Structures, Lipophilicity, Dipole Moments, Acidity and Spectroscopic Properties of Non-Steroidal Anti-Inflammatory Drugs Diclofenac, Bromfenac and Amfenac: A Theoretical Study

This work is a contribution of theoretical chemistry to the classification of some non-steroidal anti-inflammatory drugs (NSAIDs). Indeed, research on the efficacy of NSAIDs has shown that no NSAID is recognized as the most efficient anti-inflammatory drug. We have made a theoretical study of diclofenac, bromfenac and amfenac, in order to compare their efficacy from some physicochemical properties. To do this, we used the DFT and TD-DTF methods at the B3LYP/6-311+G(d, p) level theory. The lipophilicity study shows that diclofenac and bromfenac are very lipophilic. Acidity study shows that diclofenac is more acid than bromfenac and amfenac. The results from molecular orbital and the TD-DFT calculations reveal that for the three NSAIDs, the lowest energy transition is due to the excitation from HOMO to LUMO. The absorption energy corresponding to H→L transition is comparable with the energy gap value. Our findings have shown that bromfenac is more reactive than amfenac, which is more reactive than diclofenac.

7-(2-Ethyltiophenyl) Theophylline as Copper Corrosion Inhibitor in 1M HNO₃

7-(2-ethyltiophenyl) theophylline was used as copper corrosion inhibitor in 1M HNO3 solution. The study was performed using mass loss, scanning electron microscopy (SEM) and Density Functional Theory (DFT) methods. The results show that the inhibition efficiency increases up to 91.29% with increase of the inhibitor concentration (from 0.05 to 5 mM) but decreases with raising temperature of the solution. Copper dissolution was found to be temperature and 7-(2-ethyltiophenyl) theophylline concentration dependent. The thermodynamic functions related to the adsorption of the molecule on the copper surface and that of the metal dissolution were determined. The results point out a spontaneous adsorption and an endothermic dissolution processes. Adsorption models including Langmuir, El-Awady and Flory-Huggins isotherms were examined. The results also suggest spontaneous and predominant physical adsorption of 7-(2-ethyltiophenyl) theophylline on the metal surface which obeys Langmuir isotherm model. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on copper surface. Furthermore, the global and local reactivity parameters of the studied molecule were analyzed. Experimental and theoretical results were found to be in good agreement.

Nicotinamide Inhibition Properties for Copper Corrosion in 3.5% NaCl Solution: Experimental and Theorical Investigations

This work reports the inhibition properties of nicotinamide (NAM) for copper protection during its applications in seawater systems such as water pipelines, shipbuilding, seawater desalination and heat exchange systems. The efficiency of NAM as a copper corrosion inhibitor in simulated seawater (3.5% NaCl solution) was investigated by Tafel extrapolation and linear polarization methods in the temperature range from 20℃ to 50℃. The corrosion parameters and the adsorption isotherms were determined using potentiodynamic polarization techniques. It was found that the inhibition efficiency (η) and the coverage rate (θ) increase up 80% at 25℃ for nicotinamide concentration of 10 mM but decrease as the temperature of the solution increases. Moreover, the obtained thermodynamic parameters using Langmuir model suggested a physical adsorption type. A correlation was found between the corrosion inhibition efficiency and the global theoretical parameters obtained by the functional density method B3LYP/ 6-31 + G (d, p). Local parameters such as condensed Fukui functions [f(r)] and condensed local softness [s(r)] indices have also been determined to obtain a chemical insight into atoms that have a significant tendency toward donation or acceptance of whole or fraction of electrons.

Mercury Concentration Profile in Sediment Cores of a Tropical Lagoon under High Anthropogenic Activities around an Urban City—Abidjan, Côte d’Ivoire

The present study focuses on the quantification of mercury in sediment cores from Cocody, Banco, Koumassi and Milliardaires bays in Abidjan, Côte d’Ivoire. It aims at assessing the state of mercury contamination of the lagoon bottom using DMA-80 (Direct Mercury Analyser). The automatic analyzer DMA-80 mercury is an innovative instrument for the analysis of mercury at very low content in solid and liquid samples in five minutes, without requiring any prior steps of pretreatment wet. The results showed, according to the lithological description of different bays, that the cored sediments consist of mud, sand, sandy mud or muddy sand with occasional shells. In addition, our results showed the presence of mercury in the sediments of the lagoon bottom at a degree of contamination that varies from moderate to very high according to the calculated contamination factor (CF) values. The highest contamination was observed in Cocody Bay at the surface with a contamination factor of 7.5, while the lowest contamination was observed in Milliardaires Bay at the water-sediment interface with a contamination factor of 1.67. In addition, mercury concentrations compared to sediment guide values (SQGs) reveal that these sediments mostly show occasional biological effects but no toxicity except Koumassi core (sediments at 20 cm depth). Also, dredging, hydrodynamics have probably impacted the mercury content. The depositional environment of mercury metal is therefore a limiting factor for its fate in the aquatic environment.

Phytochemical Study and Comparative Antioxidant Activity of Extracts from Aerial Parts of <i>Chenopodium ambrosioides</i>Linn. (Chenopodiaceae)

The use of Chenopodium ambrosioides in some communities in Togo reveals its importance and its medicinal properties. The plant is often infused for medicinal drinks before use. Thus, through a comparative study, this work focused on the identification of the different phytochemical groups and then on the anti-radical capacities of ethanolic and aqueous extracts of aerial parts (lea- ves and seeds) of Chenopodium ambrosiooides obtained by maceration and infusion. The phytochemical tests, carried out on the various extracts, showed that they contained certain biomolecules such as flavonoids and tannins. Likewise, the presence of terpenoids and terpenes has been detected. However, it is only in aqueous extracts that the alkaloids have been revealed. The determination of the polyphenol content of the extracts revealed that the aqueous infusion contains 25.699 mgGAE/g DE, followed by the aqueous maceration: 24.873 mgGAE/g DE, after the ethanolic infusion: 21.009 mg GAE/g DE and of the ethanolic maceration: 20.625 mg GAE/g DE. The results of the determination of the anti-radical capacity by the DPPH method after calculation of the IC50, revealed that the infusion gives respectively in aqueous and ethanolic medium: 25.541 μg/ml and 48.269 μg/ml while the maceration leads to 29.187 μg/ml 50.999 μg/ml respectively. This study showed that each extract reacted with DPPH and the aqueous infusion was the most reactive.

Chemical Composition of Different Extracts of Conyza bonariensis: Insecticidal and Nematicidal Activities

C. bonariensis (L.) Cronq. known as hairy fleabane was first described in Argentina but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. In this work, a chemical analysis by liquid and gas chromatography coupled with mass spectrometry of the whole plant, aerial part, flowers and roots extracts of C. bonariensis harvested in Togo (West Africa) was carried out. Two acetylenic compounds Lachnophyllum ester and limonene were identified as the main components of essential oils while Lachnophyllum and Matricaria lactones were dominant in chloroform extracts. Based on the plant chemical compositions, essential oils and chloroform extracts were tested on cowpea weevil Callosobruchus maculatus adults which are considered as one of the most cosmopolitan pests of stored beans, and on freshly hatched second-stage juveniles of root-knot nematode Meloidogyne incognita. Results showed that the whole plant essential oil demonstrated an LC50/24h value of 1.75 μL oil/L air on C. maculatus while at 3.91 μL oil/L air, it showed 100% mortality. Furthermore, the plant root chloroform extracts partitioned in diethyl ether-hexane mixture showed the strongest nematicidal activity with an LC50/72h value of 0.47 mg/mL. Our findings suggest that the widely diffused plant C. bonariensis and its acetylenic constituents could be considered as potent botanical insecticidal and nematicidal agents.

Physico-Chemical Characterization of Nine Agricultural Biomasses of the Togolese Flora

Green coal or bio-coal is coal produced with rich biodegradable materials, elaborated from agricultural and household residues with a high percentage of carbon. This green charcoal (fuel briquettes) is an alternative to charcoal. Well known for its contribution to greenhouse gas emissions, charcoal is one of the causes of tree felling. The valorization of waste by the manufacture of biofuels could be an alternative to the use of charcoal. The general objective of the present study is the valorization of nine biomasses from Togo as raw materials. Specifically, physico-chemical characteristics such as dehydration, acidity, and conductivity were determined. Information on the structure and composition of the biomass was found. These data on the nature of the biomass were found through the use of Fourier Transform Infrared (FTIR) and Thermogravimetry (TGA). The promising results inform on the nature of the analyzed samples and allow the selection of the best biomass which would give an important thermal conductivity for the manufacture of the briquettes, but also of the binders to be used according to the physico-chemical characteristics like the pH.