Advanced Journal of Chemistry, Section A
Volume:5 Issue: 2, Spring 2022

In this case study, the major mechanisms contributing to failure of a petrochemical firewater (FW) pipeline were assessed. The outer surface of FW pipe exhibited general corrosion and formation of noticeable pits due to separation of wrapping coating. The results of XRF, EDS, and XRD analysis demonstrated the presence of Fe2O3, CaCO3, SiO2, and NaCl indicating the presence of iron oxide (Fe2O3) and silica (SiO2) as corrosion products, and CaCO3 and NaCl as sediments found in water. The formation of deposits (precipitates) on the whole internal surface of the pipe and occurrence of general corrosion, under-deposit corrosion, and tuberculation was confirmed by visual inspection and microscopic examination (SEM). The deposits formed in the pipe may originate and/or accelerate corrosion through forming oxygen depleted area under deposit, playing as anodic region compared to the surrounding area and lead to more aggressive corrosive attack under the deposit. Moreover, the tubercles were the main reason of formation of oxygen concentration cells as the oxygen-deficient sites beneath the tubercles playing as anodic regions and surrounding areas act as cathodic regions resulting in localized corrosion.

2-methoxy-2-hydroxychalcone (2M2HC) and 4-methoxy-2,4-dichlorochalcone (4M24DC) and their metal complexes were synthesized, characterised and confirmed by melting point determination, Fourier transform infrared (FT-IR), UV-Visible, 1H-NMR, EI-MS and AAS spectroscopic techniques. Elemental analysis was carried out and found in agreement with the calculated values. Metal(II) complexes, [M(L1-2)2], [where M = Ni(II), Cu(II), Co(II); L=2-methoxy-2-hydroxychalcone (2M2HC) and 4-methoxy-2,4-dichlorochalcone (4M24DC)] were subsequently prepared. The biological evaluation of the synthesized chalcone derivatives and the metal complexes were carried out. The chalcones and their metal complexes were screened for antioxidant (DPPH; 2,2-diphenyl-1-picrylhydrazyl and ABTS; 2,2-azino-bis(3-alkylbenzothiazoline-6-sulphonic acid) and antimicrobial activities. Overall, the ligands (chalcones) and their metal complexes demonstrated good to moderate antioxidant and antimicrobial activities.

The use of plant products as medicines could be traced as far back as the beginning of human civilization. The medicinal plant “Strychnos innocua (a Loganiaceae plant)” is a deciduous shrub growing 2-12 m tall. This study aimed at using GC-MS to determine the chemical composition and antifungal activity of a root bark methanol extract against Candida krusei. The plant sample was collected and identified at Ahmadu Bello University, Zaria. The maceration extraction method was used to obtain the methanol root bark extract. The chromatogram from the GC-MS analysis revealed sixty-four (64) peaks corresponding to fifty-five phytoconstituents from various organic groups. Among the significant compounds discovered are 9,12-Octadecadienoic acid (5.48%), Benzofuran, 6-ethenyl-4,5,6,7-tetrahydro-3,6-dimethyl-5-isopropenyl-, trans- (6.72%), Tetradecanoic acid, 12-methyl-, methyl ester (6.87%), Ethyl Oleate (8.29%), 1,2-Benzenedicarboxylic acid, butyl 8-methylnonyl ester (9.10%), Linoleic acid ethyl ester (10.31%) with 6-Octadecenoic acid, methyl ester and peak area of 11.42% being considered the highest peak area. In contrast, Bicyclo[13.1.0]hexadecan-2-one with a peak of 0.03% is considered the lowest peak area. It can be concluded that the phytocompounds discovered in the root bark methanol extract of Strychnos innocua could be valuable in treating some human ailments.

This study aimed at designing highly potent dengue virus (DENV) inhibitors targeting the NS2B-NS3 protease from 1,2-benzisothiazol-3(2H)-one-1,3,4-oxadiazole (BTZO) hybrid through quantitative-structure-activity relationship (QSAR) and subsequently structure-based design, molecular docking, and ADMET (Adsorption-Distribution-Metabolism-Excretion Toxicity) of the designed BTZO derivatives. A QSAR model was developed to correlate the biological activity with the descriptor calculated from the BTZO hybrid using multiple linear regression. The model was validated and the information from the model was used to design more potent derivatives which were evaluated through molecular docking and ADMET prediction. The QSAR model showed good statistical quality (R2Training = 0.89228, R2predicted = 0.72734 R2adjusted = 0.87074, Q2LOO = 0.81896, and cR2p = 0.8154) leading to the design of nine active BTZO derivatives with better inhibitory activity than the lead compound (7n). A binding score of -23.731, -20.210, -23.568 kcal/mol better than Panduratin and Ribavirin (-14.1715, -17.2571 kcal/mol) for compounds C-148, C-205, and C-206 respectively were obtained, including good ADMET properties. This discovery not only aided in understanding the binding manner of BTZO hybrid to the NS2B-N3 targets but also provided information for the development of active NS2B-N3 protease inhibitors.

In the present study, silver complex with 8-hydroxyquinoline (8-HQ) was synthesized and characterized by FT IR and UV-VIS spectroscopic methods. The stoichiometric ratio, molar absorptivity, and formation constant were evaluated using UV-VIS spectrophotometric method. Both oxygen and nitrogen atoms from 8-HQ were included in the complex formation as stated by the spectral data. The UV-VIS spectrophotometric data indicated the formation of (1:1) complex with a formation constant of 4.2x108. Also, the antimicrobial effects of the ligand and the complex were examined in vitro. The diffusion style was used to investigate the antimicrobial activity on some chosen gram-positive and gram-negative bacteria. The ligand and its metal complex possessed antibacterial activity for particular bacteria such as Staphylococcus aureus and Proteus spp. The antimicrobial activity of the complex was higher with gram-negative bacteria. Meanwhile, the 8-HQ was found to have an appreciably higher capability to inhibit the growth of the gram-positive bacteria.

Tuberculosis remains a significant infectious disease-causing over 1.8 million deaths a year, making it one of the world’s most deadly human pathogens. Phytochemicals from natural products are intensely becoming alternative sources of antimicrobial agents with striking mechanisms of action and common side effects compared to synthetic drugs such as isoniazid (−4.7 kcal/mol), pyrazinamide (−4.4 kcal/mol), and ethambutol (−4.5 kcal/mol). Isolated phytochemicals from the bark of Syzygium cordatum were evaluated for antimicrobial activity against mycobacterium tuberculosis through molecular docking. It was observed that quite a number of the phytochemicals have good binding affinities much better than those of the commonly used first-line drugs. Pharmacokinetics analysis of these phytochemicals revealed that binding affinity alone is not enough to prove the potency of a promising drug candidate. Only 7 compounds among the 18 screened compounds passed all the analyses and are identified as potential mycobacterium tuberculosis (4RHT) inhibitors. This study thereby recommends Arjunolic acid (−8.2 kcal/mol), Caffeic acid (−5.8 kcal/mol), Cinnamic acid (−5.6 kcal/mol), Epifriedelinol (−8.9 kcal/mol), Friedelin (−8.8 kcal/mol), Hexahydroxydiphenic acid (−6.6 kcal/mol) and Sinapic acid (−5.3 kcal/mol) as potential inhibitors of mycobacterium tuberculosis (4 RHT) with better pharmacokinetics and bioavailability.

Due to the legitimate crystal size of SrTiO3, in this work, a synthesized compound was introduced and structurally characterized as the quantum dots. The crystal of SrTiO3 was designed using computational tools. There is no obtainable information for hypothetical and conceptual studies, and computational studies. First, using the CASTAP code from material studio 8.0 the structural geometry was optimized using the generalized gradient approximation (GGA) with the hybrid functional, Perdew-Burke-Ernzerhof (PBE) to calculate the electronic structure, geometry, and optical properties for the SrTiO3. The crystal size of the optimized structure was 2.0 nm for both SrTiO3 and SrTi0.94Ag0.06O3, which stays in quantum dots. With the help of GGA with PBE,  the band gap was recorded at 1.77 eV, and for evaluating the nature of 5s, 4p, and 3d orbitals for a Sr atom, 4s, 3p and 3d orbitals for Ti atom, 5s, 4p, and 4d orbitals for Ag atom and 2s, and 2p orbitals for O atom for SrTiO3 are obtained. Density of state(DOS) and the partial Density of state(PDOS) of SrTi0.94Ag0.06O3 were replicated. The optical properties, like absorption, reflection, refractive index, and conductivity, were replicated, dielectric function and loss function was computed. By replacing the Ti atom on SrTiO3 6% Ag atom was doped to elaborate the demeanor nature, and because of this 0.00 eV band gap was obtained having a molecular formula by SrTi0.94Ag0.06O3 , as well as the optical conductivity and optical absorption was soared compared with parent SrTiO3.

Dengue fever is the most common and important arthropod-borne viral illness in humans. However, no effective medications or vaccinations exist to prevent this condition. The dengue viral (DENV) protease non-structural protein (NS) 2B-3 is a possible target for antiviral treatment. Based on the lead compound reported in our earlier study, eight phthalazinone analogues were designed using a structure-based drug design approach, which involved systematic alterations to the various positions of the benzyl ring bearing carbamate pharmacophore and carbamate terminal chain length of the lead. These compounds were also evaluated for in silico ADME properties and drug-likeness. The molecular docking scores of the design ligands were greater than the template’s binding score, ranging from-8.9 to-9.60 kcal/mol, and also higher than those of the Ribavirin and the co-crystalized protease ligand, which were -8.90, -6.10, and -8.10 kcal/mol, respectively. All of the developed ligands satisfied Lipinski's requirements with good synthetic accessibility (3.07–3.41) and a better ADME profile than the template, indicating that they were highly bioavailable and simple to synthesize in the laboratory. Phthalazinone derivatives with higher binding scores (-9.0 to -9.60 kcal/mol) were designed and found to interact well with the DENV NS2B-NS3 protease. The compounds also have significantly improved pharmacokinetic and ADME properties compared to their parent template. The designed compounds could be used as a starting point for developing potent DENV NS2B-NS3 protease inhibitors with suitable pharmacokinetic and ADME properties.