Faculty of Sciences:biochimistry

ABSTRACT
Pig meat (Sus scrofa domesticus), because of its high yield and nutrient composition, particularly lipid, protein and minerals, is the world’s most produced and consumed meat. However, as most foods, it is consumed after cooking, which can impart positive or negative effects. So, the effects of two cooking methods (Boiling and Roasting) at various concentrations of spices on the lipids quality from an adult Large white pig meat (Longissimus dorsi muscle) were evaluated. The proximate composition showed a high level in Water (66.08%); Lipids (16.4%); Proteins (15.95%); and a low level in Ash (1.15%) and Carbohydrates (0.42%). It is also a good source of minerals such as Magnesium (147.28 g/kg), Sodium (2.88 g/kg), Phosphorus (1.42 g/kg) and Calcium (1.22 g/kg). All the treatments significantly (P < 0.05) increased the acid value of fat extracted on pig meat; however, the values obtained are in agreements with those recommended by the Codex Alimentarius. The treatments: Boiling + Allium sativum 5 g; Boiling + Zinziber officinale 3 g; Boiling + Allium cepa 3 g and Boiling + mixture, reduced the alteration of double bonds and the formation of hydroperoxydes. Except Boiling, all the treatments increased thiobarbituric acid reactive substances (TBARS) of pig meat compared to the control. Boiling especially with spices preserves the lipids quality of pig meat than Roasting.
Keywords: Pig meat, Cooking methods, Quality, Lipids, Spices.

Four freshwater fishes collected in Cameroon were used to determine the effect of culinary processes on their nutritional quality. They were cooked according to culinary processes common in Cameroonian households (frying, frying+boiling, boiling, roasting without seasoning and roasting with seasoning). The results showed significant decrease in protein content when the culinary treatments were compared to the control (raw fish). Indeed, a decrease in protein content (using dry matter) of about 39.03% after frying was observed whereas boiling limited the losses with a decrease of about 19.65% recorded. The lipid content of the fishes ranged from 4.57 to 8.02%, increased significantly (P < 0.05) after culinary treatments except in boiling. Samples had considerable minerals content for which calcium and phosphorus were the most abundant. A significant increase (P < 0.05) in the water absorption capacity was observed after roasting of Clarias gariepinus, Heterotis niloticus and Oreochromis niloticus (4.7 ± 0.21 ml/g). The oil absorption capacity of O. niloticus flours decreased significantly though it, was still higher than the threshold (0.7 and 0.9 ml/g) needed in food formulation. In general, these results suggests that frying reduced protein but increase lipid content, boiling was the best cooking treatment since little or no losses were observed in both macro and micro nutrients contents.

Aims: Utilization of phytobiotics as growth promoter in broilers rearing is not efficiently applied by farmers. This study aimed to assess the relationship between performance, carcass traits and lipid profile of broilers (Cobb 500 strain) fed with different rations supplemented with or without plant powders using principal component analysis. Methodology: One hundred broilers aged twenty-one day were randomly allocated to 5

The chelating ability of juglone and two of its derivatives towards Fe2+ion and the antioxidant activity (AOA) of the resulting chelates and complexes (in the presence of H2O and CH3OH as ligands) in gas phase is reported via bond dissociation enthalpy, ionization potential, proton dissociation enthalpy, proton affinity, and electron transfer enthalpy. The DFT/B3LYP level of theory associated with the 6-31+G(d,p) and 6-31G(d) Pople-style basis sets on the atoms of the ligands and the central Fe(II), respectively, was used. Negative chelation free energies obtained revealed that juglone derivatives possessing the O-H substituent (L2) have the greatest ability to chelate Fe2+ion. Apart from1B, thermodynamic descriptors of the AOA showed that the direct hydrogen atom transfer is the preferred mechanism of the studied molecules. NBO analysis showed that the Fe-ligand bonds are all formed through metal to ligand charge transfer. QTAIM studies revealed that among all the Fe-ligand bonds, ...

The sensitivity of pure and doped X 12 N 12 (X = B and Al) fullerene-like nano-cages (FLNs) toward the anti-cancer drug temozolomide (TMZ) is probed herein at DFT/M06-2X-D3/6-311G(d,p) theoretical level in both gas phase and water. A noticeable affinity of the FLNs toward TMZ was observed along with the negative gas-phase adsorption energies −1.37 and −2.09 eV for the most stable configurations of pure B 12 N 12 and Al 12 N 12 pristines, respectively. Considerable charge transfer from TMZ to the FLNs was also revealed via NBO analysis and the Hirshfeld atomic charges, making the dipole moment vector of the molecular complexes to be oriented from the nano-cages to the TMZ moiety. Furthermore, a percentage decrease in the HOMO-LUMO energy gap (Δ E g ) of 38.09 and 17.72% was obtained for the B 12 N 12 and Al 12 N 12 nano-cages, respectively. The percentage change in Δ E g was found to be reduced upon doping and solvation of the FLNs. Finally, a recovery time in vacuum ultraviolet ligh...

Herein is presented a density functional theory (DFT) study of reactivity and structural properties of transition metal complexes of the Schiff base ligand 2,2′(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene))bis(phenylmethan-1-yl-1-ylidene)dibenzoic acid (hereafter denoted EDA2BB) with Cu(II), Mn(II), Ni(II), and Co(II). The quantum theory of atoms-in-molecules (QTAIM), conceptual DFT, natural population analysis (NPA), and molecular electrostatic potential (MEP) methods have been used. Results have revealed a distorted octahedral geometry around the central metal ion in each gas phase complex. In the DMSO solvent, a general axial elongation of metal-oxygen bonds involving ancillary water ligands has been observed, suggestive of loosely bound water molecules to the central metal ion that may be acting as solvent molecules. Weak, medium, and strong intramolecular hydrogen bonds along with hydrogen-hydrogen and van der Waals interactions have been elucidated in the complexes investi...

The emergence of artemisinin-resistant variants of Plasmodium falciparum necessitates the urgent search for novel antimalarial drugs. In this regard, an in silico study to screen antimalarial drug candidates from a series of benzimidazolethiosemicarbazone hybrid molecules with interesting antiplasmodial properties and explore their falcipain-2 (FP2) inhibitory potentials has been undertaken herein. FP2 is a key cysteine protease that degrades hemoglobin in Plasmodium falciparum and is an important biomolecular target in the development of antimalarial drugs. Pharmacokinetic properties, ADMET profiles, MM/GBSA-based binding free energies, reaction mechanisms, and associated barrier heights have been investigated. DFT, molecular dynamics simulation, molecular docking, and ONIOM methods were used. From the results obtained, four 4 N-substituted derivatives of the hybrid molecule (E)-2-(1-(5-chloro-1H-benzo[d]imidazol-2-yl)ethylidene)hydrazine-1-carbothioamide (1A) denoted 1B, 1C, 1D, and 1E are drug-like and promising inhibitors of FP2, exhibiting remarkably small inhibitory constants (5.94 × 10-14 − 2.59 × 10-04 n M) and favorable binding free energies (−30.32 to −17.17 kcal/mol). Moreover, the ONIOM results have revealed that 1B and possibly 1C and 1D may act as covalent inhibitors of FP2. The rate-determining step of the thermodynamically favorable covalent binding mechanism occurs across a surmountable barrier height of 24.18 kcal/mol in water and 28.42 kcal/mol in diethyl ether. Our findings are useful for further experimental investigations on the antimalarial activities of the hybrid molecules studied.

Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transition metal complexes [Cu(AOYP)2(OH2)2] (A), [Ni(AOYP)2(OH2)2] (B) and [Zn-(AOYP)2(OH2)2] (C), have been studied theoretically by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. AOYP is the oxadiazole ligand 2-(5-amino-[1,3,4]-oxadiazol-2-yl)phenol. The geometries of these complexes were initially optimized using two basis sets: LAN2DZ and a generic basis set, the latter of which was selected for subsequent analysis. The stability of the complexes arising from intramolecular interactions and electron delocalization was estimated by natural bond orbital (NBO) analysis. The NBO results showed significant charge transfer from lone pair orbitals on the AOYP donor atoms O19, O21, N15 and N36 to central metal ions in the complexes, as well as to the benzene and oxadiazole rings. The electronic spectrum of (A) showed bands at 752 and 550 nm mainly attributable to ligand-tometal charge transfer (LMCT) transitions, and a band at 446 nm assigned to a d-d transition. The electronic spectrum of (B) consisted of bands at 540, 463 and 395 nm mainly due to d-d transitions. Calculated electronic bands for (C) occurred at 243, 238 and 235 nm, arising from intraligand charge transfer (ILCT) transitions within AOYP. A good agreement in terms of band positions was found between experimental and calculated absorption spectra of the complexes.

Recent studies have shown that 4-methoxyacetophenone thiosemicarbazone (MAPTSC) and its complexes with some transition metal chlorides are potent antimicrobial agents. To deepen the understanding of their structure-activity relationships necessary for rational drug design, their structural and spectral properties, along with thione-thiol tautomerism of MAPTSC, have been studied herein using the density functional theory (DFT). From our results, the thione tautomer of MAPTSC is more stable than the thiol counterpart in ethanolic solution, and thione-to-thiol tautomerization is highly precluded at ambient temperature (25°C) by a high barrier height ≈46.41 kcal/mol. MAPTSC can therefore exist as a mixture of the thione (major) and thiol (minor) tautomers in ethanolic solution at room and higher temperatures. Conformational analysis has revealed five possible conformers of the thione tautomer, of which two are stable enough to be isolated at 25°C. Based on our computed values of MAPTSC-...

Nonlinear optical (NLO) properties of organic and metal-organic materials are of considerable interest to emerging optoelectronic and photonic technologies. Much work has been carried out on the former materials but the latter ones have received less attention till date. Herein, a density functional theory (DFT) study on the combined effects of transition metal chelation and solvent polarity on the first hyperpolarizability (βtot) of 4-methoxyacetophenone thiosemicarbazone (MAPTSC) is reported. MAPTSC exhibits a tautomeric form with higher optical nonlinearity rendering its NLO response in polar solvents potentially switchable. Our results have revealed significant modifications of the first hyperpolarizability of MAPTSC upon complexation with different transition metal chlorides in the presence of solvents with varying dielectric constants. Therefore, its second-order NLO response is highly tunable by the synergy of transition metal chelation and solvent polarity. MAPTSC and its Zn...

The chelation ability of divalent Mg, Ca, Fe, Co, Ni, Cu, Zn, and monovalent Cu ions by neutral and anionic forms of juglone has been investigated at DFT/B3LYP/6-31+G(d,p) level of theory in gas and aqueous phases. It is noteworthy that only the 1 : 1 stoichiometry was considered herein. The effects of these metals on the radical scavenging activity of neutral juglone were evaluated via the usual descriptors of hydrogen atom transfer. According to our results, metal chelation by the two forms of juglone was spontaneous and exothermic in both media. Based on the binding energies, Cu(II) ion showed the highest affinity for the ligands. QTAIM analyses identified the metal-ligand bonds as intermediate type interactions in all the chelates, except those of Ca and Mg. It was also found that the chelates were better radical scavengers than the ligands. In the gas phase, the scavenging activity of the compounds was found to be governed by direct hydrogen atom transfer, the Co(II) chelate be...

Thiosemicarbazones (TSCs) possess significant antimalarial properties believed to be linked to the inhibition of major cysteine proteases, such as falcipain-2, in Plasmodium falciparum. However, the binding modes of TSCs to the active site of these enzymes are not clear. As a result of this, the nature of the bonding interactions between the active site of falcipain-2 and different derivatives of acetophenone thiosemicarbazone (APTSC) and propiophenone thiosemicarbazone (PPTSC) acting as inhibitors, have been studied herein via topological analyses of electron density. Derivatives of APTSC and PPTSC are well known to possess inhibitory effects against Plasmodium falciparum. Equilibrium geometries of the inhibitor–active site complexes in the aqueous phase have been obtained via dispersion-corrected density functional theory (DFT-D3) calculations. In-depth analyses of the covalent and noncovalent interactions in these complexes have been performed using the quantum theory of atoms in...

This work reports on the density functional theory (DFT) and its time-dependent extension (TD-DFT) study of the structural, electronic, and charge transport properties of 2-(5-mercapto-1,3,4-oxadiazol-2-yl) phenol (MODP) and some of its transition M2+ complexes (M = Fe, Co, Cu, Ni, Zn, Pd, Pt). Reorganization energy, integral charge transfer, mobility, open circuit voltage, and electronic properties of these compounds have been calculated by employing the global hybrid functional PBE0 in conjunction with the Karlsruhe basis set def2-TZVP. Results show that MODP and its transition metal complexes are good electron donors for organic solar cells (OSC) owing to their relatively higher HOMO and LUMO energies compared to the prototypical (6, 6)-phenyl-C61-butyric acid methyl ester (PCBM). Energy gaps ranging between 2.502 and 4.455 eV, energy driving forces (∆EL-L) ranging between 2.08 and 2.44 eV, and large open circuit voltages ( V OC ) ranging from 1.12 to 2.05 eV were obtained. The r...

The nonlinear optical (NLO) properties of ethyl 4-[( E )-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate (EMAB) and some of its derivatives are investigated herein using the density functional theory (DFT) and time-dependent (TD)-DFT methods. The density functionals B3LYP, CAM-B3LYP, M06-2X and ω B97XD, and basis sets 6-31 + G**, 6-311 + + G** and Def2-TZVPP have been used. From the results, EMAB and its substituted derivatives studied are promising candidates for NLO materials. In all cases, the static first and second hyperpolarizabilities (31.7–86.5 × 10 −30 and 84.4–273 × 10 −36 electrostatic units (esu), respectively) and the frequency-dependent NLO properties are found to be significantly larger (about 43–103 and 28–76 times greater) than those of the NLO prototypical molecule, para -nitroaniline. Furthermore, the maximum absorption wavelengths of the molecules fall within the UV region of the electromagnetic spectrum. Relative to EMAB, the derivatives have shown improved t...

This study reports the nonlinear optical (NLO) properties of the exohedral adsorption of N-(4-methoxybenzylidene) isonicotinohydrazone (INH) onto B12N12 and Al12N12 nanocages. All ground state computations were performed using the density functional theory (DFT) method at the B3LYP-D3/6-311G(d,p) level of theory in the gaseous phase. Excited state computations were achieved via the time-dependent density functional theory (TD-DFT) at the CAM-B3LYP/6-311G(d,p) level of theory. Molecular electrostatic potential (MEP) analysis of INH reveals the presence of three preferential interaction sites: the O-atom of carbonyl (site 1), the N-atom of pyridine (site 2), and the N-atom of the azomethine group (site 3). The highest interaction energy values for the adsorption of INH onto the B12N12 and Al12N12 were −43.560 and −52.724 kcal·mol−1, respectively, indicating a chemisorption process. The computed Gibbs free energy change (ΔGad) and adsorption enthalpy change (ΔHad) values for all comple...

Background: In response to the propagation of bacteria resistant to many antibiotics also called multi-drug
  resistant (MDR) bacteria, the discovery of new and more efficient antibacterial agents is primordial. The present
  study was aimed at evaluating the antibacterial activities of seven Cameroonian dietary plants (Adansonia digitata,
  Aframomum alboviolaceum, Aframomum polyanthum, Anonidium. mannii, Hibiscus sabdarifa, Ocimum gratissimum
  and Tamarindus indica).
  Methods: The phytochemical screening of the studied extracts was performed using described methods whilst the
  liquid broth micro dilution was used for all antimicrobial assays against 27 Gram-negative bacteria.

  Results: The results of the phytochemical tests indicate that all tested extracts contained phenols and triterpenes,
  other classes of chemicals being selectively present. The studied extracts displayed various degrees of antibacterial
  activities. The extracts of A. digitata, H. sabdarifa, A. polyanthum, A. alboviolaceum and O. gratissimum showed the
  best spectra of activity, their inhibitory effects being recorded against 81.48%, 66.66%, 62.96%, 55.55%, and 55.55%
  of the 27 tested bacteria respectively. The extract of A. polyanthum was very active against E. aerogenes EA294 with
  the lowest recorded minimal inhibitory concentration (MIC) of 32 μg/ml.

  Conclusion: The results of the present work provide useful baseline information for the potential use of the studied
  edible plants in the fight against both sensitive and MDR phenotypes.

  Keywords: Antibacterial, Multi-drug resistant bacteria, Dietary plants