வேதியியல் அறிவியல் இதழ்

Amodaquine [4-[(7-chloroquinolin-4-yl) amino]-2-(diethylaminomethyl) phenol] and nivaquine (4-N-(7- chloroquinolin-4-yl)-1-N,1-N-diethylpentane-1,4-diamine sulphate) has been studied as potential source of green inhibitor for corrosion of aluminium in 1 M HCl at different concentrations using gravimetric method. To further elucidate the reactivity and efficiency of these anti-malaria drugs as potential corrosion inhibitors, quantum chemical calculations using Density Functional Theory (DFT) method in conjuction with Becke 3 Lee Yar Parr (B3LYP)/6-311++G** level of theory was applied. Kinetics and thermodynamic parameters central to surface adsorption were calculated and discussed. Results revealed that the inhibition efficiency increased as the inhibitor concentration increased but decrease with an increase in temperature with Nivaquine having better inhibition efficiency than Amodaquine. The adsorption of Amodaquine and Nivaquine on the surface of aluminium both followed the Freundlich adsorption isotherm at all concentrations and temperatures. The negative value of ΔGads obtained indicates spontaneous adsorption of the inhibitor on the aluminium surface and a low negativity indicates electrostatic interactions between inhibitor and the charged metal surface.

Eucalyptus camaldulensis essential oils are aromatherapy agents in medicine. This study examined the phytochemicals and therapeutic activities of the seed essential oils of E. camaldulensis var. nancy and E. camaldulensis var. petford from Nigeria. The seed essential oil was extracted by hydrodistillation and analyzed using GC and GC-MS. TPC, antioxidant, anti-inflammatory, antinociceptive and antimicrobial activities were measured by Folin-Ciocalteu’s, DPPH, FRAP, carrageenan, formalin and agar-well diffusion methods respectively. GC and GCMS analyses of the essential oils led to the identification of 23 and 15 constituents representing 99.2% and 98.5% of the oil of E. camaldulensis var. nancy and E. camaldulensis var. petford, respectively. The main components in the seed essential oils of E. camaldulensis var. nancy and E. camaldulensis var. petford was 1,8-cineole (40.8%) and (52.0%) respectively. The TPC values of the oils were 156.25 ± 0.00 and 167.93 ± 0.00 µg GAE/mg respectively. The seed essential oils achieved optimum antioxidant potentials with IC50 values of 3.50 µgml-1. The seed essential oils have high reducing antioxidant activities, with EC50 values of 5.0 µgml-1 in the two varieties. The essential oils showed significant anti-inflammatory properties with oedema inhibitory percentages of 87.50% and 43.75% respectively and antinociceptive potential with inhibitory percentage at 70.52% and 80.52% in phase I (neurogenic), as well as 99.99% and 41.03% in phase II (anti-inflammatory). The seed essential oils showed efficient antibacterial activities with their zones of inhibitions values ranging between 13-24 mm at 1000-10 µgml-1. The results from this study revealed that the two seed essential oils have potentials as the therapeutic agents.

The kinetic of alkaline hydrolysis of ethyl cinnamate was investigated at different percentage of aqua-organic solvent mixture with Acetone (30 to 70% v/v) over the temperature range of 20°C to 40°C. The specific rate constant was found to be decreased with increasing proportion of solvent (Acetone) at all the temperature range. The Iso-composition Activation energy (EC) was also evaluated which decreases with solvent composition in (water-Acetone) system. The number of water molecule associated with the activated complex is found to be increase (0.7003 to 0.786) in waterAcetone system. The thermodynamic activation parameter such as Enthalpy of Activation (Δ H* ), Entropy of Activation (Δ S* ) and Gibb’s free energy of activation (Δ G* ) were also calculated.