Department of Chemistry- Journal Articles
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- ItemOpen AccessA Cytotoxic Indole Alkaloid from Alstonia boonei(Taylor & Francis publishing, 2016-11-24) Balogun, Olaoye; Ajayi, Olukayode Solomon; Agberotimi, JulianaStem bark of Alstonia boonie (1.24 kg) was exhaustively extracted with 95 % aqueous methanol. The crude extract was defatted with n-hexane and thereafter subjected to extensive chromatography to yield Alstiboonine (1) which was fully elucidated and characterised using 2D NMR analysis. Alstiboonine, crude extract and the n-hexane fraction were subjected to brine shrimps lethality test at varying concentrations. The result showed that all the test samples exhibited significant cytotoxicity.
- ItemOpen AccessPolyphenolic compounds with anti-tumour potential from Corchorus olitorius (L.) Tiliaceae, a Nigerian leaf vegetable(2016-06) Taiwo, Bamigboye; Taiwo, Grace O.; Olubiyi, Olujide Oludayo; Fatokun, Amos AkintayoChromatographic fractionation of the methanolic extract of Corchorus olitorious (L.) (Tiliaceae), on silica gel yielded two polyphenolic compounds. The structures of the compounds were elucidated as Methyl-1,4,5-tri-O-caffeoyl quinate and Trans-3-(4-Hydroxy- 3-methoxyphenyl) acrylic anhydride, based on extensive use of spectroscopic techniques such as 1H and 13C NMR, DEPT and 2D NMR experiments (COSY, HSQC, HMBC), IR and MS. To establish an initial proof-of-concept for the biological relevance of these compounds, their cytotoxicity in the HeLa cell line was assessed as an index of their anti-tumour potential. The compounds when tested at a range of concentrations up to 1.6 mM were found to possess mild cytotoxic activity. The trans-3-(4-hydroxy-3-methoxyl phenyl) acrylic anhydride was found to be related to curcumin, a compound known to have anti-cancer activity. The plant therefore represents a source of natural ‘lead’ compounds with anti-tumour potential
- ItemOpen AccessElectrochemical detection of Epinephrine using Polyaniline nanocomposite films doped with TiO 2 and RuO 2 Nanoparticles on Multi-walled Carbon Nanotube(Elsevier publisher, 2017-05-10) Tsele, Tebogo P.; Adekunle, Abolanle; Fayemi, Omolola E; Ebenso, EnoElectrochemical properties of functionalized MWCNT/polyaniline doped with metal oxide (TiO 2 , RuO 2 ) nanoparticles were explored. Successful synthesis of MWCNT, TiO 2, RuO 2 , PANI, MWCNT-PANI-TiO 2 , and MWCNT-PANI-RuO 2 nano materials were confirmed using suitable characterization techniques. Successful modification of gold (Au) electrode with these nanoparticles was confirmed using electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Au-MWCNT-PANI-TiO 2 and Au-MWCNT-PANI-RuO 2 gave the best electron transport properties towards the oxidation of epinephrine (EP) compared with other electrodes investigated. The Tafel values 0.448 and 0.442 V/decade for Au-MWCNT-PANI-TiO 2 and Au-MWCNT-PANI-RuO 2 electrodes respectively in (EP) suggest adsorption due to analyte oxidation intermediates products. The linear calibration plot was obtained for EP at concentrations range 4.9 to 76.9 m M. The limits of detection of EP were estimated to be 0.16 and 0.18 m M for Au-MWCNT-PANI-TiO 2 and Au-MWCNT-PANI-RuO 2 electrodes respectively. The interference study using DPV showed clear peak separation for amino acid (AA) and EP. Therefore, the modified electrodes can selectively detect epinephrine without interference from ascorbic acid signal. The analytical performance of the fabricated sensors has been evaluated for detection of epinephrine (EP) in a pharmaceutical sample with satisfactory results
- ItemOpen AccessHigh level leaching of heavy metals from colorful ceramic foodwares: a potential risk to human(Springer publishing, 2017-06-05) Aderemi, Taiwo Adedoyin; Adenuga, Adeniyi Abiodun; Oyekunle, John Adekunle Oyedele; Ogunfowokan, Aderemi OkunolaAbstract Ceramic foodwares are among the products used by people on daily basis without being cautious of exposures to heavy metals through possible leaching from the glaze ce- ramics. This study investigated the levels of heavy metals foundinsomecommonlyusedceramicfoodwaresin Nigeria with the aim of determining levels of human expo- sures through the use of the ceramics. To achieve this, acid digestion was carried out for the total metal concentrations and leaching tests were done using 4% acetic acid as a leaching agent. Metal concentrations were quantified using flame atomic absorption spectrometry (FAAS) and particle-induced X-ray emission spectrometry (PIXES) analysis. All the ceram- ic foodwares studied were found to contain varied amounts of heavy metals in their glazes, with concentrations in the range of 26.45–2071.46, 5.20–547.00, 1.24–2681.02, 2590.00– 8848.40, 6.42–654.66, 112.69–649.95, 63.38–2518.51, and 3786.51–8249.44 μgg −1 for Pb, Cd, Zn, As, Cu, Cr, Mn, and Fe, respectively. Concentrations of the metals leached from the ceramics were in the range of 0.11–0.97, 0.01– 0.28, 0.00–4.19, 1.93–15.00, 0.01–0.41, 0.09–0.60, 0.01– 2.14, and 0.01–11.53 mgL −1 for Pb, Cd, Zn, As, Cu, Cr, Mn, and Fe, respectively. Comparing the ratio of the metals leached from the ceramic wares with those of the metal oxides in the ceramics, it was noticeable that not all the metals de- tected in the ceramic samples were domiciled in the glaze but in the clay materials used for the ceramics.
- ItemOpen AccessIdentification and comparison of the volatile constituents of fresh and dried leaves of Spondias mombin found in North-central Nigeria: in vitro evaluation of their cytotoxic and antioxidant activities(Taylor & Francis publishing, 2016-05-09) Oladimeji, Abdulkabir Oladele; Aliyu, Medinat Bola; Ogundajo, Akintayo Lanre; Babatunde, Oluwatoyin; Adeniran, Oluremi Ishola; Balogun, Olaoye SolomonContext: Various studies have shown that the leaf extracts of Spondias mombin Linn (Anacardiaceae) possess pharmacological properties such as antioxidant and antiviral effects. However, no biological activity from its essential oil has been reported in literature. Objective: To analyse the chemical constituents, cytotoxic activity and antioxidant capability of the essential oils from fresh and dried leaves of S. mombin. Materials and methods: Hydrodistillation using Clevenger-type apparatus was employed to obtain the essential oil. Oil analysis was performed using an HP 6890 Gas Chromatograph coupled with an HP 5973 Mass Selective Detector. The cytotoxicity bioassay was carried out using the brine shrimp lethality test (10,000-0.01 μg/mL). Additionally, the reactive oxygen species scavenging potential of the two S. mombin oils (1000-200 μg/mL) were investigated using a hydroxyl radical scavenging and ferric iron reducing system. Results: Chemical analysis of essential oils from S. mombin revealed the presence of 41 compounds, with predominance of monoterpenoids, sesquiterpenoids and non-terpenoids derivatives. In both fractions, the principal component was β-caryophellene (27.9-30.9%), followed by γ-cadinene (9.7-12.3%). There was an increase in the oxygenated monoterpenoid contents and a concomitant decrease in the amounts of sesquiterpenoids hydrocarbons observed on drying the leaves. The oil obtained from the fresh leaves was more active than that obtained from dried leaves, with LC50 values (from the brine shrimp lethality assay) of 0.01 and 4.78 μg/mL, respectively. The two oils (from fresh and dried leaves) at 1.0 mg/mL scavenged hydroxyl radical by 83% and 99.8%, respectively. Moreover, they reduced ferric ion significantly and compared favourably with vitamin C. Conclusions: Essential oil derived from the leaves of S. mombin could hold promise for future application in the treatment of cancer-related diseases.