Photophysico-chemical properties and photoinactivation of Staphylococcus Aureus using zinc phthalocyanines linked silver nanoparticles conjugates
- Matlou, Gauta G, Nyokong, Tebello
- Authors: Matlou, Gauta G , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186278 , vital:44481 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108237"
- Description: The synthesis of zinc (II) tri (tert-butyl phenoxy) mono cinnamic acid Pc (complex 1) is reported for the first time in this work. Complex 1 and the reported zinc (II) tri (tert-butyl), mono cinnamic acid phthalocyanine (2), zinc (II) mono cinnamic acid substituted phthalocyanine (3) and zinc (II) tetra cinnamic acid substituted phthalocyanine (4) are conjugated to cysteine capped silver nanoparticles (cys-AgNPs) through an amide bond. The photophysicochemical properties and the photodynamic antimicrobial chemotherapy (PACT) activities of the Pc-cys-AgNPs conjugates and the Pcs alone on S. Aureus are reported. Improved triplet and singlet oxygen quantum yields were observed for the conjugated complexes compared to Pcs alone, due to the heavy atom effect of cys-AgNPs. Asymmetric complexes 1,2, 3 and their respective conjugates recorded higher photosensitizing properties and PACT activities compared to 4 and 4-cys-AgNPs, respectively. Higher log reductions and percentage reductions of S. Aureus were recorded for conjugated complexes compared to ZnPcs only, showing enhanced PACT activities due to their higher singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2020
- Authors: Matlou, Gauta G , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186278 , vital:44481 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108237"
- Description: The synthesis of zinc (II) tri (tert-butyl phenoxy) mono cinnamic acid Pc (complex 1) is reported for the first time in this work. Complex 1 and the reported zinc (II) tri (tert-butyl), mono cinnamic acid phthalocyanine (2), zinc (II) mono cinnamic acid substituted phthalocyanine (3) and zinc (II) tetra cinnamic acid substituted phthalocyanine (4) are conjugated to cysteine capped silver nanoparticles (cys-AgNPs) through an amide bond. The photophysicochemical properties and the photodynamic antimicrobial chemotherapy (PACT) activities of the Pc-cys-AgNPs conjugates and the Pcs alone on S. Aureus are reported. Improved triplet and singlet oxygen quantum yields were observed for the conjugated complexes compared to Pcs alone, due to the heavy atom effect of cys-AgNPs. Asymmetric complexes 1,2, 3 and their respective conjugates recorded higher photosensitizing properties and PACT activities compared to 4 and 4-cys-AgNPs, respectively. Higher log reductions and percentage reductions of S. Aureus were recorded for conjugated complexes compared to ZnPcs only, showing enhanced PACT activities due to their higher singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2020
Plant-Based Synthesis of Silver Nanoparticles Using Aqueous Leaf Extract of Salvia officinalis: Characterization and its Antiplasmodial Activity
- Okaiyeto, Kunle, Hoppe, Heinrich, Okoh, Anthony I
- Authors: Okaiyeto, Kunle , Hoppe, Heinrich , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429472 , vital:72613 , xlink:href="https://doi.org/10.1007/s10876-020-01766-y"
- Description: In the present study, an aqueous leaf extract of Salvia officinalis was used to synthesize silver nanoparticles (AgNPs) and characterized with different techniques such as UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Subsequently, its cytotoxic effect against human cervix adenocarcinoma (HeLa) cells and antiplasmodial activity against Plasmodium falciparum were investigated. UV–vis spectrum of AgNPs displayed an absorption peak at 323 nm and TEM result revealed it to be spherical in shape with average size of 41 nm. FTIR results highlighted the key bioactive compounds that could be responsible for the reduction and capping of AgNPs and XRD analysis showed its crystalline nature with a face-centered cubic (fcc) structure. The synthesized AgNPs was found to be less cytotoxic against HeLa cells line and demonstrated good antiplasmodial potential (IC50 = 3.6 µg/mL). Findings from this study indicated that the AgNPs could serve as a template in the development of new drugs for the control of malaria and hence, further study is needed to identify and characterize the potent molecules that suppress the malaria parasite.
- Full Text:
- Date Issued: 2020
- Authors: Okaiyeto, Kunle , Hoppe, Heinrich , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429472 , vital:72613 , xlink:href="https://doi.org/10.1007/s10876-020-01766-y"
- Description: In the present study, an aqueous leaf extract of Salvia officinalis was used to synthesize silver nanoparticles (AgNPs) and characterized with different techniques such as UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Subsequently, its cytotoxic effect against human cervix adenocarcinoma (HeLa) cells and antiplasmodial activity against Plasmodium falciparum were investigated. UV–vis spectrum of AgNPs displayed an absorption peak at 323 nm and TEM result revealed it to be spherical in shape with average size of 41 nm. FTIR results highlighted the key bioactive compounds that could be responsible for the reduction and capping of AgNPs and XRD analysis showed its crystalline nature with a face-centered cubic (fcc) structure. The synthesized AgNPs was found to be less cytotoxic against HeLa cells line and demonstrated good antiplasmodial potential (IC50 = 3.6 µg/mL). Findings from this study indicated that the AgNPs could serve as a template in the development of new drugs for the control of malaria and hence, further study is needed to identify and characterize the potent molecules that suppress the malaria parasite.
- Full Text:
- Date Issued: 2020
Preformulation studies of efavirenz with lipid excipients using thermal and spectroscopic techniques
- Makoni, Pedzisai A, Kasongo, Kasongo W, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Kasongo, Kasongo W , Walker, Roderick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183253 , vital:43934 , xlink:href=" https://doi.org/10.1691/ph.2020.0053"
- Description: Investigation and identification of potential lipids for the manufacture of efavirenz loaded solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) was undertaken. Polymorphic modification and characteristics of the lipids with the best solubilising potential for efavirenz was explored using Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Wide-angle X-ray Scattering (WAXS). Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate (GM) and Transcutol® HP (THP) exhibiting the best solubilising potential for EFV. GM exists in a stable β-polymorphic modification prior to exposure to heat, but exists in an α-polymorphic modification following exposure to heat. However, it was established that the addition of THP to GM revealed the co-existence of the α- and β'-polymorphic modifications of the lipid. EFV (60% w/w) exists in a crystalline state in a 70:30 mixture of GM and THP. Investigation of binary mixtures of EFV/GM and GM/THP, in addition to eutectic mixtures of EFV, GM and THP using FT-IR, DSC and WAXS revealed no potential interactions between EFV and the lipids selected for the production of the nanocarriers.
- Full Text:
- Date Issued: 2020
Preformulation studies of efavirenz with lipid excipients using thermal and spectroscopic techniques
- Authors: Makoni, Pedzisai A , Kasongo, Kasongo W , Walker, Roderick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183253 , vital:43934 , xlink:href=" https://doi.org/10.1691/ph.2020.0053"
- Description: Investigation and identification of potential lipids for the manufacture of efavirenz loaded solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) was undertaken. Polymorphic modification and characteristics of the lipids with the best solubilising potential for efavirenz was explored using Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Wide-angle X-ray Scattering (WAXS). Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate (GM) and Transcutol® HP (THP) exhibiting the best solubilising potential for EFV. GM exists in a stable β-polymorphic modification prior to exposure to heat, but exists in an α-polymorphic modification following exposure to heat. However, it was established that the addition of THP to GM revealed the co-existence of the α- and β'-polymorphic modifications of the lipid. EFV (60% w/w) exists in a crystalline state in a 70:30 mixture of GM and THP. Investigation of binary mixtures of EFV/GM and GM/THP, in addition to eutectic mixtures of EFV, GM and THP using FT-IR, DSC and WAXS revealed no potential interactions between EFV and the lipids selected for the production of the nanocarriers.
- Full Text:
- Date Issued: 2020
Prioritising African perspectives in psychiatric genomics research
- Kamaara, Eunice, Kong, Camillia, Campbell, Megan
- Authors: Kamaara, Eunice , Kong, Camillia , Campbell, Megan
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302520 , vital:58204 , xlink:href="https://doi.org/10.1111/dewb.12248"
- Description: Psychiatric genomics research with African populations comes with a range of practical challenges around translation of psychiatric genomics research concepts, procedures, and nosology. These challenges raise deep ethical issues particularly around legitimacy of informed consent, a core foundation of research ethics. Through aconsideration of the constitutive function of language, the paper problematises like‐for‐like, designative translations which often involve the ‘indigenization’ of English terms or use of metaphors which misrepresent the risks and benefits of research. This paper argues that effective translation of psychiatric genomics research terminology in African contexts demands substantive engagement with African conceptual schemas and values. In developing attenuated forms of translational thinking, researchers may recognise the deeper motivational reasons behind participation in research, highlighting the possibility that such reasons may depart from the original meaning implied within informed consent forms. These translational issues might be ameliorated with a critical re-examination of how researchers develop and present protocols to institutional ethics review boards.
- Full Text:
- Date Issued: 2020
- Authors: Kamaara, Eunice , Kong, Camillia , Campbell, Megan
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302520 , vital:58204 , xlink:href="https://doi.org/10.1111/dewb.12248"
- Description: Psychiatric genomics research with African populations comes with a range of practical challenges around translation of psychiatric genomics research concepts, procedures, and nosology. These challenges raise deep ethical issues particularly around legitimacy of informed consent, a core foundation of research ethics. Through aconsideration of the constitutive function of language, the paper problematises like‐for‐like, designative translations which often involve the ‘indigenization’ of English terms or use of metaphors which misrepresent the risks and benefits of research. This paper argues that effective translation of psychiatric genomics research terminology in African contexts demands substantive engagement with African conceptual schemas and values. In developing attenuated forms of translational thinking, researchers may recognise the deeper motivational reasons behind participation in research, highlighting the possibility that such reasons may depart from the original meaning implied within informed consent forms. These translational issues might be ameliorated with a critical re-examination of how researchers develop and present protocols to institutional ethics review boards.
- Full Text:
- Date Issued: 2020
Production, purification and characterization of a multifunctional, thermostable and acido/alkaline stable putative xylanase from the psychrotrophic bacterium, Sphingomonas aerolata
- Authors: Mathibe, Brian Nkanyiso
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164478 , vital:41122
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mathibe, Brian Nkanyiso
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164478 , vital:41122
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
Prospects for the biological control of Iris pseudacorus L(Iridaceae)
- Minuti, Gianmarco, Coetzee, Julie A, Ngxande-Koza, Samella, Hill, Martin P, Stiers, Iris
- Authors: Minuti, Gianmarco , Coetzee, Julie A , Ngxande-Koza, Samella , Hill, Martin P , Stiers, Iris
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417776 , vital:71485 , xlink:href="https://doi.org/10.1080/09583157.2020.1853050"
- Description: Native to Europe, North Africa and western Asia, Iris pseudacorus L. (Iridaceae) has invaded natural and human-modified wetlands worldwide. This species is considered a noxious weed in several countries including Argentina, South Africa and New Zealand. Its broad ecological tolerance, high resilience and reproductive potential make current mechanical and chemical control measures cost-ineffective, and biological control is considered a suitable alternative. In order to prioritise candidate biocontrol agents, a list of organisms reported to attack the plant within its native range has been assembled, and information about their host-range and damaging potential gathered from the literature. Furthermore, surveys for natural enemies of the plant were conducted in Belgium and northern Italy. The insect fauna associated with I. pseudacorus at the sites surveyed comprised mostly incidental visitors and polyphagous feeders, with the exception of the sawfly Rhadinoceraea micans Klug (Hymenoptera: Tenthredinidae), the seed weevil Mononychus punctumalbum Herbst (Coleoptera: Curculionidae), and the flea beetle Aphthona nonstriata Goeze (Coleoptera: Chrysomelidae). The potential of these species for biocontrol was evaluated, and A. nonstriata was given highest priority. A population of this species was imported to quarantine in South Africa, where it is currently undergoing host-specificity testing. Importation of the two remaining candidates is expected shortly. In conclusion, the prospects for the biological control of I. pseudacorus appear promising.
- Full Text:
- Date Issued: 2020
- Authors: Minuti, Gianmarco , Coetzee, Julie A , Ngxande-Koza, Samella , Hill, Martin P , Stiers, Iris
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417776 , vital:71485 , xlink:href="https://doi.org/10.1080/09583157.2020.1853050"
- Description: Native to Europe, North Africa and western Asia, Iris pseudacorus L. (Iridaceae) has invaded natural and human-modified wetlands worldwide. This species is considered a noxious weed in several countries including Argentina, South Africa and New Zealand. Its broad ecological tolerance, high resilience and reproductive potential make current mechanical and chemical control measures cost-ineffective, and biological control is considered a suitable alternative. In order to prioritise candidate biocontrol agents, a list of organisms reported to attack the plant within its native range has been assembled, and information about their host-range and damaging potential gathered from the literature. Furthermore, surveys for natural enemies of the plant were conducted in Belgium and northern Italy. The insect fauna associated with I. pseudacorus at the sites surveyed comprised mostly incidental visitors and polyphagous feeders, with the exception of the sawfly Rhadinoceraea micans Klug (Hymenoptera: Tenthredinidae), the seed weevil Mononychus punctumalbum Herbst (Coleoptera: Curculionidae), and the flea beetle Aphthona nonstriata Goeze (Coleoptera: Chrysomelidae). The potential of these species for biocontrol was evaluated, and A. nonstriata was given highest priority. A population of this species was imported to quarantine in South Africa, where it is currently undergoing host-specificity testing. Importation of the two remaining candidates is expected shortly. In conclusion, the prospects for the biological control of I. pseudacorus appear promising.
- Full Text:
- Date Issued: 2020
Reimagining academic identities in response to research demands at Universities of Technology
- Gumbi, Thobani, McKenna, Sioux
- Authors: Gumbi, Thobani , McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185897 , vital:44446 , xlink:href="https://doi.org/10.14426/cristal.v8i1.234"
- Description: In the last volume of this journal, Garraway and Winberg called for a reimagination of Universities of Technology (UoT) within the South African higher education system. This article continues that conversation by looking at the implications that the formation of the UoT had for academics’ identities. Technikon lecturers’ identities were closely tied to workplace expertise, but demands for research in UoTs have changed this. A social realist analysis of interviews with fifteen academics at three UoTs finds that research remains a contested issue. Interviewees understood research to take the form of acquiring postgraduate qualifications, rather than as an ongoing activity tied to their identities. Echoing Garraway and Winberg’s study, the bureaucratic nature of the institutional culture was referred to as a constraint. There was also a view that for this programme, Dental Technology, a demand for research was needed from industry if this was to be a valued aspect of academics’ identities.
- Full Text:
- Date Issued: 2020
- Authors: Gumbi, Thobani , McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185897 , vital:44446 , xlink:href="https://doi.org/10.14426/cristal.v8i1.234"
- Description: In the last volume of this journal, Garraway and Winberg called for a reimagination of Universities of Technology (UoT) within the South African higher education system. This article continues that conversation by looking at the implications that the formation of the UoT had for academics’ identities. Technikon lecturers’ identities were closely tied to workplace expertise, but demands for research in UoTs have changed this. A social realist analysis of interviews with fifteen academics at three UoTs finds that research remains a contested issue. Interviewees understood research to take the form of acquiring postgraduate qualifications, rather than as an ongoing activity tied to their identities. Echoing Garraway and Winberg’s study, the bureaucratic nature of the institutional culture was referred to as a constraint. There was also a view that for this programme, Dental Technology, a demand for research was needed from industry if this was to be a valued aspect of academics’ identities.
- Full Text:
- Date Issued: 2020
Relational hubs for collaborative landscape stewardship
- Cockburn, Jessica, Cundill, Georgina, Shackleton, Sheona, Cele, Ayanda, Cornelius, Susanna F, Koopman, Vaughan, Le Roux, Jean-Pierre, McLeod, Nicky, Rouget, Mathieu, Schroder, Samantha, Van den Broek, Dieter, Wright, Dale R, Zwinkelse, Marijn
- Authors: Cockburn, Jessica , Cundill, Georgina , Shackleton, Sheona , Cele, Ayanda , Cornelius, Susanna F , Koopman, Vaughan , Le Roux, Jean-Pierre , McLeod, Nicky , Rouget, Mathieu , Schroder, Samantha , Van den Broek, Dieter , Wright, Dale R , Zwinkelse, Marijn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392748 , vital:68789 , xlink:href="https://doi.org/10.1080/08941920.2019.1658141"
- Description: Landscape stewardship is considered an important place-based approach to addressing sustainability challenges. Working at landscape-level requires collaboration between diverse landscape stakeholders. In this study, we partnered with local stewardship practitioners across six cases in South Africa to investigate how they facilitate collaboration towards social-ecological sustainability outcomes. We found that practitioners facilitate collaboration among stakeholders by operating as relational hubs in the landscape. Through these hubs, they build new inter-personal relationships among stakeholders, creating social networks which enable stewardship practice. The hubs deepen human-nature relationships by creating enabling conditions for stewards to put stewardship ethics into action. Drawing on insights from these cases, we call for a relational approach to landscape stewardship which focuses on human-to-human and human-to-nature relationships. Moreover, we argue that landscape stewardship initiatives need to re-focus stewardship on stewards, recognizing them as key agents of change in addressing the conflict between agriculture and conservation inherent in many landscapes.
- Full Text:
- Date Issued: 2020
- Authors: Cockburn, Jessica , Cundill, Georgina , Shackleton, Sheona , Cele, Ayanda , Cornelius, Susanna F , Koopman, Vaughan , Le Roux, Jean-Pierre , McLeod, Nicky , Rouget, Mathieu , Schroder, Samantha , Van den Broek, Dieter , Wright, Dale R , Zwinkelse, Marijn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392748 , vital:68789 , xlink:href="https://doi.org/10.1080/08941920.2019.1658141"
- Description: Landscape stewardship is considered an important place-based approach to addressing sustainability challenges. Working at landscape-level requires collaboration between diverse landscape stakeholders. In this study, we partnered with local stewardship practitioners across six cases in South Africa to investigate how they facilitate collaboration towards social-ecological sustainability outcomes. We found that practitioners facilitate collaboration among stakeholders by operating as relational hubs in the landscape. Through these hubs, they build new inter-personal relationships among stakeholders, creating social networks which enable stewardship practice. The hubs deepen human-nature relationships by creating enabling conditions for stewards to put stewardship ethics into action. Drawing on insights from these cases, we call for a relational approach to landscape stewardship which focuses on human-to-human and human-to-nature relationships. Moreover, we argue that landscape stewardship initiatives need to re-focus stewardship on stewards, recognizing them as key agents of change in addressing the conflict between agriculture and conservation inherent in many landscapes.
- Full Text:
- Date Issued: 2020
Repurposing a polymer precursor scaffold for medicinal application: Synthesis, characterization and biological evaluation of ferrocenyl 1,3-benzoxazine derivatives as potential antiprotozoal and anticancer agents
- Authors: Mbaba, Mziyanda
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164502 , vital:41124 , DOI 10.21504/10962/164502
- Description: The benzoxazines are a prominent class of heterocyclic compounds that possess a multitude of properties. To this end, benzoxazine derivatives have been used as versatile compounds for various utilities ranging from biological applications to the fabrication of polymers. Particularly, the 1,3-benzoxazine scaffold has featured in several bioactive compounds showing antimalarial, anticancer and antibacterial activities. Traditionally, it has been employed as a substrate in the synthesis of polymers with appealing physical and chemical properties. Due to the increasing interest in the polymer application of 1,3-benzoxazines, research of the 1,3-benzoxazine motif for polymer synthesis has been prioritized over other applications including its medicinal potential. The continuous development of resistance to clinical anticancer and antimalarial drugs has necessitated the need for the search of innovative bioactive compounds as potential alternative medicinal agents. To address this, the field of medicinal chemistry is adapting new approaches to counter resistance by incorporating nonconventional chemical moieties such as organometallic complexes, like ferrocene, into bioactive chemical motifs to serve as novel compounds with medicinal benefits. Incorporation of ferrocene into known bioactive chemical moieties has been shown to impart beneficial biological effects into the resultant compounds, which include the introduction of novel, and sometimes varied, mechanistic modalities and enhanced potency. Presented with the benefits of this strategy, the current work aims to design and evaluate the pharmaceutical capacity of novel derivatives containing 1,3-benzoxazine scaffold (traditionally applied in polymer synthesis) hybridized with the organometallic ferrocene unit as bioactive agents. Using a combination of expedient synthetic procedures such as the Burke three-component Mannich-type condensation, Vilsmeier-Haack formylation and reductive amination, four series of ferrocenyl 1,3-benzoxazine derivatives were synthesized and their structures confirmed by common spectroscopic techniques: nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and high-resolution mass spectrometry (HRMS). The target compounds were evaluated in vitro for potential antimalarial and anticancer activities against strains of the malaria parasite (Plasmodium falciparum 3D7 and Dd2) and the triple-negative breast cancer cell line HCC70. Compounds exhibited higher potency towards the Plasmodium falciparum strains with IC50 values in the low and sub-micromolar range in comparison to the breast cancer cell line against for which mid-molar activities were observed. To gain insight into the possible mode of action of ferrocenyl 1,3-benzoxazines, representative compounds showing most efficacy from each series were assessed for DNA binding affinity by employing UV-Vis and fluorescence DNA titration experiments. The selected compounds were found to interact with the DNA by binding to the minor groove, and these findings were confirmed by in silico ligand docking studies using a B-DNA structure as the receptor. Compound 3.16c (IC50: 0.261 μM [3D7], 0.599 μM [Dd2], 11.0 μM [HCC70]), which emerged as the most promising compound, was found to induce DNA damage in HCC70 cancer cells when investigated for effects of DNA interaction. Additionally, compound 3.16c displayed a higher binding constant (Kb) against DNA isolated from 3D7 Plasmodium falciparum trophozoites (Kb = 1.88×106 M-1) than the mammalian DNA (Kb = 6.33×104 M-1) from calf thymus, thus explaining the preferred selectivity of the compounds for the malaria parasite. Moreover, the investigated compounds demonstrated binding affinity for synthetic hemozoin, β-hematin. Collectively, these data suggest that the compounds possess a dual mode of action for antimalarial activity involving DNA interaction and hemozoin inhibition. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mbaba, Mziyanda
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164502 , vital:41124 , DOI 10.21504/10962/164502
- Description: The benzoxazines are a prominent class of heterocyclic compounds that possess a multitude of properties. To this end, benzoxazine derivatives have been used as versatile compounds for various utilities ranging from biological applications to the fabrication of polymers. Particularly, the 1,3-benzoxazine scaffold has featured in several bioactive compounds showing antimalarial, anticancer and antibacterial activities. Traditionally, it has been employed as a substrate in the synthesis of polymers with appealing physical and chemical properties. Due to the increasing interest in the polymer application of 1,3-benzoxazines, research of the 1,3-benzoxazine motif for polymer synthesis has been prioritized over other applications including its medicinal potential. The continuous development of resistance to clinical anticancer and antimalarial drugs has necessitated the need for the search of innovative bioactive compounds as potential alternative medicinal agents. To address this, the field of medicinal chemistry is adapting new approaches to counter resistance by incorporating nonconventional chemical moieties such as organometallic complexes, like ferrocene, into bioactive chemical motifs to serve as novel compounds with medicinal benefits. Incorporation of ferrocene into known bioactive chemical moieties has been shown to impart beneficial biological effects into the resultant compounds, which include the introduction of novel, and sometimes varied, mechanistic modalities and enhanced potency. Presented with the benefits of this strategy, the current work aims to design and evaluate the pharmaceutical capacity of novel derivatives containing 1,3-benzoxazine scaffold (traditionally applied in polymer synthesis) hybridized with the organometallic ferrocene unit as bioactive agents. Using a combination of expedient synthetic procedures such as the Burke three-component Mannich-type condensation, Vilsmeier-Haack formylation and reductive amination, four series of ferrocenyl 1,3-benzoxazine derivatives were synthesized and their structures confirmed by common spectroscopic techniques: nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and high-resolution mass spectrometry (HRMS). The target compounds were evaluated in vitro for potential antimalarial and anticancer activities against strains of the malaria parasite (Plasmodium falciparum 3D7 and Dd2) and the triple-negative breast cancer cell line HCC70. Compounds exhibited higher potency towards the Plasmodium falciparum strains with IC50 values in the low and sub-micromolar range in comparison to the breast cancer cell line against for which mid-molar activities were observed. To gain insight into the possible mode of action of ferrocenyl 1,3-benzoxazines, representative compounds showing most efficacy from each series were assessed for DNA binding affinity by employing UV-Vis and fluorescence DNA titration experiments. The selected compounds were found to interact with the DNA by binding to the minor groove, and these findings were confirmed by in silico ligand docking studies using a B-DNA structure as the receptor. Compound 3.16c (IC50: 0.261 μM [3D7], 0.599 μM [Dd2], 11.0 μM [HCC70]), which emerged as the most promising compound, was found to induce DNA damage in HCC70 cancer cells when investigated for effects of DNA interaction. Additionally, compound 3.16c displayed a higher binding constant (Kb) against DNA isolated from 3D7 Plasmodium falciparum trophozoites (Kb = 1.88×106 M-1) than the mammalian DNA (Kb = 6.33×104 M-1) from calf thymus, thus explaining the preferred selectivity of the compounds for the malaria parasite. Moreover, the investigated compounds demonstrated binding affinity for synthetic hemozoin, β-hematin. Collectively, these data suggest that the compounds possess a dual mode of action for antimalarial activity involving DNA interaction and hemozoin inhibition. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Date Issued: 2020
Screening for small molecule modulators of Trypanosoma brucei Hsp70 chaperone activity based upon alcyonarian coral-derived natural products
- Andreassend, Sarah K, Bentley, Stephen, Blatch, Gregory L, Boshoff, Aileen, Keyzers, Robert A
- Authors: Andreassend, Sarah K , Bentley, Stephen , Blatch, Gregory L , Boshoff, Aileen , Keyzers, Robert A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426045 , vital:72309 , xlink:href="https://doi.org/10.3390/md18020081"
- Description: The Trypanosoma brucei Hsp70/J-protein machinery plays an essential role in survival, differentiation, and pathogenesis of the protozoan parasite, and is an emerging target against African Trypanosomiasis. This study evaluated a set of small molecules, inspired by the malonganenones and nuttingins, as modulators of the chaperone activity of the cytosolic heat inducible T. brucei Hsp70 and constitutive TbHsp70.4 proteins. The compounds were assessed for cytotoxicity on both the bloodstream form of T. b. brucei parasites and a mammalian cell line. The compounds were then investigated for their modulatory effect on the aggregation suppression and ATPase activities of the TbHsp70 proteins. A structure–activity relationship for the malonganenone-class of alkaloids is proposed based upon these results.
- Full Text:
- Date Issued: 2020
- Authors: Andreassend, Sarah K , Bentley, Stephen , Blatch, Gregory L , Boshoff, Aileen , Keyzers, Robert A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426045 , vital:72309 , xlink:href="https://doi.org/10.3390/md18020081"
- Description: The Trypanosoma brucei Hsp70/J-protein machinery plays an essential role in survival, differentiation, and pathogenesis of the protozoan parasite, and is an emerging target against African Trypanosomiasis. This study evaluated a set of small molecules, inspired by the malonganenones and nuttingins, as modulators of the chaperone activity of the cytosolic heat inducible T. brucei Hsp70 and constitutive TbHsp70.4 proteins. The compounds were assessed for cytotoxicity on both the bloodstream form of T. b. brucei parasites and a mammalian cell line. The compounds were then investigated for their modulatory effect on the aggregation suppression and ATPase activities of the TbHsp70 proteins. A structure–activity relationship for the malonganenone-class of alkaloids is proposed based upon these results.
- Full Text:
- Date Issued: 2020
Screening of ectomycorrhizal and other associated fungi in South African forest nurseries
- Chartier FitzGerald , Veronique, Dames, Joanna F, Hawley, Greer L
- Authors: Chartier FitzGerald , Veronique , Dames, Joanna F , Hawley, Greer L
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426058 , vital:72310 , xlink:href="https://hdl.handle.net/10520/ejc-soufor-v82-n4-a8"
- Description: The South African forestry industry covers approximately 1.3 million hectares and is dependent on exotic pine and eucalypt species. Nursery seedlings are not inoculated with ectomycorrhizal (ECM) fungi. This investigation assessed levels of naturally occurring ECM colonisation of Pinus patula seedlings from 10 different South African forestry nurseries using a grid line intersect method. Fungi from colonised roots were identified using morphological characteristics and Illumina sequencing. Colonisation of seedlings in production nurseries was low (2-21%). Morphologically, the ECM fungi Thelophora terrestris, Suillus sibiricus, and the genera Russula and Pseudotomentella were identified. Molecularly, the ECM fungi T. terrestris, Inocybe jacobi and the genus Sphaerosporella, as well as several other ECM-containing families were identified, along with many saprotrophic/ endophytic fungi belonging to genera such as Penicillium, Ramasonia and Talaromyces. As can be seen, a combination of both molecular and morphological identification techniques are needed as neither is able to give a full picture of the species present in isolation. This study reveals an initial insight into the root microbiome community associated with Pinus patula seedlings, which should be taken into account when inoculation with beneficial microbes is considered. It determined that natural ECM fungal root colonisation levels are very low throughout the South African nurseries investigated, indicating the need for ECM fungal inoculation, which can increase seedling growth, viability and resistance to pathogens.
- Full Text:
- Date Issued: 2020
- Authors: Chartier FitzGerald , Veronique , Dames, Joanna F , Hawley, Greer L
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426058 , vital:72310 , xlink:href="https://hdl.handle.net/10520/ejc-soufor-v82-n4-a8"
- Description: The South African forestry industry covers approximately 1.3 million hectares and is dependent on exotic pine and eucalypt species. Nursery seedlings are not inoculated with ectomycorrhizal (ECM) fungi. This investigation assessed levels of naturally occurring ECM colonisation of Pinus patula seedlings from 10 different South African forestry nurseries using a grid line intersect method. Fungi from colonised roots were identified using morphological characteristics and Illumina sequencing. Colonisation of seedlings in production nurseries was low (2-21%). Morphologically, the ECM fungi Thelophora terrestris, Suillus sibiricus, and the genera Russula and Pseudotomentella were identified. Molecularly, the ECM fungi T. terrestris, Inocybe jacobi and the genus Sphaerosporella, as well as several other ECM-containing families were identified, along with many saprotrophic/ endophytic fungi belonging to genera such as Penicillium, Ramasonia and Talaromyces. As can be seen, a combination of both molecular and morphological identification techniques are needed as neither is able to give a full picture of the species present in isolation. This study reveals an initial insight into the root microbiome community associated with Pinus patula seedlings, which should be taken into account when inoculation with beneficial microbes is considered. It determined that natural ECM fungal root colonisation levels are very low throughout the South African nurseries investigated, indicating the need for ECM fungal inoculation, which can increase seedling growth, viability and resistance to pathogens.
- Full Text:
- Date Issued: 2020
Sn (iv) N-confused porphyrins as photosensitizer dyes for photodynamic therapy in the near IR region
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186648 , vital:44521 , xlink:href="https://doi.org/10.1039/D0DT03296D"
- Description: The utility of Sn(IV) N-confused porphyrin (SnNCP) for use as photosensitizer dyes in photodynamic therapy is investigated. SnNCP has an unusually high singlet oxygen quantum yield of 0.72 in DMSO. IC50 values of 1.6 and 12.8 μM were obtained against MCF-7 cells upon irradiation with 660 and 780 nm LEDs.
- Full Text:
- Date Issued: 2020
Sn (iv) N-confused porphyrins as photosensitizer dyes for photodynamic therapy in the near IR region
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186648 , vital:44521 , xlink:href="https://doi.org/10.1039/D0DT03296D"
- Description: The utility of Sn(IV) N-confused porphyrin (SnNCP) for use as photosensitizer dyes in photodynamic therapy is investigated. SnNCP has an unusually high singlet oxygen quantum yield of 0.72 in DMSO. IC50 values of 1.6 and 12.8 μM were obtained against MCF-7 cells upon irradiation with 660 and 780 nm LEDs.
- Full Text:
- Date Issued: 2020
Softboi
- Authors: Mall, Shireen
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164373 , vital:41113
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mall, Shireen
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164373 , vital:41113
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2020
- Full Text:
- Date Issued: 2020
Substituent effect on the photophysical and nonlinear optical characteristics of Si phthalocyanine–Detonated nanodiamond conjugated systems in solution
- Matshitse, Refilwe, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186293 , vital:44482 , xlink:href="https://doi.org/10.1016/j.ica.2020.119447"
- Description: This work reports on the photophysical, nonlinear absorption and optical limiting properties of detonation nanodiamonds (DNDs)-silicon phthalocyanine nanoconjugate systems. Si(IV) hydroxide phthalocyanines employed are: 2,9(10),16(17),23(24)-tetrakis-(4-pyridyloxy) phthalocyaninato (Si(OH)2TPPc), 2,9(10),16(17),23(24)-tetrakis-(4-tert-butyl) phthalocyanato (Si(OH)2TBPc) and phthalocyanato(Si(OH)2Pc). Pcs were covalently linked to nanondiamonds and investigated using 532 nm laser excitation at 7 ns pulses for their optical limiting properties. Si(OH)2TBPc and Si(OH)2Pc gave larger triplet quantum yields when linked to DNDs, while the value decreased for Si(OH)2TPPc in the presence of DNDs due to aggregation. However all Pcs showed enhanced nonlinear optical properties in the presence of DNDs. DNDs-Si(OH)2TPPc and DNDs-Si (OH)2TBPc gave the highest imaginary third-order susceptibility (Im[X(3)]) and hyperpolarizability (γ) at 5.19 × 10−8 and 3.85 × 10−8 esu and 2.66 × 10−27 and 1.97 × 10−27 esu, respectively. DNDs-Si(OH)2TBPc nanoconjugates showed lowest limiting threshold (Ilim) value of 0.01 J.cm−2 relative to 0.09 for DNDs-Si (OH)2TPPc.
- Full Text:
- Date Issued: 2020
- Authors: Matshitse, Refilwe , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186293 , vital:44482 , xlink:href="https://doi.org/10.1016/j.ica.2020.119447"
- Description: This work reports on the photophysical, nonlinear absorption and optical limiting properties of detonation nanodiamonds (DNDs)-silicon phthalocyanine nanoconjugate systems. Si(IV) hydroxide phthalocyanines employed are: 2,9(10),16(17),23(24)-tetrakis-(4-pyridyloxy) phthalocyaninato (Si(OH)2TPPc), 2,9(10),16(17),23(24)-tetrakis-(4-tert-butyl) phthalocyanato (Si(OH)2TBPc) and phthalocyanato(Si(OH)2Pc). Pcs were covalently linked to nanondiamonds and investigated using 532 nm laser excitation at 7 ns pulses for their optical limiting properties. Si(OH)2TBPc and Si(OH)2Pc gave larger triplet quantum yields when linked to DNDs, while the value decreased for Si(OH)2TPPc in the presence of DNDs due to aggregation. However all Pcs showed enhanced nonlinear optical properties in the presence of DNDs. DNDs-Si(OH)2TPPc and DNDs-Si (OH)2TBPc gave the highest imaginary third-order susceptibility (Im[X(3)]) and hyperpolarizability (γ) at 5.19 × 10−8 and 3.85 × 10−8 esu and 2.66 × 10−27 and 1.97 × 10−27 esu, respectively. DNDs-Si(OH)2TBPc nanoconjugates showed lowest limiting threshold (Ilim) value of 0.01 J.cm−2 relative to 0.09 for DNDs-Si (OH)2TPPc.
- Full Text:
- Date Issued: 2020
Susceptibility of Staphylococcus aureus to porphyrin-silver nanoparticle mediated photodynamic antimicrobial chemotherapy
- Shabangu, Samuel M, Babu, Balaji, Soy, Rodah C, Ovim, James, Amuhaya, Edith, Nyokong, Tebello
- Authors: Shabangu, Samuel M , Babu, Balaji , Soy, Rodah C , Ovim, James , Amuhaya, Edith , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186262 , vital:44479 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117158"
- Description: Photodynamic antimicrobial chemotherapy (PACT) is employed against multi drug resistant Staphylococcus aureus using porphyrins combined with silver nanoparticles to bring about a combined photodynamic effect. We employ Zn-meso-5,10,15,20-tetra(4-pyridyl) (1), Zn-meso-5,10,15,20-tetrathienyl (2), and Zn-meso-5-(4- hydroxyphenyl)- 10,15,20-tris(2-thienyl)(3) porphyrins and their self-assembled conjugates with silver nanoparticles for PACT against Staphylococcus aureus. Complex 3 with nanoparticles was found to perform better resulting in 0% bacterial viability at 60 min.
- Full Text:
- Date Issued: 2020
- Authors: Shabangu, Samuel M , Babu, Balaji , Soy, Rodah C , Ovim, James , Amuhaya, Edith , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186262 , vital:44479 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117158"
- Description: Photodynamic antimicrobial chemotherapy (PACT) is employed against multi drug resistant Staphylococcus aureus using porphyrins combined with silver nanoparticles to bring about a combined photodynamic effect. We employ Zn-meso-5,10,15,20-tetra(4-pyridyl) (1), Zn-meso-5,10,15,20-tetrathienyl (2), and Zn-meso-5-(4- hydroxyphenyl)- 10,15,20-tris(2-thienyl)(3) porphyrins and their self-assembled conjugates with silver nanoparticles for PACT against Staphylococcus aureus. Complex 3 with nanoparticles was found to perform better resulting in 0% bacterial viability at 60 min.
- Full Text:
- Date Issued: 2020
Synergistic effects of temperature and plant quality, on development time, size and lipid in Eccritotarsus eichhorniae
- Ismail, Mohannad, Brooks, Margot, Van Baaren, Joan, Albittar, Loulou
- Authors: Ismail, Mohannad , Brooks, Margot , Van Baaren, Joan , Albittar, Loulou
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426078 , vital:72312 , xlink:href="https://doi.org/10.1111/jen.12841"
- Description: Body size is an important biotic factor in evolutionary ecology, since it affects all aspects of insect physiology, life history and, consequently, fitness in ectothermic insects and how species adapt with their environment. It has been linked to tem-perature, with lower temperatures resulting in larger size. In this study, we tested the combined impact of temperature and plant quality on the body size, and de-velopment time from egg to adult of Eccritotarsus eichhorniae (Hemiptera: Miridae), an herbivorous insect used as a biological control agent against the invasive aquatic weed, water hyacinth Eichhornia crassipes (Pontederiaceae). We quantified insect size in individuals exposed to three temperatures (20, 25 and 30°C) combined with three qualities of host plant (high, medium and low) by calculating development time and measuring four traits: tibia length, forewing length, dry body mass and lipid con-tent, and we also determined the wing loading index. The development time, dry body mass and lipid content decreased linearly with increasing temperature and de-creasing plant quality. The decrease in size was the greatest when high temperature interacted with low plant quality. Smaller individuals had proportionately less lipid content. Wing loading decreased significantly with lower quality of host plant, result-ing in individuals likely to have theoretically higher flight ability. The results support the temperature-size rule (TSR) and that plant quality could influence the relationship between development time and the TSR. Results also provide novel evidence for a possible food quality-size rule for both sexes.
- Full Text:
- Date Issued: 2020
- Authors: Ismail, Mohannad , Brooks, Margot , Van Baaren, Joan , Albittar, Loulou
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426078 , vital:72312 , xlink:href="https://doi.org/10.1111/jen.12841"
- Description: Body size is an important biotic factor in evolutionary ecology, since it affects all aspects of insect physiology, life history and, consequently, fitness in ectothermic insects and how species adapt with their environment. It has been linked to tem-perature, with lower temperatures resulting in larger size. In this study, we tested the combined impact of temperature and plant quality on the body size, and de-velopment time from egg to adult of Eccritotarsus eichhorniae (Hemiptera: Miridae), an herbivorous insect used as a biological control agent against the invasive aquatic weed, water hyacinth Eichhornia crassipes (Pontederiaceae). We quantified insect size in individuals exposed to three temperatures (20, 25 and 30°C) combined with three qualities of host plant (high, medium and low) by calculating development time and measuring four traits: tibia length, forewing length, dry body mass and lipid con-tent, and we also determined the wing loading index. The development time, dry body mass and lipid content decreased linearly with increasing temperature and de-creasing plant quality. The decrease in size was the greatest when high temperature interacted with low plant quality. Smaller individuals had proportionately less lipid content. Wing loading decreased significantly with lower quality of host plant, result-ing in individuals likely to have theoretically higher flight ability. The results support the temperature-size rule (TSR) and that plant quality could influence the relationship between development time and the TSR. Results also provide novel evidence for a possible food quality-size rule for both sexes.
- Full Text:
- Date Issued: 2020
Synthesis and biological evaluation of bis-N2, N2′-(4-hydroxycoumarin-3-yl) ethylidene]-2, 3-dihydroxysuccinodihydrazides
- Manyeruke, Meloddy H, Tshiwawa, Thendamudzimu, Hoppe, Heinrich, Isaacs, Michelle, Seldon, Ronnett, Warner, Digby F, Krause, Rui W M, Kaye, Perry T
- Authors: Manyeruke, Meloddy H , Tshiwawa, Thendamudzimu , Hoppe, Heinrich , Isaacs, Michelle , Seldon, Ronnett , Warner, Digby F , Krause, Rui W M , Kaye, Perry T
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193430 , vital:45331 , xlink:href="https://doi.org/10.1016/j.bmcl.2019.126911"
- Description: A series of N2,N2′-bis[4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccino-hydrazides, containing 4-hydroxycoumarin, hydrazine and tartaric acid moieties, have been prepared and examined for possible biological activity. Several of these compounds exhibit promising HIV-1 integrase inhibition (IC50 = 3.5 μM), and anti-T. brucei (32% viability) and anti-mycobacterial (Visual MIC90 = 15.63 μM) activity.
- Full Text:
- Date Issued: 2020
- Authors: Manyeruke, Meloddy H , Tshiwawa, Thendamudzimu , Hoppe, Heinrich , Isaacs, Michelle , Seldon, Ronnett , Warner, Digby F , Krause, Rui W M , Kaye, Perry T
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193430 , vital:45331 , xlink:href="https://doi.org/10.1016/j.bmcl.2019.126911"
- Description: A series of N2,N2′-bis[4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccino-hydrazides, containing 4-hydroxycoumarin, hydrazine and tartaric acid moieties, have been prepared and examined for possible biological activity. Several of these compounds exhibit promising HIV-1 integrase inhibition (IC50 = 3.5 μM), and anti-T. brucei (32% viability) and anti-mycobacterial (Visual MIC90 = 15.63 μM) activity.
- Full Text:
- Date Issued: 2020
Synthesis and in vitro biological evaluation of 2,3-substituted quinoline derivatives
- Bokosi, Fostino Raphael Bentry
- Authors: Bokosi, Fostino Raphael Bentry
- Date: 2020
- Subjects: Quinoline , Malaria Chemotherapy , Tuberculosis Chemotherapy , African trypanosomiasis Chemotherapy
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/163193 , vital:41017
- Description: The urgent need for new systemic pharmacological entities prompted us to report a library of 2,3-substituted quinoline derivatives. Considering the ubiquity of quinoline-containing compounds in pharmacologically active small molecules, synthesized 2,3-substituted quinoline derivatives were in vitro biologically evaluated for their potential antitubercular, antimalarial and antitrypanosomal activities. Quinoline scaffold was achieved by the Vilsmeier-Haack methodology, affording synthetically useful chloro and formyl substituents on C-2 and C-3 respectively. These two substituents acted as handles in expanding the chemical space around the quinoline ring. Target compounds were synthesized in six to seven steps, employing conventional synthetic organic protocols adapted from various literature. The final compounds were accessed in moderate to good yields. The structural identity of each compound was confirmed by common spectroscopic techniques. Aryl quinoline carboxamide derivatives 3.113 – 3.126 were isolated as rotamers, hence, Variable-Temperature Nuclear Magnetic Resonance (VT-NMR) was employed in resolving 1H splitting. At elevated temperature (~328 K); N-methylene carbons were not visible on 13C NMR due to signal line broadening effects. The presence of these nuclei in such cases was, however, supported by 2-dimensional NMR and high-resolution MS data. Most of the compounds achieved in this study displayed promising antimalarial activity against chloroquine-sensitive 3D7 strain of Plasmodium falciparum compared to antitrypanosomal activity against Trypanosoma brucei brucei 427 strain. In particular, compounds 3.80 and 3.108 showed superior activity against chloroquine-sensitive 3D7 P. falciparum strain with IC50 values < 1 μM. More importantly, most of the compounds were non-toxic as determined by HeLa cells, indicating their selectivity towards the parasites. Exploring the space provided on the quinoline scaffold revealed that methoxy incorporation on C-2 is very critical in enhancing antimalarial activity of this class of quinoline compounds. The preliminary SAR of compounds 3.57 – 3.72 showed that compounds containing the 3-cinnamate exhibited enhanced antimalarial activity compared to 2 and 4-cinnamates. Finally, benzamide compounds 3.113 − 3.126 showed poor activity against Mycobacterium tuberculosis H37Rv strain with only compounds 3.113, 3.117 – 3.120 and 3.126 showing appreciable MIC90 values in the range of 40 – 85 μM. , Thesis (MSc) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Date Issued: 2020
- Authors: Bokosi, Fostino Raphael Bentry
- Date: 2020
- Subjects: Quinoline , Malaria Chemotherapy , Tuberculosis Chemotherapy , African trypanosomiasis Chemotherapy
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/163193 , vital:41017
- Description: The urgent need for new systemic pharmacological entities prompted us to report a library of 2,3-substituted quinoline derivatives. Considering the ubiquity of quinoline-containing compounds in pharmacologically active small molecules, synthesized 2,3-substituted quinoline derivatives were in vitro biologically evaluated for their potential antitubercular, antimalarial and antitrypanosomal activities. Quinoline scaffold was achieved by the Vilsmeier-Haack methodology, affording synthetically useful chloro and formyl substituents on C-2 and C-3 respectively. These two substituents acted as handles in expanding the chemical space around the quinoline ring. Target compounds were synthesized in six to seven steps, employing conventional synthetic organic protocols adapted from various literature. The final compounds were accessed in moderate to good yields. The structural identity of each compound was confirmed by common spectroscopic techniques. Aryl quinoline carboxamide derivatives 3.113 – 3.126 were isolated as rotamers, hence, Variable-Temperature Nuclear Magnetic Resonance (VT-NMR) was employed in resolving 1H splitting. At elevated temperature (~328 K); N-methylene carbons were not visible on 13C NMR due to signal line broadening effects. The presence of these nuclei in such cases was, however, supported by 2-dimensional NMR and high-resolution MS data. Most of the compounds achieved in this study displayed promising antimalarial activity against chloroquine-sensitive 3D7 strain of Plasmodium falciparum compared to antitrypanosomal activity against Trypanosoma brucei brucei 427 strain. In particular, compounds 3.80 and 3.108 showed superior activity against chloroquine-sensitive 3D7 P. falciparum strain with IC50 values < 1 μM. More importantly, most of the compounds were non-toxic as determined by HeLa cells, indicating their selectivity towards the parasites. Exploring the space provided on the quinoline scaffold revealed that methoxy incorporation on C-2 is very critical in enhancing antimalarial activity of this class of quinoline compounds. The preliminary SAR of compounds 3.57 – 3.72 showed that compounds containing the 3-cinnamate exhibited enhanced antimalarial activity compared to 2 and 4-cinnamates. Finally, benzamide compounds 3.113 − 3.126 showed poor activity against Mycobacterium tuberculosis H37Rv strain with only compounds 3.113, 3.117 – 3.120 and 3.126 showing appreciable MIC90 values in the range of 40 – 85 μM. , Thesis (MSc) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Date Issued: 2020
Synthesis and pharmacological evaluation of chlorin derivatives for photodynamic therapy of cholangiocarcinoma
- Gao, Ying-Hua, Li, Man-Yi, Saijad, Faiza, Wang, Jin-Hai, Meharban, Faiza, Gadoora, Malaz A, Yan, Yi-Jia, Nyokong, Tebello, Chen, Zhi-Long
- Authors: Gao, Ying-Hua , Li, Man-Yi , Saijad, Faiza , Wang, Jin-Hai , Meharban, Faiza , Gadoora, Malaz A , Yan, Yi-Jia , Nyokong, Tebello , Chen, Zhi-Long
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190873 , vital:45036 , xlink:href="https://doi.org/10.1016/j.ejmech.2020.112049"
- Description: Photodynamic therapy (PDT) has been developed as a promising therapeutic method in cancer treatment. The discovery of effective photosensitizer, which is the key factor of PDT, is highly desired. This paper reports the synthesis of novel chlorin derivatives, 5,10,15,20-tetraphenyl-[2:3]-[(methoxycarbonyl, carboxy)methano] chlorin I and 5,10,15,20-tetraphenyl-[2:3]- {[methoxycarbonyl, (2-hydroxyethyl)amide]methano}chlorin II. Their structures were characterized with UV–vis, 1HNMR, 13CNMR and HRMS spectroscopies. Photophysical and photochemical experiments results showed that compound I and II had an absorption maximum around 650 nm, with molar extinction coefficients of 1 × 104 M−1 cm−1. They had strong fluorescence emission in 650–660 nm upon excitation with 419–422 nm light. ESR showed that singlet oxygen was produced upon irradiation of compounds with 650 nm light in the presence of molecular oxygen. The photo-bleaching test indicated that the structure of compounds was stable. These new compounds exhibit excellent anti-tumor effects and lower toxicity compared to m-THPC in vitro and in vivo. Compound I and II had high tumor selectivity, which could induced tumor cells shrinkage and necrosis under 650 nm laser irradiation. Flow cytometry revealed that the compounds might mediate PDT effect at late apoptotic phase. These results make these compound I and II promising candidates for future study in photo-diagnosis and photodynamic therapy of cholangiocarcinoma.
- Full Text:
- Date Issued: 2020
- Authors: Gao, Ying-Hua , Li, Man-Yi , Saijad, Faiza , Wang, Jin-Hai , Meharban, Faiza , Gadoora, Malaz A , Yan, Yi-Jia , Nyokong, Tebello , Chen, Zhi-Long
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190873 , vital:45036 , xlink:href="https://doi.org/10.1016/j.ejmech.2020.112049"
- Description: Photodynamic therapy (PDT) has been developed as a promising therapeutic method in cancer treatment. The discovery of effective photosensitizer, which is the key factor of PDT, is highly desired. This paper reports the synthesis of novel chlorin derivatives, 5,10,15,20-tetraphenyl-[2:3]-[(methoxycarbonyl, carboxy)methano] chlorin I and 5,10,15,20-tetraphenyl-[2:3]- {[methoxycarbonyl, (2-hydroxyethyl)amide]methano}chlorin II. Their structures were characterized with UV–vis, 1HNMR, 13CNMR and HRMS spectroscopies. Photophysical and photochemical experiments results showed that compound I and II had an absorption maximum around 650 nm, with molar extinction coefficients of 1 × 104 M−1 cm−1. They had strong fluorescence emission in 650–660 nm upon excitation with 419–422 nm light. ESR showed that singlet oxygen was produced upon irradiation of compounds with 650 nm light in the presence of molecular oxygen. The photo-bleaching test indicated that the structure of compounds was stable. These new compounds exhibit excellent anti-tumor effects and lower toxicity compared to m-THPC in vitro and in vivo. Compound I and II had high tumor selectivity, which could induced tumor cells shrinkage and necrosis under 650 nm laser irradiation. Flow cytometry revealed that the compounds might mediate PDT effect at late apoptotic phase. These results make these compound I and II promising candidates for future study in photo-diagnosis and photodynamic therapy of cholangiocarcinoma.
- Full Text:
- Date Issued: 2020
Synthesis of novel Schiff base cobalt (II) and iron (iii) complexes as cathode catalysts for microbial fuel cell applications
- Sen, Pinar, Akagunduz, Dilan, Aghdam, Araz S, Cebeci, Fevzi C, Nyokong, Tebello, Catal, Tunc
- Authors: Sen, Pinar , Akagunduz, Dilan , Aghdam, Araz S , Cebeci, Fevzi C , Nyokong, Tebello , Catal, Tunc
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190861 , vital:45035 , xlink:href="https://doi.org/10.1007/s10904-019-01286-x"
- Description: In this study, the synthesis and characterization of a new Schiff base and its cobalt(II) and iron(III) complexes were performed fully characterized by common spectroscopic techniques such as 1H-NMR, 13C-NMR, FT-IR, UV–Vis and MS and elemental analysis. The cathodes prepared with only activated carbon, Co-Schiff base complex, and Fe-Schiff base complex mixed with activated carbon as the carrier were examined in single chamber air cathode microbial fuel cells (MFCs). The spectroscopic results confirm the structure of novel Schiff base and its complexes with cobalt (II) and Fe(III). MFC results showed that Fe-Schiff base complex generated higher voltage generation using glucose as the carbon source. Cyclic voltammetry results showed the conductivity and catalytic features of the cathodes developed in this study. Scanning electron microscopic results showed the distribution the complexes on the cathode surface. In conclusion, a novel Schiff base and its complexes with cobalt (II) and iron (III) can be employed into MFC technology to be used in green electricity production, and might help decreasing the operating costs of wastewater treatment plants.
- Full Text:
- Date Issued: 2020
- Authors: Sen, Pinar , Akagunduz, Dilan , Aghdam, Araz S , Cebeci, Fevzi C , Nyokong, Tebello , Catal, Tunc
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190861 , vital:45035 , xlink:href="https://doi.org/10.1007/s10904-019-01286-x"
- Description: In this study, the synthesis and characterization of a new Schiff base and its cobalt(II) and iron(III) complexes were performed fully characterized by common spectroscopic techniques such as 1H-NMR, 13C-NMR, FT-IR, UV–Vis and MS and elemental analysis. The cathodes prepared with only activated carbon, Co-Schiff base complex, and Fe-Schiff base complex mixed with activated carbon as the carrier were examined in single chamber air cathode microbial fuel cells (MFCs). The spectroscopic results confirm the structure of novel Schiff base and its complexes with cobalt (II) and Fe(III). MFC results showed that Fe-Schiff base complex generated higher voltage generation using glucose as the carbon source. Cyclic voltammetry results showed the conductivity and catalytic features of the cathodes developed in this study. Scanning electron microscopic results showed the distribution the complexes on the cathode surface. In conclusion, a novel Schiff base and its complexes with cobalt (II) and iron (III) can be employed into MFC technology to be used in green electricity production, and might help decreasing the operating costs of wastewater treatment plants.
- Full Text:
- Date Issued: 2020