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Emmanuel Iwuoha     University Educator/Researcher 
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Emmanuel Iwuoha published an article in April 2019.
Top co-authors See all
Malcolm R Smyth

89 shared publications

School of Chemical Sciences

Věra Cimrová

81 shared publications

Institute of Macromolecular Chemistry

Omotayo A. Arotiba

67 shared publications

Department of Applied Chemistry, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa.

Jeanine L Marnewick

47 shared publications

Oxidative Stress Research Centre, Faculty of Health and Wellness Sciences, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, Symphony Road, Bellville 7535, South Africa;(F.R.);(J.M.)

Leslie F. Petrik

46 shared publications

Department of Chemistry, Environmental and Nano Sciences Research Group, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa

Publication Record
Distribution of Articles published per year 
(2003 - 2018)
Total number of journals
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Publications See all
Article 0 Reads 0 Citations Investigation of In-Vitro Antioxidant and Electrochemical Activities of Isolated Compounds from Salvia chamelaeagnea P.J... Ninon G.E.R. Etsassala, Adewale O. Adeloye, Ali El-Halawany,... Published: 12 April 2019
Antioxidants, doi: 10.3390/antiox8040098
DOI See at publisher website ABS Show/hide abstract
We have investigated the in-vitro antioxidant activity and electrochemical redox properties of a number of natural compounds (carnosol, carnosic acid, 7-ethoxyrosmanol, ursolic acid, rosmanol and ladanein) isolated from the methanolic extract of Salvia chamelaeagnea collected from the Cape floristic region, South Africa. The results from trolox equivalent antioxidant capacity (TEAC), ferric-ion reducing antioxidant parameter (FRAP) oxygen radical absorbance capacity (ORAC), as well as the inhibition of Fe2+-induced lipid peroxidation showed strong antioxidant capacities for carnosol and rosmanol. A structural analysis of the compounds suggests that multiple OH substitution, conjugation and lactone ring in carnosol and rosmanol are important determinants of the free radical scavenging activity and electrochemical behavior. Pharmacophore generated demonstrates H-donor/acceptor capabilities of the most active compounds. Rosmanol, when compared to other compounds, exhibits the lowest oxidation potential value with an anodic peak potential (Epa) value of 0.11 V, indicating that rosmanol has the highest antioxidant power, which is in good agreement with ORAC and lipid peroxidation experiments. The lipophilic nature of carnosol, carnosic acid and rosmanol enhanced their absorption and activity against oxidative stress related to the treatment of age-related diseases. These results confirm the first report on the in-vitro antioxidant and electrochemical activities of S. chamelaeagnea constituents and underline the medicinal uses of this plant as natural preservatives for skin ageing or in pharmaceutical applications.
Article 0 Reads 0 Citations Impedimetric sensor for tyramine based on gold nanoparticle doped-poly(8-anilino-1-naphthalene sulphonic acid) modified ... Wanderson Da Silva, Mariana Emilia Ghica, Rachel F. Ajayi, E... Published: 01 April 2019
Talanta, doi: 10.1016/j.talanta.2018.11.054
DOI See at publisher website
Article 0 Reads 0 Citations Copper(II) phthalocyanine/metal organic framework electrocatalyst for hydrogen evolution reaction application Gobeng R. Monama, Kwena D. Modibane, Kabelo E. Ramohlola, Ke... Published: 01 March 2019
International Journal of Hydrogen Energy, doi: 10.1016/j.ijhydene.2019.02.052
DOI See at publisher website
Article 0 Reads 0 Citations Electrochemical Screening and Evaluation of Lamiaceae Plant Species from South Africa with Potential Tyrosinase Activity Ninon G.E.R. Etsassala, Tesfaye Waryo, Olugbenga K. Popoola,... Published: 28 February 2019
Sensors, doi: 10.3390/s19051035
DOI See at publisher website PubMed View at PubMed ABS Show/hide abstract
South Africa is a country with a wide variety of plants that may contain excellent anti-tyrosinase inhibitors. With wide applications in cosmetics, pharmaceuticals and food products, tyrosinase inhibitors have received very special attention in the recent past as a way of preventing the overproduction of melanin in epidermal layers which often over time brings detrimental effects on human skin. In this present study, a fast screening method using a cyclic voltammetry technique was applied in the evaluation of methanolic extracts of twenty-five species of plants from the Lamiaceae family for anti-tyrosinase activity. Among these plants, those that showed a fast current inhibition rate at a minimum concentration when compared to a kojic acid standard were classified as having the greatest anti-tyrosinase activity. These include Salvia chamelaeagnea, S. dolomitica, Plectranthus ecklonii, P. namaensis, and P. zuluensis. The results presented herein focused in particular on providng firsthand information for further extensive research and exploration of natural product materials with anti-tyrosinase activity from South African flora for use in cosmetics, skin care and medicinal treatments.
Article 1 Read 0 Citations Graphene Oxide Decorated Nanometal-Poly(Anilino-Dodecylbenzene Sulfonic Acid) for Application in High Performance Superc... Nomxolisi R. Dywili, Afroditi Ntziouni, Chinwe Ikpo, Miranda... Published: 11 February 2019
Micromachines, doi: 10.3390/mi10020115
DOI See at publisher website PubMed View at PubMed ABS Show/hide abstract
Graphene oxide (GO) decorated with silver (Ag), copper (Cu) or platinum (Pt) nanoparticles that are anchored on dodecylbenzene sulfonic acid (DBSA)-doped polyaniline (PANI) were prepared by a simple one-step method and applied as novel materials for high performance supercapacitors. High-resolution transmission electron microscopy (HRTEM) and high-resolution scanning electron microscopy (HRSEM) analyses revealed that a metal-decorated polymer matrix is embedded within the GO sheet. This caused the M/DBSA–PANI (M = Ag, Cu or Pt) particles to adsorb on the surface of the GO sheets, appearing as aggregated dark regions in the HRSEM images. The Fourier transform infrared (FTIR) spectroscopy studies revealed that GO was successfully produced and decorated with Ag, Cu or Pt nanoparticles anchored on DBSA–PANI. This was confirmed by the appearance of the GO signature epoxy C–O vibration band at 1040 cm−1 (which decreased upon the introduction of metal nanoparticle) and the PANI characteristic N–H stretching vibration band at 3144 cm−1 present only in the GO/M/DBSA–PANI systems. The composites were tested for their suitability as supercapacitor materials; and specific capacitance values of 206.4, 192.8 and 227.2 F·g−1 were determined for GO/Ag/DBSA–PANI, GO/Cu/DBSA–PANI and GO/Pt/DBSA–PANI, respectively. The GO/Pt/DBSA–PANI electrode exhibited the best specific capacitance value of the three electrodes and also had twice the specific capacitance value reported for Graphene/MnO2//ACN (113.5 F·g−1). This makes GO/Pt/DBSA–PANI a very promising organic supercapacitor material.
Article 1 Read 1 Citation Spectroscopic and Voltammetric Analysis of Platinum Group Metals in Road Dust and Roadside Soil Charlton Van Der Horst, Bongiwe Silwana, Emmanuel Iwuoha, Ve... Published: 02 November 2018
Environments, doi: 10.3390/environments5110120
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The emission of toxic compounds by increasing anthropogenic activities affects human health and the environment. Heavy road traffic and mining activities are the major anthropogenic activities contributing to the presence of metals in the environment. The release of palladium (Pd), platinum (Pt), and rhodium (Rh) into the environment increases the levels of contamination in soils, road sediments, airborne particles, and plants. These Pd, Pt, and Rh in road dusts can be soluble and enter aquatic environment posing a risk to environment and human health. The aim of this study is to determine the levels of Pd, Pt, and Rh with spectroscopy and voltammetric methods. Potential interferences by other metal ions (Na(I), Fe(III), Ni(II), Co(II)) in voltammetric methods have also been investigated in this study. At all the sampling sites very low concentrations of Pd, Pt, and Rh were found at levels that range from 0.48 ± 0.05 to 5.44 ± 0.11 ng/g (dry weight (d.wt)) for Pd(II), with 17.28 ± 3.12 to 81.44 ± 3.07 pg/g (d.wt) for Pt(II), and 14.34 ± 3.08 to 53.35 ± 4.07 pg/g (d.wt) for Rh(III). The instrumental limit of detection for Pd, Pt, and Rh for Inductively Coupled Plasma Quadrupole-based Mass Spectrometry (ICP-QMS) analysis was found to be 3 × 10−6 µg/g, 3 × 10−6 µg/g and 1 × 10−6 µg/g, respectively. In the case of voltammetric analysis the instrumental limit of detection for Pd(II), Pt(II), and Rh(III) for differential pulse adsorptive stripping voltammetry was found to be 7 × 10−8 µg/g, 6 × 10−8 µg/g, and 2 × 10−7 µg/g, respectively. For the sensor application, good precision was obtained due to consistently reproduced the measurements with a reproducibility of 6.31% for Pt(II), 7.58% for Pd(II), and 5.37% for Rh(III) (n = 10). The reproducibility for ICP-QMS analysis were 1.58% for Pd(II), 1.12% for Pt(II), and 1.37% for Rh(III) (n = 5). In the case of repeatability for differential pulse adsorptive stripping voltammetry (DPAdSV) and ICP-QMS, good standard deviations of 0.01 for Pd(II); 0.02 for Pt(II), 0.009 for Rh(III) and 0.011 for Pd, 0.019 for Pt and 0.013 for Rh, respectively.