Oguejiofo T Ujam

A Schiff base, 4-hydroxy-6-methyl-3-[(1E)-1-(2-phenylhydrazinylidene)ethyl]-2H-pyran-2-one, is synthesized and characterized by ¹H and ¹³C NMR, IR spectroscopy, ESI-mass spectrometry and single crystal X-ray diffraction analysis. There are three crystallographically independent molecules in the asymmetric unit, space group C2/c, a = 30.011(2) Å, b = 17.601(2) Å, c = 13.6878(13) Å, β = 92.532(4)°, and Z = 24. The final reliable index is 0.0406 for 5997 reflections. The molecules are linked through intermolecular N–H…O hydrogen bonds into three-linked molecules forming a supramolecular ring.

N-(2-chloroethyl)morpholine-4-carboxamide (NCMC), N-(2-chloroethyl)tiomorpholine-4-carboxamide (NCTC) and N,N-bis(2-chloroethyl)piperazine-1,4-dicarboxamide (NCPD) were studied as corrosion inhibitors for mild steel using atomic absorption spectroscopy (AAS) and gravimetry and thermometry. Results obtained from the three techniques are similar and reveal that the compounds inhibit mild steel corrosion. The inhibition efficien-cies increased from 35.6% to 74.9% (NCMC), 44.5% to 82.4% (NCPD) and 52.6% to 90.1% (NCTC) at 30 °C when the inhibitor concentrations increased from 10 μM to 50 μM. The maximum inhibition efficiency values (at 50 μM) decreased to 46.6%, 58.1% and 61.2% for NCMC, NCPD and NCTC respectively, when the temperature was raised to 50 °C. The decrease in inhibition efficiency with increase in temperature suggested predominant physisorption mechanism in metal/inhibitor interactions. The formation of protective films of NCMC, NCPD and NCTC molecules on mild steel surface were confirmed by FTIR and XRD. The order of inhibitive strengths of the molecules is NCTC N NCPD N NCMC. Quantum chemical calculations revealed the prospective sites through which the molecules can interact with mild steel surface and some quantum chemically derived parameters were used to corroborate experimental.

Human African trypanosomiasis, also known as sleeping sickness, is caused by the single-celled kinetoplastid parasite Trypanosoma brucei transmitted to humans by infected tsetse flies. The disease threatens millions of people. Currently available treatment options are faced with
some important challenges. In this work, a total of eightyseven (87) morpholine derivatives were evaluated for druglikeness based on Lipinski’s rule of five and their ability to inhibit the activities of trypanosomal triosephosphate isomerase was assessed by molecular docking and calculation of free energy of binding. Analysis of the results revealed that 97.7% of the dataset complied with Lipinski’s criteria for a molecule to be orally bioavailable. Also, 50.0% of the studied compounds had a good total polar surface area profile, a parameter which is of great importance for the treatment of stage two Trypanosoma infections. Docking studies showed that all the dataset demonstrated affinity for triosephosphate isomerase. Moreover, six morpholines scored higher than the co-crystallized inhibitor of triosephosphate isomerase (2-phosphoglycerate). These derivatives
inhibited the activity of triosephosphate isomerase by making significant interactions with Glu 167, Val 214, 233, Asn 11, Lys 13, Ser 213, Leu 232, Ile 172, Gly 211, 212, 234, 235 and His 92 in the active site of the protein. Furthermore, besides the acceptable pharmacokinetic profiles of the six morpholines, they also showed inhibitory potencies toward four other validated antitrypanosomal drug targets. In view of the foregoing findings, we propose that the six morpholine derivatives be given worthwhile attention to develop them into novel trypanocides.

The Antibiogram properties of 1-chloro-2-isocyanatoethane derivatives of thiomorpholine (CTC), piperazine (CPC) and morpholine (CMC) were evaluated by the approved agar well diffusion, the minimum inhibitory concentration (MIC) and in silico techniques. A total of fourteen microbial cultures consisting of ten bacteria and four yeast strains were used in the biological study while affinity of the compounds for DNA gyrase, a validated antibacterial drug target, was investigated by docking method. Results indicate that both thiomorpholine and piperazine had zero activity against the Gram negative organisms tested. With morpholine, similar result was obtained except that cultures of Escherichia coli (ATCC 15442) and Salmonella typhi (ATCC 6539) presented with weak sensitivity (7–8 mm) as shown by the inhibition zone diameter (IZD) measurement. The Gram positive organisms were more sensitive to morpholine than the other compounds. The highest IZD values of 15–18 mm were achieved except for Streptococcus pneumoniae (ATCC 49619) in which mobility of the compound stopped after 12 mm. S. pneumoniae was resistant to both thiomorpholine and piper-azine. The yeast strains were not sensitive to any of the studied compounds investigated. The MIC tests evaluated against a reference antibiotic show that while morpholine was most active at 4 μg.ml-1 against both B. cereus ATCC (14579) and B. subtilis, the least active compound was thiomorpholine which inhibited S. aureus (ATCC 25923) at 64 μg.ml-1. The three compounds demonstrated high affinity for the target protein (DNA gyrase) ranging from-4.63 to-5.64 Kcal/mol and even showed better ligand efficiencies than three known antibiotics; chlorobiocin, ciprofloxacin and tetracycline. This study identified the studied compounds as potential antibiotic leads with acceptable physicochemical properties and gave the molecular basis for the observed interactions between the compounds and the target protein which can be harnessed in structural optimization process.

The reactivity of the metalloligand [Pt2(μ-S)2(PPh3)4] with the boron-functionalized alkylating agents BrCH2(C6H4)B(OR)2 (R = H or C(CH3)2) was investigated by electrospray ionization mass spectrometry (ESI-MS) in real time using pressurized sample infusion (PSI). The macroscopic reaction of [Pt2(μ-S)2(PPh3)4] with one mole equivalent of alkylating agents BrCH2(C6H4)B{OC(CH3)2}2 and BrCH2(C6H4)B(OH)2 gave the dinuclear monocationic μ-sulfide thiolate complexes [Pt2(μ-S){μ-SCH2(C6H4)B{OC(CH3)2}2}(PPh3)4]+ and [Pt2(μ-S){μ-S+CH2(C6H4)B(OH)(O–)}(PPh3)4]. The products were isolated as the [PF6]– salt and zwitterion, respectively, and fully characterized by ESI-MS, IR, 1H and 31P NMR spectroscopy and single crystal X-ray structure determinations.

The concentrations of heavy metals in rice grains and soils from Ada cultivated fields were investigated. Rice and soil samples were digested and the heavy metal concentrations determined using atomic absorption spectrophotometer. The results showed concentrations of metals (mg/kg) as follows: soil: Pb (4.64±2.18), Cd (0.83±0.83), Zn (20.26±18.60), Mn (68.90±19.91), Ni (3.46±2.42) and Cr (21.41±14.6); rice: Pb (3.99±1.43), Cd (1.10±0.53), Zn (65.37±58.09), Mn (37.81±5.82), Ni (3.12±1.49) and Cr (10.87±6.47). The Canadian, Nigerian and Chinese maximum allowable concentration for cadmium in soil were exceeded by 15%, 30% and 85% of the soil samples respectively. Heavy metals in all the rice samples evaluated were found to be above the World Health Organization (WHO) maximum permissible limit for lead, cadmium and chromium. Strong positive and significant correlations were observed between some metal pairs in soil and rice indicating similarity in origin. The estimated daily intakes of Pb and Cd from rice grown on the fields were higher than the safety levels established by WHO and JECFA respectively. Hazard Quotients and Total Hazard Index for Pb and Cd were greater than 1. This indicates that consumption of rice from these fields will likely induce adverse health effects arising largely from Pb and Cd exposure.

ABSTRACT The immobilisation of the dinuclear platinum(II) sulfido complex [Pt2(μ-S)2(PPh3)4] on solid supports has been investigated. Reaction with haloalkyl functionalised polymers [Merrifield's resin (chloromethylated polystyrene), chloropropyl silica, chloropropyl controlled pore glass and bromopropyl polysiloxane] gives complexes immobilised through alkylation of one of the sulfide ligands, forming a μ-thiolate ligand acting as an anchor to the polymer support, akin to well-established reactions of [Pt2(μ-S)2(PPh3)4] with molecular alkylating agents. The model complex [Pt2(μ-S)(μ-SCH2SiMe3)(PPh3)4]PF6 was prepared as the first molecular silicon-containing derivative of [Pt2(μ-S)2(PPh3)4], and was fully characterised by NMR spectroscopy, ESI mass spectrometry and single-crystal X-ray diffraction. Immobilisation of [Pt2(μ-S)2(PPh3)4] by phosphine exchange reactions was also achieved using commercial polystyrene-grafted triphenylphosphine, or a new immobilised phosphine [derived by sequential functionalisation of Merrifield's resin with a polyether amine and then Ph2PCH2OH].

The kinetics of oxidation of trioxosulfate(IV) ion SO32- by [(Fe(salen))2adi], was investigated in aqueous perchloric acid medium. Stoichiometric results indicate that one mole [(Fe(salen))2adi] was reduced per two moles SO32- oxidized. Under pseudo-first order conditions of SO32- being above 20-fold excess of concentration of the oxidant observed rates were invariant with respect to increase in concentration. Pseudo-first order rate constants were within (1.68 ± 0.003) x 103 s-1 implying zeroth order dependence of rate on [SO32-] and first order dependence on concentration of the oxidant. The rate of reaction increased with increase in [H+], was unaffected by change in ionic strength and decreased with increase in dielectric constant of the reaction medium. Addition of small amounts of AcO- and Mg2+ ions did not catalyze the reaction. A least squares fit of rate against [H+] was linear (r2 = 0.986) and with intercept indicating that oxidation of SO32- followed two parallel paths. The reaction was analyzed on the basis of a proton-coupled outer-sphere electron transfer mechanism.

The kinetics and mechanism of the reduction of the μ-adi-di[N,N′-bis{salicylideneethylenediaminatoiron(III)}] complex, [Fe2adi], by dithionate ion, S2O6 2−, have been investigated in aqueous perchloric acid at 29 °C, I = 0.05 mol dm−3 (NaClO4) and [H+] = 5.0 × 10−3 mol dm−3. Spectrophotometric titrations indicated that one mole of the reductant was oxidized per mole of oxidant. Kinetic profiles indicated first-order rate with respect to [Fe2adi] but zeroth-order dependence on [S2O6 2−]. The rate of reaction increased with increase in [H+], decreased with increased dielectric constant, but was invariant to changes in ionic strength of the medium. Addition of small amounts of AcO− and Mg2+ ions did not catalyse the reaction. A least-squares fit of rate against [H+]2 was linear (r 2 = 0.984) without intercept. The reaction was analysed on the basis of a proton-coupled outer-sphere electron transfer mechanism.

The immobilisation of the dinuclear platinum(II) sulfido complex [Pt2(μ-S)2(PPh3)4] on solid supports has been investigated. Reaction with haloalkyl functionalised polymers [Merrifield's resin (chloromethylated polystyrene), chloropropyl silica, chloropropyl controlled pore glass and bromopropyl polysiloxane] gives complexes immobilised through alkylation of one of the sulfide ligands, forming a μ-thiolate ligand acting as an anchor to the polymer support, akin to well-established reactions of [Pt2(μ-S)2(PPh3)4] with molecular alkylating agents. The model complex [Pt2(μ-S)(μ-SCH2SiMe3)(PPh3)4]PF6 was prepared as the first molecular silicon-containing derivative of [Pt2(μ-S)2(PPh3)4], and was fully characterised by NMR spectroscopy, ESI mass spectrometry and single-crystal X-ray diffraction. Immobilisation of [Pt2(μ-S)2(PPh3)4] by phosphine exchange reactions was also achieved using commercial polystyrene-grafted triphenylphosphine, or a new immobilised phosphine [derived by sequential functionalisation of Merrifield's resin with a polyether amine and then Ph2PCH2OH].

The Cd, As, Pb, Cr and Se contents of fillets of ten fish species and As, Cd and Pb contents of some parts of cow and goat meats were determined by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), after wet digestion of powdered samples with 1:1 HNO ,/H O . The ranges obtained 3 2 2 for the metals analyzed in fish (mg/kg, dry weight) are as follows; As (0.02-4.58), Se (0.66-1.66), Pb (0.45- 4.78), Cd (0.22-2.02) and Cr (0.18-1.96). While the ranges obtained for the metals analyzed in cow meat (mg/kg, dry weight) are as follows: As (0.82-2.09), Cd (0.28-1.50) and Pb (0.80-1.42) and the range of metals analyzed in goat meat are as follows: As (0.02-4.88), Cd (0.04-0.93) and Pb (0.02-1.36). Of all the samples analyzed, the goat intestine contained the highest amount of As (4.88±0.015). Mean Pb concentrations (mg/kg) in Hydrocynus forskahlii (3.51±0.06), Clarias anguillaris (3.43±0.021), Scomber japonicus (4.61±0.043) and Scomber scombrus (4.78±0.045) exceeded the recommended limits specified by most food regulatory bodies. It is concluded that fish samples in the study area have heavy metal accumulations
a little above recommended safety standards.