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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Now showing 1 - 20 of 657

Tungsten-based nano-architecture for the photocatalytic degradation of recalcitrant pharmaceutical pollutants : a review
(Elsevier, 2025-09) Adesibikan, Ademidun Adeola; Saliu, Oluwaseyi Oluwadamilare; Ndungu, Patrick Gathura; patrick.ndungu@up.ac.za
The growing occurrence of pharmaceutical contaminants in aquatic environments presents a significant challenge to water security, a critical component of sustainable development. These emerging pollutants, often resistant to conventional treatment methods, pose risks to human health and disrupt aquatic ecosystems, highlighting the urgent need for advanced water purification strategies. As a result, there is a need for the development of innovative and environmentally sustainable techniques and advanced oxidation processes (AOPs), including photocatalysis using tungsten-based nanomaterials (TBNPs), have shown a promising approach. This review critically focuses on the application of TBNPs as eco-effective photocatalysts, exploring the potential synergistic effects of combining tungsten (W) nanoparticles with other materials, leading to enhanced photocatalytic performance. It discusses the principal mechanism of photodegradation, focusing on the interaction between TBNPs and pharmaceutical pollutants. It also presents an overview of recyclability (>80 % degradation efficiency by the 5th cycle), advantages, and limitations. This review shows that TBNPs exhibit promising photocatalytic efficiency compared to other materials, based on reported studies. HIGHLIGHTS • Degradation of pharmaceuticals using W-based materials for was reviewed. • W-nanomaterials exhibit >60 % degradation efficiency for pharmaceuticals. • Maintained stability and structural integrity over 2–15 cycles • Performance stems from oxygen vacancies that boosts radical generation. • Superoxide radicals (O2−) dominate degradation over OH/h+ in W-systems.
Advancements in piezo-photocatalysts for sustainable hydrogen generation and pollutant degradation : a comprehensive overview of piezo-photocatalysis
(Elsevier, 2025-03) Masekela, Daniel; Balogun, Sheriff A.; Yusuf, Tunde Lewis; Makgato, Seshibe; Modibane, Kwena D.
Photocatalysis and piezocatalysis have been extensively employed in energy production and environmental restoration applications. However, the photocatalysis process suffers from rapid recombination of photogenerated electrons (e−) and holes (h+), limiting its practical application. Recently, the piezoelectric effect, which relies on the conversion of mechanical energy to trigger chemical reactions, has shown promise. It can produce an internal piezoelectric field under mechanical vibration, promoting the separation and migration of photogenerated charge carriers. This enhancement leads to significantly improved photocatalytic performance. However, there are still limited reports on other strategies to improve the performance of piezo-photocatalysts. Therefore, a comprehensive review was conducted to categorize the development of piezo-photocatalysts, detailing their classifications, synthetic methods and construction strategies, as well as their applications in energy production and wastewater treatment. This review aims to address the present challenges and future prospects of piezo-photocatalysis, providing clarity on its developmental trajectory. HIGHLIGHTS • Overview of classification and synthesis of piezo-photocatalyst, including hydrothermal and solvothermal methods. • Strategies for modifying piezo-photocatalys to improve catalytic perfomance. • Structural properties and bandgap engineering for improved charge separation. • Analysis of piezo-photocatalytic performance in hydrogen production and wastewater treatment. • Challenges and future directions for optimizing perfomance and scalability of piezo-photocatalyst.
Preparation of polydimethylsiloxane thin films containing immobilized CdSeTe/ZnS quantum dots for water sensing applications
(South African Chemical Institute, 2024-01) Putter, Wilme; Nsibande, Sifiso A.; Forbes, Patricia B.C.; patricia.forbes@up.ac.za
Pollutants in water systems are a significant environmental problem, as they can have harmful effects on both human health and the ecosystem. Here we developed a robust method for preparing CdSeTe/ZnS core/shell (C/S) quantum dots (QDs) immobilized into polydimethylsiloxane (PDMS) thin films for pollutant sensing applications. Highly fluorescent hydrophobic QDs were first synthesized using the hot-injection organometallic approach with the use of hydrophobic trioctylphosphine oxide and oleic acid ligands as capping agents. The C/S QDs had an average particle diameter of 4.0 nm and had broad absorbance in the ultraviolet-visible region. Their maximum fluorescence was at 594 nm and the photoluminescence quantum yield of the C/S QDs relative to rhodamine 6G was 47%. The C/S QDs were then immobilized into PDMS (to form QD@PDMS) by means of an optimized spin coating procedure onto glass slides at a speed of500 rpm and acceleration of 300 rpm/s for 10 s, followed by curing at 80 ºC for 15 min. This thin film format enabled direct use and analysis of the thin films by submersion into water samples followed by fluorescence spectroscopy. The homogeneity of the QD@PDMS thin films thus produced was excellent, as determined by visual inspection under an ultraviolet lamp and by fluorescence spectroscopy. An excitation wavelength of 400 nm led to the highest fluorescence intensity of the thin films and repeated exposure to this excitation wavelength did not have a major negative impact on the fluorescence emission of the QD@PDMS thin films, as the difference between the maximum and minimum fluorescence emission intensity was 8% over 60 repeated measurements. A mixture of water and ethanol (2:1) had the smallest effect on the fluorescence of the films and was thus the most effective matrix for sensing of organic pollutants. The interaction of the QD@PDMS films with individual organic pollutants (polar atrazine pesticide and non-polar phenanthrene) and with real water samples, resulted in a change in fluorescence of the thin films indicating that they are a promising candidate for sensing pollutants in water. The relative uptake and interaction of organic compounds by the thin films would need to be determined and their selectivity towards target analytes investigated for a particular application, in order to assess the viability of use of the QD@PDMS thin films to screen for the presence of the analytes and to semi-quantify them using fluorescence.
Dual charge transfer mechanisms in intimately bonded S-scheme heterojunction photocatalyst with expeditious activity toward environmental remediation
(Wiley, 2025-05) Mafa, Potlako J.; Malefane, Mope E.; Opoku, Francis; Oladipo, Adewale O.; Mamba, Gcina; Yusuf, Tunde Lewis; Nure, Jemal Fito; Lebelo, Sogolo L.; Liu, Dan; Gui, Jianzhou; Mamba, Bhekie B.; Kuvarega, Alex T.
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Pristine graphene oxide treatment of wastewater from a typical sub-tropical mine in Chegutu, Zimbabwe
(Springer, 2025) Kalitsilo, F.R.; Hashemi, H.; Mombeshora, Edwin Tonderai; et.mombeshora@up.ac.za
Mining activities in sub-tropical regions are one of the major contributors to environmental contamination and therefore require monitoring and mitigation methodologies. The study investigated the composition of the real-world wastewater from mine explosions and explored the potential of graphene oxide as an adsorbent. Heavy metals, namely, Fe (12.10 ppm), Cu (40.70 ppm), Cr (148 ppm) and Pb (0.03 ppm) were present. The optimal pH, adsorbent dose, temperature, and contact time for heavy metal removal were 12.08, 0.5 g, 25 °C and 0.5 h, respectively. The basic conditions were favourable for efficient removal through the adsorption method. Kinetic modelling indicated adsorption via pseudo-second-order kinetics, insinuating the influence of oxygen moieties of graphene oxide. Furthermore, the Langmuir isotherm revealed favourable removal of Fe, Cu, and Cr. The study indicated potential hazards of current mining activities, especially unmonitored illegal mines in sub-tropical regions. These findings highlight the prospects of graphene oxide as a practical and effective adsorbent for water resource recovery facilities. Therefore, the study demonstrated the capability to adopt pristine graphene oxide in a simple protocol using simple setups for wastewater recovery in the sub-tropical regions in a natural matrix.
Investigations into the impact of storage conditions and filtration on the analysis of natural organic matter in water
(South African Chemical Institute, 2025) Marais, Savia S.; Nokeri, Boitumelo K.; Forbes, Patricia B.C.; patricia.forbes@up.ac.za
When treating water for drinking water purposes, it is crucial to consider the composition of natural organic matter (NOM). NOM is a complex mixture of organic compounds influencing water quality and treatment processes. To ensure accurate reporting of analytical results, suitable sample storage and preparation are essential for maintaining sample integrity. This study investigated the effects of different storage conditions on water samples collected from Africa's largest bulk water provider, which sources its water from the Upper Vaal Catchment area. Samples were stored for varying durations under different temperature and light conditions to assess their impact on dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV254). The results showed that storing water samples for 34 days in the dark, at room temperature or at 5 oC did not significantly alter the DOC and UV254 measurements compared to the initial sample measurements. The pre-washing of filters from different brands with ultrapure water indicated that there were retained UV-active contaminants in the filter materials, of which 81% to 91% were removed after washing with 25 mL of ultrapure water. Furthermore, the portable, battery-operated UV254 Go! analyser is a cost-effective tool for direct field measurements of NOM aromaticity.
(1R,2S,4aR,6S,8R,8aS)-1-(3-Hydroxypropanoyl)- 1,3,6,8-tetramethyl-1,2,4a,5,6,7,8,8a-octahydronaphthalene- 2-carboxylic acid
(International Union of Crystallography, 2024) Botha, C.J. (Christoffel Jacobus); Fouche, Gerda; Malan, F.P. (Frederick); frikkie.malan@up.ac.za
The molecular structure of C18H28O4, (+)-diplodiatoxin, is described, whereby the absolute configuration of the structure of diplodiatoxin has been confirmed by single-crystal X-ray diffraction. Diplodiatoxin crystallizes in the chiral P43212 space group with one molecule in the asymmetric unit.
Enhanced photocatalytic efficiency of a novel GO/Bi2SO5/AgBr ternary heterojunction for the degradation of tetracycline and rhodamine B
(Elsevier, 2025-06) Oluwole, Adewunmi Olufemi; Yusuf, Tunde Lewis; Tichapondwa, Shepherd Masimba; Daramola, Michael Olawale; Iwarere, Samuel Ayodele; samuel.iwarere@up.ac.za
Please read abstract in the article.
Enhanced piezo-induced photocatalytic activity of BaTiO3/Cd0.5Zn0.5S S-scheme heterojunction for water pollution remediation : performance, degradation pathway, and toxicity evaluation
(Elsevier, 2025-06) Mohlala, Tshepo T.; Yusuf, Tunde Lewis; Masukume, Mike; Ojijo, Vincent; Mabuba, Nonhlangabezo
Please read abstract in the article.
Mesoporous Mn-substituted MnxZn1-xCo2O4 ternary spinel microspheres with enhanced electrochemical performance for supercapacitor applications
(Nature Research, 2024-05-19) Dolla, Tarekegn Heliso; Lawal, Isiaka Ayobamidele; Kifle , Gizachew Wendimu; Jikamo , Samuel Chufamo; Matthews , Thabo; Maxakato , Nobanathi Wendy; Liu , Xinying; Mathe , Mkhulu; Billing, David Gordon; Ndungu, Patrick Gathura
Extensive investigations have been carried out on spinel mixed transition metal oxide-based materials for high-performance electrochemical energy storage applications. In this study, mesoporous Mn-substituted MnxZn1−xCo2O4 (ZMC) ternary oxide microspheres (x = 0, 0.3, 0.5, 0.7, and 1) were fabricated as electrode materials for supercapacitors through a facile coprecipitation method. Electron microscopy analysis revealed the formation of microspheres comprising interconnected aggregates of nanoparticles. Furthermore, the substitution of Mn into ZnCo2O4 significantly improved the surface area of the synthesized samples. The electrochemical test results demonstrate that the ZMC3 oxide microspheres with an optimal Mn substitution exhibited enhanced performance, displaying the largest specific capacitance of 589.9 F g−1 at 1 A g−1. Additionally, the ZMC3 electrode maintained a capacitance retention of 92.1% after 1000 cycles and exhibited a significant rate capability at a current density of 10 A g−1. This improved performance can be ascribed to the synergistic effects of multiple metals resulting from Mn substitution, along with an increase in the surface area, which tailors the redox behavior of ZnCo2O4 (ZC) and facilitates charge transfer. These findings indicate that the incorporation of Mn into mixed transition metal oxides holds promise as an effective strategy for designing high-performance electrodes for energy storage applications.
Electrocapacitive removal of Na and Cd ions from contaminated aqueous solution using Fe3O4-poly (3,4-ethylenedioxythiophene) poly(styrene sulfonate) modified chitosan nanosheets
(Nature Research, 2024-11-15) Saliu, Oluwaseyi D.; Leping, Omphemetse; Yusuf, Tunde Lewis; Adeniyi, Adewale G.; Ramontja, James
Chitosan nanosheets (NS) stabilized on poly (3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) was functionalized using Fe3O4 to capacitively remove chloride ions and toxic cadmium ions at optimized pH, concentration, and number of charging cycles. The synthesis procedure was investigated by Fourier transform infrared spectroscopy (FTIR), X-Ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Scanning Electron Microscope – Energy Dispersive X-ray Spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller (BET). The analyses confirms increase in surface area of the nanocomposite from 41 to 132 m2/g and a decrease in crystallinity from 75.3 to 66.9% after nanosheet formation. The highest sorption exchange capacity (SEC) for this work, 93% CdCO3 removal is achieved at 100 CDI cycles while 82% NaCl removal was achieved at 80 cycles. The SEC% increased with pH during Na ion deionization and decreased with pH during Cd removal. The works shows that chitosan is able to impart advanced structural properties to Fe3O4 and PEDOT and is able to reduce reverse migration of ions from electrodes to bulk solution, leading to higher SEC performance.
Investigation of the antimycobacterial activity of African medicinal plants combined with chemometric analysis to identify potential leads
(Nature Research, 2024-06-25) Moyo, Phanankosi; Ofori, Michael; Bodede, Olusola S.; Wooding, Madelien; Khorommbi, Ndivhuwo Kevin; McGaw, Lyndy Joy; Danquah, Cynthia A.; Maharaj, Vinesh J.; vinesh.maharaj@up.ac.za
The emergence of drug-resistant Mycobacterium tuberculosis strains is a threat to global health necessitating the discovery of novel chemotherapeutic agents. Natural products drug discovery, which previously led to the discovery of rifamycins, is a valuable approach in this endeavor. Against this backdrop, we set out to investigate the in vitro antimycobacterial properties of medicinal plants from Ghana and South Africa, evaluating 36 extracts and their 252 corresponding solid phase extraction (SPE) generated fractions primarily against the non-pathogenic Mycobacterium smegmatis and Mycobacterium aurum species. The most potent fraction was further evaluated in vitro against infectious M. tuberculosis strain. Crinum asiaticum (bulb) (Amaryllidaceae) emerged as the most potent plant species with specific fractions showing exceptional, near equipotent activity against the non-pathogenic Mycobacterium species (0.39 µg/ml ≤ MIC ≤ 25 µg/ml) with one fraction being moderately active (MIC = 32.6 µg/ml) against M. tuberculosis. Metabolomic analysis led to the identification of eight compounds predicted to be active against M. smegmatis and M. aurum. In conclusion, from our comprehensive study, we generated data which provided an insight into the antimycobacterial properties of Ghanaian and South African plants. Future work will be focused on the isolation and evaluation of the compounds predicted to be active.
Synthesis of an 8-membered oxygen-containing benzo-fused heterocycle using flow technologies - an exercise in undertaking research with sustainability as a driver
(Royal Society of Chemistry, 2025-03) Currie, Bernice Mercia; Neyt-Galetti, Nicole C.; Olivier, Tanya; Van der Merwe, Petra; Dibokwane, Lerato Shirley; Reinhardt, Anshe Michelle; Van Wyk, Lorinda T.; Panayides, Jenny-Lee; Riley, Darren Lyall; darren.riley@up.ac.za
Due to their natural abundance and biological properties, benzo-fused heterocycles are attractive targets in the field of drug discovery. Previously, a synthetic strategy for accessing 5-, 6-, 7- and 8-membered oxygen-containing benzo-fused heterocycles with the oxygen atom in the less commonly encountered 2-position was reported, however, the approach was hindered by long reaction times and a reliance on high boiling point solvents such as DMF. Targeting an 8-membered analogue as an exemplar, we highlighted that the adoption of basic green chemistry principles coupled with the use of flow chemistry techniques could be utilised (with limited development time) to improve day-to-day sustainability when performing synthetic research. In the case in hand, several key improvements were noted including (i) a higher overall yield (37% vs. 26%), (ii) a significantly reduced reaction time (110 min vs. 136 h) and (iii) the avoidance of the undesirable solvent DMF.
The synthesis and investigation of novel 3-benzoylbenzofurans and pyrazole derivatives for anti-HIV activity
(Royal Society of Chemistry, 2025-05) Khuzwayo, Sinothile S.; Selepe, Mamoalosi A.; Meyer, Debra; Gama, Ntombenhle Hlengiwe
Please read abstract in the article.
Enhanced platinum and palladium recovery from aqueous solutions : a comparative study of acylthiourea and amine-modified silica gel adsorbents
(Royal Society of Chemistry, 2025) Mphahlele, Malehlogonolo R.R.; Mosai, Alseno Kagiso; Tutu, Hlanganani; Kotze, Izak A.
The recovery of precious metals from secondary sources is becoming increasingly important due to their natural scarcity and rising industrial demand. This study introduces a novel adsorbent, N-triethoxysilylpropyl-N′-benzoylthiourea-modified silica gel (TESP-BT-SG), developed for the selective recovery of platinum (Pt) and palladium (Pd) from aqueous solutions that simulate refinery wastewater. The extraction capabilities of TESP-BT-SG were compared with those of an amine-bearing adsorbent, (3-aminopropyl)triethoxy-silane-modified silica gel (APTES-SG), previously recognized for Pt and Pd recovery. Under optimal conditions, TESP-BT-SG achieved extraction efficiencies of 97% for Pt and 99% for Pd. Both adsorbents demonstrated rapid adsorption kinetics for Pd relative to Pt, reaching equilibrium within 3 hours for Pd and within 6 hours (TESP-BT-SG) and 24 hours (APTES-SG) for Pt. In solutions with elevated competing ion concentrations (5–100 mg L−1), both adsorbents retained high selectivity (>97%) for Pt and Pd. Adsorption isotherms and kinetic models were applied to elucidate the adsorption mechanisms, with the Langmuir isotherm and pseudo-second-order models providing the best fits, indicating monolayer coverage and chemisorption, respectively. Notably, the APTES-SG sorbent demonstrated enhanced performance with an increased loading capacity of 2.45 mmol g−1 compared to the previously reported 1.15 mmol g−1, achieved through our improved synthesis method. This modified APTES-SG showed significantly higher affinity for Pd (98%), Pt (97%), and iridium (Ir) (89%) compared to previous values of 8%, 33%, and 42%, respectively. The exceptional efficiency and selectivity of these silica-anchored adsorbents underscore their potential as cost-effective solutions for industries seeking to recover precious metals.
Green synthesis and enhanced photocatalytic performance of co-doped CuO nanoparticles for efficient degradation of synthetic dyes and water splitting
(Elsevier, 2025-01) Masekela, Daniel; Kganyakgo, Lovedonia K.; Modibane, Kwena D.; Yusuf, Tunde Lewis; Balogun, Sheriff A.; Seleka, Wilson M.; Makhado, Edwin
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Occurrence and distribution of selected pharmaceuticals in fresh fish along the Kenyan coast and assessment of potential human health risks
(Royal Society of Chemistry, 2025-06) Wanjeri, Veronica Wayayi Ogolla; Okuku, Eric; Ngila, Jane Catherine; Waiyaki, Edward; Nyingi, Joseph Kamau; Ndungu, Patrick Gathura; patrick.ndungu@up.ac.za
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Distribution of pharmaceuticals in marine surface sediment and macroalgae (ulvophyceae) around Mombasa peri-urban creeks and Gazi Bay, Kenya
(Springer, 2025-02) Wanjeri, Veronica Wayayi Ogolla; Okuku, Eric; Ngila, Jane Catherine; Ouma, Josephine; Ndungu, Patrick Gathura; patrick.ndungu@up.ac.za
Pollution in marine creeks has been increasing due to anthropogenic activities and has been a global concern. Limited research has been conducted on pharmaceuticals in marine sediment and macroalgae in African countries. In the present study, the levels of pharmaceuticals were assessed in surface sediment and different species of macroalgae (ulvophyceae; Cladophora sudanensis, Chaetomorpha crassa, Chaetomorpha indica, Enteromorpha kylinii, Ulva reticulate, Ulva lactuca and Cladophora sibugae) in Mombasa peri-urban creeks (Tudor, Makupa and Mtwapa creek) and Gazi bay during dry and wet seasons. The concentration of pharmaceuticals in the surface sediment during dry and wet seasons ranged between 0.04–686.8 ng/g and 0.01–2580.6 ng/g, respectively. The highest concentration of pharmaceuticals was observed in Tudor creek in dry and wet seasons, with a sum concentration of ∑1013 ng/g and ∑3111 ng/g, respectively. Gazi Bay was used as a reference environment for this study, and pharmaceuticals were detected in dry and wet seasons with a concentration of 0.10–686.8 ng/g and 0.18–93.5 ng/g, respectively. There was no seasonal variation in the pharmaceutical concentration during the dry and wet seasons. For macroalgae of ulvophyceae species, pharmaceutical concentration ranged below the detection limit (DL)–11059 ng/g. Compared to surface sediment, macroalgae showed a high concentration of pharmaceuticals in Tudor, Makupa and Mtwapa creeks. Tetracycline was higher in sediment and macroalgae in all the creeks than other pharmaceutical compounds. A high concentration of pharmaceuticals confirms sewage effluent into the marine environment of Mombasa peri-urban creek. Pharmaceuticals (acetaminophen, sulfamethoxazole, trimethoprim, carbamazepine and nevirapine) in sediment posed a medium (− 1 < Log10 RQ < 0) to higher risk (Log10 RQ > 0) to algae, invertebrates and fish in the dry and wet seasons. There is a need to sensitise the residents of coastal cities on the impact of sewage effluent into the marine environment and enact strict measures to limit the discharge of sewage effluents containing these contaminants into the marine environment. Nevertheless, it is recommended to conduct further research on the distribution of pharmaceuticals in the marine environment and the long-term combined impacts of these substances of these compounds on marine biota.
Antimalarial potential, LC-MS secondary metabolite profiling and computational studies of Zingiber officinale
(Taylor and Francis, 2024) Faloye, Kolade O.; Tripathi, Manish K.; Adesida, Stephen A.; Oguntimehin, Samuel A.; Oyetunde, Yemisi M.; Adewole, Adetola Henry; Ogunlowo, Ifeoluwa I.; Idowu, Esther A.; Olayemi, Uduak I.; Dosumu, Olamide D.
Malaria is among the top-ranked parasitic diseases that pose a threat to the existence of the human race. This study evaluated the antimalarial effect of the rhizome of Zingiber officinale in infected mice, performed secondary metabolite profiling and detailed computational antimalarial evaluation through molecular docking, molecular dynamics (MD) simulation and density functional theory methods. The antimalarial potential of Z. officinale was performed using the in vivo chemosuppressive model; secondary metabolite profiling was carried out using liquid chromatography–mass spectrometry (LC–MS). Molecular docking was performed with Autodock Vina while the MD simulation was performed with Schrodinger desmond suite for 100 ns and DFT calculations with B3LYP (6-31G) basis set. The extract showed 64% parasitaemia suppression, with a dose-dependent increase in activity up to 200 mg/kg. The chemical profiling of the extract tentatively identified eight phytochemicals. The molecular docking studies with plasmepsin II and Plasmodium falciparum dihydrofolate reductase-thymidylate synthase (PfDHFR-TS) identified gingerenone A as the hit molecule, and MMGBSA values corroborate the binding energies obtained. The electronic parameters of gingerenone A revealed its significant antimalarial potential. The antimalarial activity elicited by the extract of Z. officinale and the bioactive chemical constituent supports its usage in ethnomedicine.
In vitro nitric oxide inhibition of selected south African medicinal plants : a bio-guided purification of anti-inflammatory compounds from Conyza scabrida
(Elsevier, 2025-07) Rali, Sibusiso; Mshengu, Bongiwe P.; Van De Venter, Maryna; Maharaj, Vinesh J.
This study aimed to investigate the anti-inflammatory activity of plant species by in vitro screening of extracts, fractions, and pure compounds on LPS-activated RAW 246.7 mouse macrophages. Plants were sourced from the plant repository in the Biodiscovery Centre, at the University of Pretoria. The plant materials were ground into fine powdered and extracted with dichloromethane: methanol (DCM:MeOH) (1:1) followed by 100 % MeOH, filtered, concentrated, and dried to generate extracts. Twelve extracts were fractionated using positive pressure solid phase extraction (ppSPE) Gilson liquid hander workstation, resulting in seven fractions per plant extract. The observed anti-inflammatory activity was mainly attributed to specific ppSPE fractions of the plant extracts rather than the entire crude extract.The most active plants species identified with 90 % inhibition at 25 μg/mL, were Dodonaea. viscosa, Buxus natalensis, Flacourtia. indica, and Conyza scabrida. The crude extract and ppSPE fractions (6 and 7) of C. scabrida demonstrated strong anti-inflammatory activity at 50 μg/mL with 97.8 % and 97.0 % inhibition, respectively. The Ultra-Performance Liquid Chromatography coupled with Quadrupole Time-of-Flight Mass Spectrometry Mass Spectrometry (UPLC-QTOF-MS) analysis of the active ppSPE fractions was used to tentatively identify two major compounds 5,3′,4′-trihydroxy-3,6,7,8-tetramethoxyflavone (C1) and hautriwaic acid (C2) and were subsequently purified using preparative high-performance liquid chromatography (prep-HPLC-MS) and confirmed by Nuclear Magnetic Resonance (NMR). At a concentration of 100 μM, they inhibited NO production by 96.6 % and 59.2 %, respectively. We have provided scientific preliminary evidence supporting ethnopharmacological claims of twelve South African medicinal plant species traditionally used to treat inflammatory diseases.

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