Browsing by Author "Oyetunde, Temidayo"

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    a-Amylase Inhibition, Anti-glycation Property and Characterization of the Binding Interaction of Citric Acid with a-Amylase Using Multiple Spectroscopic, Kinetics and Molecular Docking Approaches
    (Elsevier, 2022-07-15) Oyetunde, Temidayo
    The quest to suppress complications associated with diabetes mellitus is ever increasing, while food additives and preservatives are currently being considered to play additional roles besides their uses in food enhancement and preservation. In the present study, the protective prowess of a common food preservative (citric acid, CA) against advanced glycation end-products (AGEs) formation and its binding interaction mechanism with a-amylase (AMY), an enzyme linked with hyperglycemia management, were examined. Enzyme inhibition kinetics, intrinsic fluorescence, synchronous and 3D fluorescence spectroscopies, ultraviolet–visible (UV–Vis) absorption spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, thermodynamics, and molecular docking analyses were employed. Results obtained showed that citric acid decreased a-amylase activity via mixed inhibition (IC50 = 5.01 ± 0.87 mM, Kic = 2.42 mM, Kiu = 160.34 mM) and suppressed AGEs formation (IC50 = 0.795 ± 0.001 mM). The intrinsic fluorescence of free a-amylase was quenched via static mechanism with high bimolecular quenching constant (Kq) and binding constant (Ka) values. Analysis of thermodynamic properties revealed that AMY-CA complex was spontaneously formed (DG < 0), entropy driven (TDS > DH), with involvement of electrostatic forces. UV–Vis, FT-IR and 3D fluorescence spectroscopies affirmed alterations in aamylase native conformation due to CA binding interaction. CA interacted with His-101, Asp-197, His- 299, and Glu-233 within AMY active site. Our findings indicated that CA could impair formation of AGEs and interact with a-amylase to slow down starch hydrolysis; vital properties in management of type 2 diabetes complications.
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    Aerosol-assisted CVD of cadmium diselenoimidodiphosphinate and formation of a newiPr2N2P3 + ion supported by combined DFT and mass spectrometric studies
    (Royal Society of Chemistry (RSC), 2016-10-25) Oyetunde, Temidayo
    Aerosol-assisted chemical vapour deposition (AACVD) of Cd[(SePiPr2)2N]2 is shown to deposit cadmium selenide and/or cadmium phosphide on glass substrates, depending upon the growth conditions. The phase, structure, morphology and composition of the films were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The XRD indicated a hexagonal phase for cadmium selenide, whilst cadmium phosphide was monoclinic. Pyrolysis gas chromatography-mass spectrometry and density functional theory were used to deduce a breakdown mechanism for the deposition that favoured the formation of a new aromatic iPr2N2P3+ ion.
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    Cadmium Sulfide and Cadmium Phosphide Thin Films from a Single Cadmium Compound
    (American Chemical Society (ACS), 2011-02-10) Oyetunde, Temidayo
    Aerosol-assisted chemical vapor deposition of Cd[(SPiPr2)2N]2 leads to the growth of cadmium sulfide and/or phosphide thin films on glass. Decomposition of the precursor has been studied by pyrolysis-gas chromatography/ mass spectrometry and modeled by density functional theory.
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    The deposition of cadmium selenide and cadmium phosphide thin films from cadmium thioselenoimidodiphosphinate by AACVD and the formation of an aromatic species†
    (Royal Society of Chemistry (RSC), 2019-01-10) Oyetunde, Temidayo
    Aerosol-assisted chemical vapour deposition (AACVD) of Cd[(SPiPr2)(SePiPr2)N]2 yields hexagonal cadmium selenide and monoclinic cadmium phosphide films on glass substrates between 475 and 525 °C at different argon flow rates. The films were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy (XPS). All the results of XRD, EDAX and XPS are in agreement with our previous investigations on Cd[(SePiPr2)2N]2. A breakdown mechanism is proposed based on mass spectra and density functional theory calculations. A large peak at m/z 207 in the mass spectra, previously assigned by us as a new aromatic species, is also observed for this complex.
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    Exploring the Binding Interactions of Structurally Diverse dichalcogenoimidodiphosphinate Ligands with α-amylase: Spectroscopic Approach Coupled with Molecular Docking
    (Elsevier, 2020-10-15) Oyetunde, Temidayo
    Postprandial hyperglycemia has orchestrated untimely death among diabetic patients over the decades and regulation of α-amylase activity is now becoming a promising management option for type 2 diabetes. The present study investigated the binding interactions of three structurally diverse dichalcogenoimidodiphosphinate ligands with α-amylase to ascertain the affinity of the ligands for α-amylase using spectroscopic and molecular docking methods. The ligands were characterized using 1H and 31P NMR spectroscopy and CHN analysis. Diselenoimidodiphosphinate ligand (DY300), dithioimidodiphosphinate ligand (DY301), and thioselenoimidodiphosphinate ligand (DY302) quenched the intrinsic fluorescence intensity of α-amylase via a static quenching mechanism with bimolecular quenching constant (Kq) values in the order of x1011 M-1s-1, indicating formation of enzyme-ligand complexes. A binding stoichiometry of n≈1 was observed for α-amylase, with high binding constants (Ka). α-Amylase inhibition was as follow: Acarbose > DY301>DY300>DY302. Values of thermodynamic parameters obtained at temperatures investigated (298, 304 and 310 K) revealed spontaneous complex formation (ΔG<0) between the ligands and α-amylase; the main driving forces were hydrophobic interactions (with DY300, DY301, except DY302). UV–visible spectroscopy and F¨orster resonance energy transfer (FRET) affirmed change in enzyme conformation and binding occurrence. Molecular docking revealed ligands interaction with α-amylase via some key catalytic site amino acid residues (Asp197, Glu233 and Asp300). DY301 perhaps showed highest α-amylase inhibition (IC50, 268.11 ± 0.74 μM) due to its moderately high affinity and composition of two sulphide bonds unlike the others. This study might provide theoretical basis for development of novel α-amylase inhibitors from dichalcogenoimidodiphosphinate ligands for management of postprandial hyperglycemia.
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    Ferromagnetic FeSe2 from a Mixed Sulphur-selenium Complex of Iron [Fe {(SePPh2NPPh2S)2N}3] through Pyrolysis
    (Elsevier, 2020-04-06) Oyetunde, Temidayo
    Iron (III) thioselenoimidodiphosphinate complex, Fe{(SePPh2NPPh2S)2N}3], was synthesized from the ligand [Ph2P(S)HNP(Se)Ph2], and the complex employed as the combined source of the targeted elements (Fe and Se) to generate orthorhombic FeSe2. This was achieved by thermolysis using a quartz glass tube, under reduced pressure at 500 C during 1 h 30 min. The crystalline product was revealed by X-ray diffraction (XRD), while the morphology consisted of polygonal crystallites according to the scanning electron microscopy (SEM) studies. Superconducting quantum interference device (SQUID) measurements on the material confirmed its ferromagnetism as observed from the magnetization curve, indicated by the field-cooled and zero field-cooled conditions under a magnetic field of 100 Oe. This ferromagnetic material, FeSe2 finds useful application in producing electrical semiconductors.
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    Focus on Glucose: A World of Sugar
    (Green Chemistry Network, 2008-03-23) Oyetunde, Temidayo
    Exploring the diverse possibilities from sugar as a biomolecular platform
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    Phenyl Substituted ditelluro-imidodiphosphinate complexes of iron, nickel, palladium and platinum, and their pyrolysis Studies Generating metal tellurides
    (Elsevier, 2019-01-10) Oyetunde, Temidayo
    The tellurium complexes M[N(PPh2Te)2]n (M = Fe (1), Ni (2), Pd (3), Pt (4) and n = 2 or 3) have been prepared using the ditellurido anions [N(PPh2Te)2] and their ability to generate tellurides was investigated by pyrolysis in a quartz glass tube, under vacuum at 500 C for 90 min. The products were characterised by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of Xrays (EDAX) and X-ray photoelectron spectroscopy (XPS). The XRD revealed an orthorhombic phase for the metal telluride from 1, while the hexagonal phase was observed for tellurides from 2, 3 and 4 respectively. Magnetic measurements on FeTe2 (from 1) indicated an antiferromagnetic sample with a transition temperature at 75 K.
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    Precursor Engineering for the Synthesis of Mixed Anionic Metal (Cu, Mn) Chalcogenide Nanomaterials via Solvent-Less Synthesis
    (American Chemical Society (ACS), 2022-04-18) Oyetunde, Temidayo
    Metal−organic ligands with mixed chalcogenides are potential compounds for the preparation of mixed anionic metal chalcogenide alloys. However, only a few of such ligands are known, and their complexes are not well explored. We have prepared homo- and heterodichalcogenoimidodiphosphinate [(EE′PiPr2NH)] (E, E′ = Se, Se; S, S; S, Se) complexes of manganese and copper through metathetical reactions. The X-ray single crystal structure of [Mn{(SePiPr2)2N}2] 1 revealed a triclinic crystal system, with a MnSe4 core unit, whereas the crystal structure determination of [Mn{(SPiPr2)(SePiPr2)N}2] 2 indicated a triclinic crystal system with a Mn(S/Se)2 unit. Both metal centers are tetrahedral, with two deprotonated bidentate ligands forming the coordination sphere. The free ligand was found to exhibit a gauche configuration in the solid state. The energies of the various rotamers of dithio-analogue were studied by DFT calculations. The decomposition behavior of complexes with homo- and heterochalcogenides was investigated, and the complexes were employed as single-source precursors to generate manganese and copper chalcogenides through solvent-less melt reactions between 500 and 550 °C. The deposited powders were characterized by powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), and elemental mapping. MnS, MnSe2, and MnSSe phases were obtained from the decomposition of respective manganese complexes. In contrast, the decomposition of copper-based complexes yielded Cu2−xSe and the sulfur-doped Cu3Se2 phase from seleno- and mixed thio/selenocomplexes of Cu, respectively. The morphology ranged from random sheet-like structures to agglomerated platelets, while the selected area electron diffraction (SAED) revealed the crystalline nature of the materials. Depending on the nature of the complex and the temperature, different amounts of phosphorus were present as an impurity in the synthesized products.
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    Synthesis, Characterisation and Antimirobial Studies of Metal(II) Complexes of Trimethoprim and 2,2' Bipyridine Heterocycle
    (Nigerian Research Journal of Chemical Sciences, 2021-06-14) Oyetunde, Temidayo
    Mixed-ligand complexes of trimethoprim (TMP) with 2,2′-bipyridine (bipy) with the formular [M(TMP)(bipy)X].nH2O, where M = Mn(II), Co(II), Ni(II), Cu(II), Fe(II), Zn(II) and X= Cl/SO4, were synthesized and characterized by percentage metal, infrared, electronic spectroscopies, room temperature magnetic moments, melting points, conductance measurements and elemental analysis. From the infrared spectral data, TMP behaves as a bidentate ligand bonding to the metals via the N atom of the pyrimidine amino group (3412-3300 cm-1) and nitrogen atom of the azomethine moiety (1666-1639 cm-1) while the bipy coordinated through the diimine nitrogen atoms (1593-1404 cm-1). The room temperature magnetic moment and electronic spectra indicated that the metal(II) complexes were monomeric and octahedral. The molar conductance of the synthesised complexes in the range 24-40 Ω-1cm2 mol-1 confirmed their non-electrolytic and covalent nature. The antimicrobial studies showed that the complexes were inactive towards the tested fungus but possessed good antibacterial activities. The observed trend for the antibacterial activities demonstrated by the mixed metal complexes was in the order Mn >Zn > Cu > Fe > Co ~ Ni thus making [Mn(TMP)(bipy)Cl2].2H2O the most biologically active among them. It was also observed that antibacterial activities exhibited varied directly with concentration as the highest activities were observed at the highest concentration of 40 mg/mL.