specifically giving rise to systemic toxicities and other adverse effects. Cancer specific peptides are useful cancer targeting agents that can be used for the targeted delivery of anti-cancer drugs. Several cancer targeting peptides and some of their corresponding protein targets have been identified. Previous work investigated the specific binding of five of these peptides (p.C, p.H, p6.1, Frop-1 and p.L) conjugated to fluorescent nanoparticles (quantum dots) to a panel of human cell lines, which included four cancerous cell lines (Caco-2, HeLa, HT29 and HepG2) and one non-cancerous cell line (KMST-6). Flow cytometry showed that the p.L peptide preferentially bind to HT29 cells; suggesting that the expression levels of the target for the p.L peptide are higher in these cells. The objective of this study was to make use of target specific functionalised quantum dots (QDs) to deliver Second mitochondria-derived activator of caspases/ Direct AIP binding protein with low PI (Smac/DIABLO) to HT29 cells with the aim of enhancing the effects of pro-apoptotic drugs. Smac/DIABLO is a pro-apoptotic peptide that is able to interact with inhibitor of apoptosis proteins (IAPs), thereby inducing pro-apoptotic signalling. Methodology: CdSe/ZnS core-shell QDs were synthesised using the one-pot synthesis method. These QDs were characterised using photoluminescence (PL) spectroscopy, high resolution transmission electron microscopy (HR-TEM) and energy dispersive x-ray spectroscopy (EDS). The CdSe/ZnS core-shell QDs were solubilised with L-cysteine (Cys- QDs). The Cys-QDs were bi-conjugated to the p.L peptide and Smac peptide using 1-ethyl-3- (30-dimethylamino) carbodiimide (EDC) chemistry. Cultured HT29 cells were exposed to the 10 | P a g e QD peptide bi-conjugates and fluorescence microscopy was employed to assess targeting and internalisation. The cytotoxicity of the QD peptide bi-conjugates in combinatorial treatment with ceramide was evaluated using the WST-1 Cell Proliferation assay. A commercially available QD with similar chemistry was used to carry out a comparative study to relate the efficiency of the in-house synthesized QD.
Evaluation of cytotoxic activity of gold nanoparticles naturally synthesised from South African indigenous medicinal plant extracts
(University of the Western Cape, 2018) Mbandezi, Yamkela; Meyer, Mervin; Mohammed, Ahmed
Nanotechnology has emerged as a promising field in the quest to address health conditions. Green nanotechnology is a fairly new branch of nanotechnology, which aims to produce and utilize nanomaterials in a way that is safe for living organisms and their environment. Plant extracts are increasingly used in the green synthesis of gold nanoparticles (AuNPs), which involves the reduction of sodium tetrachloroaurate (III) dehydrate by phytochemicals present in the plant extract. It is probable that the green synthesised AuNPs are more biocompatible than chemically synthesised AuNPs as biomolecules of plant origin are involved in the synthesis process. Therefore, this study aimed to explore various water extracts from indigenous South African plants, which included Perlagonium capitatum, Otholobium bracteolatum, Gerbera linnae, Morrella quercifolia, Searsia lucida, Phylica bubescens, Euclea racemosa, Tetragonia fruticosa, and Searsia glauca for their potential to synthesize AuNPs and to investigate their toxicity towards several microorganisms known to cause skin infections. These organisms play a significant role in delaying the healing of wounds. The antimicrobial properties of nanoparticles are increasing exploited in the production of wound treatments.
Flavonoid and phenolic acid profiles of dehulled and whole vigna subterranea (l.) Verdc seeds commonly consumed in South Africa
(MDPI, 2022) Okafor, Jane N. C.; Meyer, Mervin; Roes-Hill, Marilize Le
Bambara groundnut (BGN) is an underexploited crop with a rich nutrient content and is used in traditional medicine, but limited information is available on the quantitative characterization of its flavonoids and phenolic acids. We investigated the phenolic profile of whole seeds and cotyledons of five BGN varieties consumed in South Africa using UPLC-qTOF-MS and GC-MS. Twenty-six phenolic compounds were detected/quantified in whole seeds and twenty-four in cotyledon, with six unidentified compounds.
Gold nanoparticles synthesized using extracts of cyclopia intermedia, commonly known as honeybush, amplify the cytotoxic effects of doxorubicin
(MPDI, 2021) Sibuyi, Nicole Remaliah Samantha; Aboyewa, Jumoke A.; Meyer, Mervin
Cyclopia intermedia (C. intermedia) is an indigenous South African shrub used to prepare the popular medicinal honeybush (HB) tea. This plant contains high levels of mangiferin (MGF), a xanthonoid that was reported to have numerous biological activities, including anti-tumor activity. MGF and extracts that contain high concentrations of MGF, such as extracts from Mangifera indica L. or mango have been used to synthesize gold nanoparticles (AuNPs) using green nanotechnology. It has previously been shown that when AuNPs synthesized from M. indica L. extracts are used in combination with doxorubicin (DOX) and Ayurvedic medicine, the anti-tumor effects appear to be augmented. It has also been demonstrated that MGF used in combination with DOX resulted in enhanced anti-tumor effects. In this study, C. intermedia (HB) and MGF were used to synthesize HB-AuNPs and MGF-AuNPs, respectively. The physicochemical properties of the AuNPs were characterized by the UV-Visible Spectroscopy (UV-Vis), dynamic light scattering (DLS), Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HR-TEM). The cytotoxicity of HB-AuNPs and MGF-AuNPs were assessed on human colon (Caco-2), prostate (PC-3) and glioblastoma (U87) cancer cells; as well as normal breast epithelial (MCF-12A) cells using the MTT assay. Both HB-AuNPs and MGF-AuNPs demonstrated relatively low cytotoxicity in these cells. However, when these nanoparticles were used in combination with DOX, the cytotoxicity of DOX was significantly augmented.
Green synthesis and characterization of gold nanoparticles from South African plants and their biological evaluations
(University of the Western Cape, 2019) Elbagory, Abdulrahman Mohammed Mohammed Nagy; Meyer, Mervin; Hussein, Ahmed
The field of nanotechnology continues to offer solutions for biotechnologists whose target is to improve the quality of life by finding new therapies to combat diseases. Gold nanoparticles (AuNPs) have been showing great potentials in many biomedical applications. The antibacterial activity of the AuNPs presents a therapeutic option for conditions caused by bacterial infections such as chronic wounds. Also, these versatile particles can offer solutions in the treatments of infectious diseases and can also be exploited as “smart” vehicles to carry drugs, such as antibiotics, for improved efficiency. Moreover, the anti-inflammatory activity of AuNPs makes them useful in the management of prolonged inflammation caused by bacterial infections. The synthesis of AuNPs can be achieved by variety of physical and chemical methods that have been successfully applied in labs and industry. Nonetheless, the drawbacks of these “conventional” methods in terms of high cost, adverse health side effects and incompatibility with the ecosystem cannot be overlooked. Thus, new safer and more cost-effective protocols have been reported for the synthesis of AuNPs. Plants have provided alternate synthesis methods in which the reducing capabilities of the phytochemicals, found in the aqueous plant extracts, can be used to chemically synthesize AuNPs from gold precursors. The biosynthesis and characterization of AuNPs from the phytochemicals of several South African plants is investigated in this study. The study also reports the optimization of the AuNPs biosynthesis by varying reaction conditions such as temperature and plant extracts’ concentrations. Furthermore, the study highlights the wound healing activity of the AuNPs synthesized from selected plants by investigating their antibacterial activity on bacterial strains known to cause chronic wounds. The ability of these AuNPs to carry ampicillin in order to enhance the antibacterial activity is also described herein. The cytotoxicity of the biosynthesized AuNPs was evaluated on human normal fibroblasts cells (KMST-6). Additionally, the immunomodulatory effect of the biosynthesized AuNPs on the cytokines production from macrophages and Natural Killer (NK) cells was examined. The study was successful to produce biocompatible and safe AuNPs synthesized from the tested aqueous plant extracts. The resulted AuNPs showed different physicochemical properties by varying the reaction conditions. The AuNPs exhibited antibacterial activity against several Gram-positive and Gram-negative bacteria. Also, ampicillin was successfully loaded on the biosynthesized AuNPs, which led to the formation of more antibacterial active conjugated AuNPs compared to the free AuNPs. The green synthesized AuNPs were also found to have anti-inflammatory responses as shown by the reduction of pro-inflammatory cytokines from immune cells. In vitro assays showed that the biogenic AuNPs were not toxic to KMST-6 cells. Overall, the data suggest that plant extracts produce biologically safe AuNPs with antibacterial and anti-inflammatory activities that can be exploited in the treatment of chronic wounds and in the management of chronic inflammation.
Green synthesis and characterization of silver nanoparticles (AgNPs) from Bulbine frutescens leaf extract and their antimicrobial effects
(University of the Western Cape, 2020) Lucas, Shakeela; Madiehe, Abram; Meyer, Mervin
Combating antimicrobial resistant infections caused by nosocomial pathogens poses a major public health problem globally. The widespread use of broad-spectrum antibiotics for the treatment of wound infections has led to the appearance of multidrug-resistant (MDR) microbes which further exacerbates the growth of microbes amongst patients. It may result in prolonged debility of the patient and an increase in healthcare costs due to prolonged hospital stays and expensive treatment regimens to avoid patient-patient transmission. Therefore, it is imperative that alternative sources of treatment to antimicrobial use in wound infections needs to be developed in order to inhibit or kill resistant microbes and to provide point of care medical treatment to the less fortunate at an affordable cost.
Green synthesis of metallic nanoparticles using some selected medicinal plants from Southern Africa and their biological applications
(MPDI, 2021) Aboyewa, Jumoke A.; Sibuyi, Nicole R. S.; Meyer, Mervin
The application of metallic nanoparticles (MNPs), especially that of silver, gold, cobalt, and zinc as antimicrobial, anticancer, drug delivery, contrast, and bioimaging agents has transformed the field of medicine. Their functions, which are attributed to their physicochemical properties, have gained prominence in various technological fields. Although MNPs can be produced via rigorous physical and chemical techniques, in recent years, a biological approach utilizing natural materials has been developed. With the increasing enthusiasm for safe and efficient nanomaterials, the biological method incorporating microorganisms and plants is preferred over physical and chemical methods of nanoparticle synthesis. Of these bio-entities, plants have received great attention owing to their capability to reduce and stabilize MNPs in a single one-pot protocol. South Africa is home to ~10% of the world’s plant species, making it a major contributor to the world’s ecological scenery. Despite the documented contribution of South African plants, particularly in herbal medicine, very few of these plants have been explored for the synthesis of the noble MNPs.

Browsing by Author "Meyer, Mervin"

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