Research Articles (Chemistry)

Permanent URI for this collectionhttp://hdl.handle.net/2263/1724

This collection contains some of the full text peer-reviewed/ refereed articles published by researchers from the Department of Chemistry

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CRISPR-Cas9 gene drive and conventional approaches for malaria control : a review of progress, challenges, and future prospects
Robinson, Ayibanuah F.; Okafor, Esther O.; Oduselu, Gbolahan O.; Opebiyi, Oluwabukayo T.; October, Natasha; Ajani, Olayinka O. (Elsevier, 2026-09)
Malaria remains a global health challenge, having a steadily increasing incidence as well as death rate, particularly in sub-Saharan Africa. Modern methods of tackling malaria, which primarily include long-lasting insecticide-treated nets (LLINs), indoor residual spraying (IRS), and antimalarial drugs, are faced with a serious threat emanating from drug and insecticide/pesticide resistance, thereby undermining eradication efforts. This work extensively reviewed the current literature on conventional means of controlling malaria to unveil the impediments to their use and the urgent need for a permanent solution through innovative strategies. It also provided a detailed evaluation of gene drive technology based on the CRISPR-Cas9 system as a crucial complementary tool for malaria control. Additionally, this present study carefully evaluated the ethical issues related to this technology, as well as the ecological concerns regarding the production and release of gene drive modified organisms. The CRISPR-Cas9 system employs a sequence-specific endonuclease mechanism to generate targeted double-strand DNA breaks, forming the basis for precise gene editing and drive development, and utilises two fundamental strategies for vector control: population suppression, primarily aimed at reducing the mosquito population, and population replacement, which aims to spread genes that make mosquitoes refractory to the Plasmodium parasite. HIGHLIGHTS • CRISPR-Cas9 gene drive technology represents a cutting-edge approach capable of achieving mosquito population suppression and population modification, ultimately eliminating malaria tr transmission. • Homing suppression drives targeting conserved genes, such as the double sex, can achieve complete cage population elimination while minimizing functional resistance allele formation. • A major biological barrier to field deployment of gene drive technology is the formation of functional resistance alleles and fitness cost. • In any field release of gene drive mosquitoes, the ecological risk assessment, ethical governance framework, and community involvement remain an indispensable prerequisite.
Stimuli-responsive aluminium-fumarate MOFs from recycled aluminium : phase evolution, thermochromism and gas sorption
Ndamyabera, Christophe Adrien; Joubert, Serena Elizabeth; Langmi, Henrietta Wakuna (South African Chemical Institute, 2026-06)
Please read abstract in the article.
Supramolecular architecture modulated by positional isomerism : synthesis, structure, and fluorescence properties of ionic systems containing 1,8-Naphthalimide derivatives and tetrahalometallate anions
Beebeejaun-Boodoo, B.M. Parveen; Kleine, Tatjana (American Chemical Society, 2026-05-13)
Please read abstract in the article.
Assessing the cytotoxic effects of Group IX metal N-heterocyclic carbene complexes of iridium and rhodium on B16-F10 melanoma and non-cancerous RAW 264.7 cells
Van Vuuren, Estefan; Nadasen, Carolyn Courtney; Malan, F.P. (Frederick); Hlophe, Yvette Nkondo; Serem, June Cheptoo; Landman, Marile (Elsevier, 2026-09-15)
The development of highly effective and selective anticancer agents remains a central challenge in oncological research. Herein, we report a systematic evaluation of the anticancer activity of a series of rhodium- and iridium-based NHC (N-heterocyclic carbene) complexes (complexes 1, 3, 5–7), including the novel complex 3, as well as two imidazole-containing complexes (2 and 4). Their cytotoxic profiles were investigated against B16-F10 melanoma cells and benchmarked against non-cancerous RAW 264.7 macrophage cells to assess cancer selectivity. Cytotoxicity of complexes 1–7 was quantified using the crystal violet assay following exposure to 0.01 mM and 0.1 mM concentrations over 24, 48, and 72 h. Half-maximal inhibitory concentrations (IC50) were determined to establish comparative selectivity and potency indices. Mechanistic insight was further obtained through morphological assessment of treated cells at IC50 values using polarised light optical differential interference contrast (PlasDIC) microscopy. At 0.1 mM, all complexes induced a pronounced reduction in B16-F10 cell viability, with complexes 2 and 3 emerging as the most potent, achieving >90% inhibition after 72 h. Notably, early time-point IC50 values (24 h) revealed marked cytotoxicity in melanoma cells (complex 2: 0.04 mM; complex 3: 0.05 mM), while eliciting minimal effects in RAW 264.7 macrophages, indicating selective anti-cancer activity. Morphological analysis of B16-F10 cells demonstrated features consistent with both apoptosis (membrane blebbing, apoptotic bodies, nuclear fragmentation) and necrosis (cell swelling, debris). Cell cycle analysis demonstrated a general increase in the S phase in B16-F10 cells, indicative of replication stress or cell cycle arrest, whereas no significant changes were observed in RAW 264.7 cells. Collectively, complexes 2, 3, and 5, display a compelling combination of potency and selectivity towards B16-F10 melanoma cells, with reduced cytotoxicity towards non-cancerous RAW 264.7 cells. These results support the continued development of NHC-based metal complexes as promising selective anticancer agents and warrant further mechanistic and in vivo investigation. HIGHLIGHTS • Range of Rh and Ir metal complexes tested against B16F10 melanoma cells and non-cancerous RAW 264.7 macrophage cells with moderate activity (0.04–0.09 mM IC50) and high selectivity. • Morphological analysis of B16-F10 cells revealed both apoptotic (membrane blebbing, apoptotic bodies, nuclear fragmentation) and necrotic (cell swelling, debris) features. • Cell cycle analysis showed a general increase in S phase in B16-F10 cells and showed no significant changes in RAW 264.7 cells.
The role of teaching experience in shaping university lecturers’ enacted TSPCK in electrochemistry
Rakhunwana, Langanani; Mundy, Christine Elizabeth; Mavhunga, Elizabeth (Taylor and Francis, 2026-04-13)
In higher education, lecturers shape learning through various teaching methods, which rely on pedagogical expertise, especially for difficult topics such as electrochemistry. Therefore, it becomes important to investigate whether pedagogical expertise develops with teaching experience and how that experience influences lecturers’ teaching practices. This study compared an experienced and a novice lecturer by analysing their teaching practices using the enacted topic-specific pedagogical content knowledge (enacted TSPCK) model. The study followed an exploratory qualitative case study design. Data were collected through lecture observations, audio-recordings of lectures and post-lecture interviews. The analysis involved deductive coding of lecture observations, audio-recordings and teaching materials to identify instances where two or more TSPCK components interacted; these instances were referred to as TSPCK episodes. Post-lecture interviews were then analysed to substantiate and contextualise the findings from the classroom data. The TSPCK episodes were classified into three categories reflecting increasing levels of advancement: simple, proficient and sophisticated. The experienced lecturer demonstrated a greater number of sophisticated TSPCK episodes, indicating more advanced enacted TSPCK. Interviews further revealed that the experienced lecturer’s use of representations, analogies and real-life examples was closely linked to teaching experience. An analysis of the frequency of occurrence of TSPCK components within the exhibited episodes for each lecturer was also conducted. Results revealed that the novice lecturer’s episodes showed a more even distribution of TSPCK components compared with the experienced lecturer. The implications of these findings are discussed, including the possible relationship between teaching experience and the quality of enacted TSPCK episodes overall.
Synthetic strategies for dihydrochalcones
Selepe, Mamoalosi A.; Madibana, Lorraine T.; Mthembu, Siyanda T.; Sonopo, Molahlehi S. (ARKAT USA, 2026)
Dihydrochalcones are open chain derivatives of flavanones characterised by the presence of the benzylacetophenone skeleton. They have been reported to exhibit many important biological activities, which make them attractive targets for chemical synthesis. Several synthetic strategies have been developed for the dihydrochalcones. The most widely employed synthetic method involves selective reduction of the double bonds of chalcones. Other methods that have been developed for the synthesis of dihydrochalcones include transition metal-catalysed coupling reactions as well as light-catalysed reactions. This review discusses the synthetic strategies for the dihydrochalcones.
Revisiting chemorganizers : supporting electrolysis learning in contemporary first-year chemistry classrooms
Rakhunwana, Langanani; Mundy, Christine Elizabeth (American Chemical Society, 2026-01-07)
Electrolysis remains one of the most conceptually difficult areas in chemistry. Despite the availability of modern technology and visualization tools, students continue to face challenges in connecting observable phenomena with underlying electrochemical concepts. Therefore, there is a need to revisit earlier developed tools and evaluate their usefulness in contemporary learning environments. This study revisits chemorganizers, instructional tools introduced in the early 2000s, and investigates their effectiveness in supporting student learning in electrolysis. Guided by Cognitive Load Theory, the study aimed to minimize extraneous cognitive load and promote deeper learning. A mixed-methods approach was adopted and implemented with two student cohorts (2023 and 2024) through a tutorial-based intervention. Both cohorts’ samples could be naturally divided into two groups due to the timing of the lectures: a well-prepared group (who experienced electrolysis lectures prior to engaging with the chemorganizers) and an under-prepared group (no prior exposure to electrolysis content in lectures). The intervention was centered on the use of chemorganizers. A tutorial worksheet and a content knowledge test, used as both pre- and post-tests, were included to support and assess the implementation. Statistical analysis showed significant performance improvement for both groups across both cohorts from the pre- to post-test. Furthermore, while the well-prepared group initially outperformed the under-prepared group in the pretest, the performance gap closed in the post-test. The chemorganizers may have closed the knowledge gap between the sample groups. An online survey was later distributed to capture student perceptions on the usefulness of the chemorganizers. Students reported that chemorganizers improved their understanding, supported problem-solving, and were easy to navigate. Critiques focused mainly on the implementation. Overall, the findings suggest that chemorganizers remain relevant and effective in supporting learning in topics within contemporary first-year chemistry classrooms.
Editorial for special issue "Coal fly ash as a resource : advances in characterization, utilization and sustainable solutions"
Doucet, Frédéric J. (MDPI, 2026-04-08)
Coal fly ash (CFA), the fine particulate by-product of coal combustion in thermal power plants, has traditionally been regarded as an environmental liability. Its large volumes, heterogeneous composition, and potential for trace metal release have posed persistent challenges related to disposal, land use, and long-term environmental management. Increasingly, however, this perception is shifting. Rather than being viewed solely as waste, CFA is now recognized as a secondary resource rich in reactive mineral phases and valuable elements suitable for industrial and environmental applications. This evolving perspective aligns closely with the principle of the circular economy, in which materials once destined for disposal are redirected into productive value chains, thereby reducing environmental burdens while conserving primary raw materials. Within this context, the present Special Issue was conceived to consolidate recent advances that deepen our understanding of CFA properties while showcasing innovative strategies for its beneficiation, functionalization, and utilization across diverse sectors. Emphasis has been placed on rigorous characterization, novel processing routes, and practical demonstrations of application pathways capable of transforming CFA into high-value products. Between 2024 and 2026, five contributions were assembled that collectively fulfill these objectives. Although differing in technical focus and application domain, all studies share a common theme: the systematic integration of detailed physicochemical and mineralogical characterization with targeted performance outcomes. Together, they demonstrate how fundamental understanding enables the rational and sustainable design of value-added uses for CFA.
Catena-poly [[bis [tris (4-methoxyphenyl) phosphine-κP] silver (I)] -μ-thiocyanato-κ2N:S]
Malan, F.P. (Frederick); Potgieter, Kariska; Meijboom, Reinout (International Union of Crystallography, 2025-09)
The coordination polymer, [Ag(NCS)(C21H21O3P)2]n or {[Ag(P(4-OMePh)3)2]-μ-NCS}n, features μ-thiocyanato ligands bridging between neighbouring silver(I) atoms, generating chains along the b-axis direction. Each AgI atom is four-coordinate, with two phosphorus donors from two distinct tris(p-methoxyphenyl)phosphine ligands, and two atoms from the thiocyanato ligands in severely distorted tetrahedral shape. The Ag—P [2.4331 (6) and 2.4625 (5) Å], Ag—N [2.339 (2) Å] and Ag—S [2.6760 (6) Å] bond lengths all appear within the expected ranges, with corresponding P—Ag—P and S—Ag—N angles of 129.610 (19) and 86.75 (6)°. In the crystal, the polymeric chains pack into layers parallel to (001) separated by the aryl groups of the phosphine ligands.
Bis [(2-methoxyphenyl) diphenylphosphane-κP] (nitrito-κ2O,O') silver (I)
Malan, F.P. (Frederick); Potgieter, Kariska; Meijboom, Reinout (International Union of Crystallography, 2025-03)
The synthesis and single-crystal structure description of a silver(I) diphenyl-2-methoxyphenylphosphine nitrite complex is described. The molecular structure of the title AgI complex, [Ag(NO2)(C19H17OP)2], is described, where a distorted tetrahedral coordination environment for the AgI atom is apparent within a O2P2 donor set as the nitrito anion coordinates in a bidentate mode. A fairly large angle for P—Ag—P [129.126 (16)°] is noted. The O—Ag—O chelate angle is = 50.38 (6)° and the P—Ag—O angles lie in the range 99.51 (5) to 118.45 (6)°. In the crystal, C—H⋯O interactions are evident.
(Nitrito-κ2O:O′)bis[tris(4-fluorophenyl)phosphine-κP]silver(I)
Malan, F.P. (Frederick); Potgieter, Kariska; Meijboom, Reinout (International Union of Crystallography, 2025-04)
The molecular structure of the title AgI complex, [Ag(NO2)(C18H12F3P)2], features a distorted tetrahedral geometry about the central AgI atom, with a total range of bond angles spanning from 49.80 (5) to 114.92 (1)°. The distortion arises primarily due to the small bite angle [49.80 (5)°] of the nitrito ligand. The compound crystallizes with one molecule in the asymmetric unit, in the space group P21/n, with Z = 4 and Z′ = 1.
Flavonol-mediated modulation of angiogenesis-related microRNAs in breast cancer : a narrative synthesis of current evidence and knowledge gaps
Ramali, Dakalo Portia; Maphoso, Tania Mmapule; Mulaudzi, Thanyani Victor; Ambele, Melvin Anyasi; Maharaj, Vinesh J.; Mabeta, Peaceful Lucy; Damane, Botle Precious (Taylor and Francis, 2026-05-08)
Angiogenesis is essential for breast cancer progression and metastasis; however, the clinical impact of vascular endothelial growth factor (VEGF)-targeted therapies remains limited due to adaptive resistance and activation of compensatory angiogenic pathways. Angiogenesis-regulating microRNAs (angiomiRs) act as upstream modulators of both VEGF-dependent and VEGF-independent signaling networks contributing to vascular plasticity, immune evasion, and therapeutic escape. Dietary flavonols such as kaempferol, myricetin, and quercetin have demonstrated anti-angiogenic activity in preclinical models, yet their mechanistic interaction with angiomiR-mediated regulation in breast cancer remains poorly characterized. This narrative review critically evaluates evidence identified through structured searches of Google Scholar, PubMed, Scopus, and Web of Science (2010–2026). We synthesize mechanistic and translational findings linking flavonols to microRNA-associated regulation of hypoxia signaling, endothelial activation, extracellular vesicle communication, and vascular normalization. Available evidence indicates that flavonols may influence angiogenic pathways both directly, by inhibiting key signaling cascades, and indirectly, through modulation of non-coding RNA networks. Despite these insights, experimental validation of specific flavonol-angiomiR interactions in breast cancer remains limited. AngiomiR modulation by flavonols, therefore, represents a mechanistically grounded but predominantly preclinical concept that warrants further translational investigation to clarify its therapeutic relevance and potential applications within precision oncology in breast cancer. PLAIN LANGUAGE SUMMARY : Blood vessels are essential for supplying breast cancer tumors with nutrients and oxygen. Tumors often rely on a molecule called vascular endothelial growth factor (VEGF) to form new blood vessels. For this reason, treatments that block VEGF have been developed to slow tumor growth. However, these treatments can lose effectiveness over time because cancer cells can find alternative ways to keep their blood supply. Blood vessel formation is controlled by signals within cells. MicroRNAs (miRNAs) are very small molecules that help turn genes on or off, influencing how blood vessels develop and how tumors respond to treatment. Flavonols are naturally occurring compounds found in certain fruits and vegetables. Some studies suggest that flavonols can affect blood vessel growth, possibly by influencing miRNAs involved in this process. Although early findings are promising, most evidence comes from laboratory and preclinical studies. Further research is needed to determine whether targeting these pathways could lead to safe and effective treatment strategies for patients with breast cancer.
Experimental and molecular-level insights into thermal conductivity of cobalt hydroxychloride nanofluids
Ntumba, P.T.; Khamlic, s.; Sone, Bertrand T.; Fester, V. (Elsevier, 2025-05-17)
Please read abstract in the article.
Structural and antimicrobial studies on a tricarbonyl rhenium(i) complex with the 6,7-dimethyl-2-(pyridin-2-yl)quinoxaline ligand
Sithole, Sibusiso A.; Mansour, Ahmed M.; Malan, F.P. (Frederick); Manikandan, Gurusamy; Katerere, David R.; Shehab, Ola R.; Manicum, Amanda-Lee E. (Royal Society of Chemistry, 2026-01-26)
A new tricarbonyl rhenium(I) complex featuring 6,7-dimethyl-2-(pyridin-2-yl)quinoxaline (1) was synthesized and characterized using spectroscopic and crystallographic techniques, supported by density functional theory (DFT) calculations. Ligand 1 acts as a bidentate N,N′-donor, coordinating through the pyridyl and quinoxaline nitrogen atoms to form a fac-[ReCl(CO)3(1)] (2) complex. Single-crystal X-ray diffraction analysis revealed an octahedral geometry around the Re(I) centre, with the three carbonyl ligands adopting a facial arrangement. Hirshfeld surface analysis indicated that weak C–H⋯Cl interactions play a significant role in crystal packing stabilization. DFT and time-dependent DFT (TDDFT) calculations confirmed the observed experimental geometry and provided insights into the metal–ligand bonding, charge distribution, and electronic transitions. The combined results highlight the structural and electronic features that contribute to the stability and potential bioactivity of this rhenium(I) tricarbonyl complex. The antimicrobial assay indicated that the rhenium metal complex (2) was superior to the ligand (1) in activity against six different microbial species, but inferior to the standard antimicrobial agents.
β-Lactam antibiotics and β-lactamases : historical perspectives and a review of β-lactamase inhibitors derived from natural products
Moyo, Phanankosi; Albert, Ikhane O.; Hlungwani, Neo; Sibanda, Thulani; Lumu, Perfoy; Khorommbi, Ndivhuwo Kevin; Kaur, Gurleen; Calvopina Tapia, Karina; Siegwart, George; Buabeng, Nana Kwaku; Danquah, Cynthia A.; McGaw, Lyndy Joy; Cosa, Sekelwa; Schofield, Christopher J.; Maharaj, Vinesh J. (Royal Society of Chemistry, 2026)
The history of β-lactam antibiotics and, subsequently, β-lactamase inhibitors highlight the indispensable role of natural products in modern medicine. The isolation and testing of β-lactam bearing natural products led to world-changing therapeutic breakthroughs, yielding efficacious, safe, and cost-effective medicines that are still widely used today. The scientific triumph of β-lactams was, however, followed by a period of reduced research into new antibiotics, during which time bacterial pathogens acquired multiple mechanisms of resistance. The available evidence suggests that this situation is not irretrievable – whereas insufficient medicinal chemistry is currently being carried out to enable a renaissance in antibiotic development, our molecular understanding of antimicrobial modes of action and resistance mechanisms has improved dramatically. The history of β-lactams and many other drug classes suggests that natural product-based approaches will be critical in the future. Here, we summarise the history of β-lactams, focusing on natural product science. We then examine historical and recent efforts to identify new types of β-lactamase inhibitors using natural product-based screening approaches. We conclude by providing a perspective on how we can most efficiently discover β-lactamase inhibitors from microbial and plant-derived natural products.
Synthesis and bioactivity studies of benzimidazole–chalcone hybrids
Makgoathana, Herman D.; Mthembu, Siyanda T.; Mhlanga, Thandi V.; Selepe, Mamoalosi A.; Sonopo, Molahlehi S. (MDPI, 2026-05)
Chalcones featuring α,β–unsaturated carbonyl group are associated with an extensive range of pharmacological properties. The synthesized derivatives of benzimidazole–chalcone are prominent classes of bioactive compounds that have demonstrated significant applications. Recently, there has been an encouraged demand for synthesizing aromatic N–heterocyclic α,β–unsaturated hybrids that comprise benzimidazole–chalcones, which could be evaluated for activities against several diseases. The current review presents the synthetic approaches of the recently prepared benzimidazole–chalcone compounds and their biological applications. The biological activity studies include cytotoxicity against several cancer cells, antibacterial, antifungal, antileishmanial, antimalarial, antiviral and antidiabetic activities. The in silico studies of hybridized benzimidazole–chalcones are also discussed. Therefore, the review shows the significance of benzimidazole–chalcone derivatives and their potential as effective bioactive agents.
Plant-derived modulators of tumor metabolism as novel, efficacious, and low-toxicity therapeutic agents for cancer treatment
Maphoso, Tania Mmapule; Ramali, Dakalo Portia; Mulaudzi, Thanyani Victor; Maharaj, Vinesh J.; Driver, Cathryn Helena Stanford; Damane, Botle Precious (MDPI, 2026-05)
Metabolic reprogramming is a core hallmark of malignancy, enabling tumor cells to sustain rapid proliferation, evade immune elimination, and develop resistance to therapy. Although a wide range of plant-derived phytochemicals exhibit anticancer activity with comparatively low toxicity, their capacity to disrupt specific metabolic dependencies exploited by tumors has not been comprehensively synthesized. This review brings together current mechanistic evidence showing how major phytochemical classes, including polyphenols, terpenes and terpenoids, glucosinolates, and alkaloids, interfere with pathways central to tumor metabolic fitness, such as aerobic glycolysis, pentose phosphate pathway flux, mitochondrial substrate oxidation, glutamine dependence, and redox homeostasis. It further introduces a pathway-focused framework that links phytochemical mechanisms to quantifiable metabolic outcomes and highlights their potential to remodel the tumor microenvironment by altering nutrient competition, oxidative stress responses, and hypoxia-driven signaling. Key barriers such as poor systemic bioavailability, rapid metabolic degradation, and limited tissue penetration are assessed alongside emerging formulation and delivery strategies designed to enhance therapeutic exposure while preserving low-toxicity profiles. Mapping these mechanistic insights onto clinical development needs allows prioritization of specific phytochemical-metabolic pathway pairs with the strongest potential for translation. This positions plant-derived metabolic disruptors as promising candidates for next-generation, low-toxicity anticancer therapies that strategically exploit defined metabolic vulnerabilities.
Neuroprotective and antioxidant properties of Polygala virgata fractions in a 6-hydroxydopamine-induced neurotoxicity model
De Beer, Andries Daniël; Rudolph, Wiehan; Maharaj, Vinesh J.; Steenkamp, Vanessa; Balmith, Marissa; Cordier, Werner (Elsevier, 2026-05)
INTRODUCTION : Ferroptosis contributes to Parkinson's disease progression given dysregulation of iron homeostasis and redox status. Polygala virgata is used ethnomedicinally for memory enhancement. This study assessed the cytoprotective and antioxidant properties of crude extracts and fractions of P. virgata using a 6-hydroxydopamine-induced (6-OHDA) SH-SY5Y neuroblastoma cytotoxicity model. METHOD : Dried roots of P. virgata (14% w/v) were sequentially extracted using dichloromethane/methanol (1:1) and methanol, which was combined to give a crude extract. The crude extract was separated into seven fractions using different ratios of water, acetonitrile and methanol on solid phase extraction (SPE). Inherent cytotoxicity of the samples (10 μg/mL), as well as their ability to reduce 6-OHDA-induced cytotoxicity (35 μM), was determined using the sulforhodamine B (SRB) assay after 48-h (h) exposure. The active fractions' cytoprotective effect in relation to reactive oxygen species (ROS), glutathione levels (GSH), lipid peroxidation, and mitochondrial integrity was determined fluorometrically. Cytoprotective fractions’ phytochemical constituency was elucidated using liquid chromatography high resolution mass-spectrometry (UPLC-HRMS). RESULTS : Fractions 3 to 7 increased cell density after exposure to 6-OHDA by 31.14%, 28.08%, 30.72%, 40.58% (p < 0.01) and 28.86%, respectively, with no inherent cytotoxicity observed. Fraction 4 reduced 6-OHDA-induced ROS generation (2.09-fold) and lipid peroxidation (0.28-fold). Non-significant increases in GSH were noted (1.34 to 19.25%), while all fractions hyperpolarised the mitochondrial membrane. Multi-hydroxylated xanthones, flavones and flavans were tentatively identified using UPLC-HRMS. CONCLUSION : P. virgata fractions reduced 6-OHDA-induced cytotoxicity via decreased oxidative stress and hyperpolarisation of the mitochondrial membrane, most likely ascribed to the identified xanthones, flavones and flavans. Isolation and purification of these compounds are warranted as potential antioxidant scaffolds. HIGHLIGHTS • First in vitro neuroprotective activity of Polygala virgata identified. • Little to no cytotoxicity present in fractions. • Neuroprotection linked to reactive oxygen species reduction (F4) and glutathione modulation (F6). • Possible synergism with identified compounds due to ratiometric differences.
Antimalarial polyethylene glycol-lumefantrine conjugates : synthesis and effect of linker chemistry on drug release
Govender, Thenesia R.; Matshe, William M.R.; Dube, Nokuthula; Cele, Zamani E.D.; Williams, Aurelia Alvina; Pilcher, Lynne A.; Balogun, Mohammed O. (Wiley, 2026-02-12)
Polymer–drug conjugates have seen limited exploration in antimalarial therapy, despite their successful development for cancer and other diseases. With rising resistance and a critical shortage of first-line treatments for severe malaria, innovative drug delivery strategies are urgently needed to maximize the currently available drugs. Building on our previous work that demonstrated a water-soluble polymer–lumefantrine conjugate for the intravenous treatment of severe malaria, we investigated the influence of linker chemistry on drug release rate and kinetics of a new polyethylene glycol-lumefantrine conjugate under conditions relevant to malaria pathophysiology. Four homologous aliphatic diacid linkers (succinic, glutaric, adipic, and dodecanedioic acids) containing4, 5, 6, and 12 carbon atoms, respectively, were introduced between the polymer and the drug. The conjugates were structurally well-defined and selectively cleaved at the ester bond under acidic conditions (pH 5.5), releasing only free lumefantrine, while remaining stable in human plasma (pH 7.4). Drug release rates were inversely proportional to linker length, with only the succinic acid-linked conjugate, which exhibited an initial burst release, deviating from first-order kinetic models. Complete inhibition of the Plasmodium falciparum NF54 strain was observed in vitro with a divalent variant of the succinic acid-linked conjugate, underscoring its potential for effective therapeutic action.
Synthesis and electrochemical investigation of ligand-tuned antimony sulphide nanoparticles for persulfate-driven photocatalysis
Ferjani, Hela; Fayemi, Omolola E.; Yusuf, Tunde Lewis; Sawunyama, Lawrence; Alhussain, Hanan; Onwudiwe, Damian C. (Elsevier, 2026-07)
Ligand engineering offers a powerful approach for tuning the physicochemical and electronic properties of semiconductor nanomaterials, thereby optimising their photocatalytic and electrochemical performance. In this study, antimony sulphide (Sb₂S₃) nanoparticles were rationally designed using three surface-capping ligands, oleic acid (OAc), oleylamine (OAm) and octadecylamine (ODA) yielding Sb₂S₃ (1), Sb₂S₃ (2), and Sb₂S₃ (3), respectively. Systematic characterisation confirmed the successful formation of highly crystalline orthorhombic-phase Sb₂S₃ with ligand-dependent modulation of morphology and optical properties. Electrochemical behaviour was evaluated using cyclic voltammetry of screen-printed carbon electrodes (SPEs) modified with the nanoparticles. Among the series, SPE–Sb₂S₃ (1) exhibited superior anodic and cathodic current responses with minimal peak-to-peak separation, indicative of enhanced charge-transfer kinetics facilitated by the oleic acid ligand environment. The photocatalytic activity was investigated for the degradation of Safranine-O (Safsingle bondO) dye. Sb₂S₃ (1), Sb₂S₃ (2), and Sb₂S₃ (3) achieved degradation efficiencies of 51%, 46%, and 48%, respectively. Synergistic coupling of Sb₂S₃ (1) with persulfate (Sb₂S₃ (1))+PS) markedly enhanced the degradation efficiency to 94%, which was further optimized to 99.7% under 0.3 g L−1 catalyst loading, 0.4 g L−1 persulfate concentration, and pH 2. Kinetic analysis revealed that the apparent rate constant (kₐₚₚ) of the Sb₂S₃ (1) + PS system was ∼3.2 times higher than that of pristine Sb₂S₃ (1), confirming the ligand-assisted activation of persulfate and accelerated radical-mediated oxidation. Overall, the results demonstrate that ligand engineering profoundly influences the electronic conductivity, surface reactivity, and catalytic efficiency of Sb₂S₃ nanoparticles. The Sb₂S₃ (1)+PS system thus represents a highly efficient and tunable platform for persulfate-driven photocatalysis, with significant potential for advanced wastewater treatment and environmental remediation. HIGHLIGHTS • Ligand engineering effectively tailored the properties of orthorhombic Sb₂S₃ nanoparticles. • Oleic-acid-capped Sb₂S₃ exhibited the best electrochemical performance on modified screen-printed electrodes. • Photo-degradation by the pristine Sb₂S₃ on Saf-O achieved efficiencies ranging from 46 to 51%. • Coupling of oleic-acid-capped Sb₂S₃ with persulfate (PS) boosted photocatalytic efficiency to 99.7%. • Ligand-assisted PS activation significantly enhanced the kinetics in Sb₂S₃ (1)+PS, enabling advanced wastewater treatment.

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