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So far, many efforts have been made to discover phytochemical alternatives to chemically synthesized antioxidants. The candidate groups of natural molecules have appeared to be polyphenols and flavonoids. In this study, the amount of phenolic and flavonoid compounds in aqueous extracts of Melissa Officinalis, from North-East Morocco (TAZA), was explored by using two common approaches (Folin Ciocalteu and Aluminum Chloride). Their antioxidant capacity was assessed by DPPH free radical scavenging assay. The results obtained demonstrated that the two fraction of ethyl acetate and diethyl ether were rich in polyphenols (505 ± 26 and 378 ± 16 μg/mg respectively) and had moderate quantities of flavonoids (8 ± 0.1 and 10 ± 0.2 μg equivalent of routine per mg of extract). At 2 µg/ml the antioxidant activities of two fractions appeared to be a lower (70 and 71%) than that of ascorbic acid (83%)., Moroccan Journal of Chemistry, Vol 9, No 1 (2021)

Date palm (Phoenix dactylifera L.) is an important food source and commercial perennial crop in the Sahara and North Africa. “Bayoud”, a vascular wilt disease, incited by the soilborne fungal pathogen Fusarium oxysporum f. sp. albedinis (FOA), has become a serious threat to date production in date palm-growing regions in Morocco. Substantial body of research reported antifungal properties of a wide range of plant extracts. The present work aims to determine chemical composition and anti-FOA activity of Asteriscus graveolens (Forssk.) Less (AG) essential oil. GC/GC-MS analysis revealed the presence of forty-two distinct chemical components in the essential oil samples. The main compounds of the studied essential oils were 6-Oxocyclonerolidol (7.7–73.8%), cis-8-acetoxychrysanthenylacetate (0.6–50.1%) cis-chrysantenyl acetate (0.3–15.4%), 6-hydroxycyclonerolidol (2–13.3%), τ-cadinol (0.4–12.2%) and α-oxobisabolene (0.2–5.5%). Mycelial growth and spore germination of FOA were found to be strongly inhibited by the oil when tested using agar dilution assay. The lowest essential oil (EO) concentration that inhibits 100% of mycelial growth was 3500 ppm for leaves and 4000 ppm for aerial parts EO. These findings contribute significant insight into the potential of using plant extracts for controlling “Bayoud” disease., Moroccan Journal of Chemistry, Vol 8, No 2 (2020)

The anticorrosion proprieties of Ammodaucus leucotrichus Cosson & Durieu essential oil (ALEO) against the corrosion of tinplate in 0.5M oxalic acid medium was studied in the interest to improve the corrosion resistance of cans in interaction with food contains. For this, the gravimetric test, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used. The different corrosion test used show that the ALEO has an anticorrosion effect with an inhibition efficiency of 83.83% at 4g.L-1, this can be pertained to the chemical composition of the studied essential oil. The essential oil behavior at rang temperature (303-373K) show that ALEO exhibits good inhibition even at moderate to high temperatures. The estimation of the corrosion activation parameters reveal that the essential oil shows good inhibitor characteristics with a physisorption mechanism. By using the scanning electron microscopy and energy dispersive X-rays (SEM-EDX), it is clear that the surface is remarkably improved in the presence of ALEO compared with that exposed to the acid medium without essential oil., Moroccan Journal of Chemistry, Vol 7, No 1 (2019)

The inhibition performance and mechanism of N1,N1,N3,N3-tetrakis((3,5-dimethyL-1Hpyrazol- 1-yl)methyl)propane-1,3-diamine (BF2) and N1,N1,N2,N2-tetrakis((3,5-dimethyl- 1H-pyrazoL-1-yl)methyl) benzene-1,2-diamine (BF4) for the corrosion of mild steel in 1.0 M HCl were investigated using weight loss method and electrochemical measurements. The results show that both tetrakis pyrazole derivatives act as good inhibitors, and inhibition efficiency follows the order: BF4 > BF2. Two tetrakis pyrazole derivatives are mixed type inhibitors exhibiting predominantly cathodic behavior. The Nyquist plots showed that, after increasing inhibitors' concentrations, charge-transfer resistance increased and double-layer capacitance decreased, involving increased inhibition efficiency. The adsorption of both inhibitors on a steel surface obeyed Langmuir model, thus, the thermodynamic and kinetic parameters were calculated and discussed. Quantum chemical parameters are calculated using the Density Functional Theory method (DFT). Correlation between theoretical and experimental results is discussed.

The objective of this work is to characterize the phenols and flavonoids compounds of extracts of Pelargonium Graveolens from North-East Morocco (TAZA) in terms of antioxidant activity. The antioxidant activity of this aromatic plant was determined according to the DPPH radical scavenging assay to suggest it as a new potential source of natural antioxidants. The quantification of phenolics and flavonoids compounds of solvent extracts (diethyl ether and ethyl acetate) were determined spectrometrically. The DPPH scavenging activity of extracts increased in the order diethyl ether extract < ethyl acetate extract < ascorbic acid. Based on these results, we suggest that the phenols and flavonoids compounds of Pelargonium Graveolens have significant potential as a natural antioxidant.

Hydrogen, as chain transfer agent, effects on kinetic of propylene polymerization; consequently variation of hydrogen concentration leads to change final product properties and also activates site of used catalyst. This phenomenon is one of the most important process variables is to adjust the final product properties and optimize the operating conditions. This work has attempted to present a mathematical model that cable to calculate the most important indices of end used product, such as melt flow index , number and weight average molecular weight and poly dispersity index. The model can predict profile polymerization rates determining important kinetic parameters such as the activation energy, lumped deactivation reaction initial reaction rate and deactivation constant. The mathematical model was implemented in Matlab/Simulink environment for slurry polymerization in laboratory scale. The modeling approach is based on polymer moment balance method in the slurry semi-batch reactor. In addition, in this work have provided a model that calculating fraction activated sites catalyst via hydrogen concentration. The model was validated by experimental data from lab scale, reactor. The experimental and model outputs were compared; consequently, the errors were within acceptable range. KEY WORDS : Mathematical modeling, Propylene polymerization, Kinetics study, Hydrogen response, population balance Bull. Chem. Soc. Ethiop. 2018 , 32(2), 371-386. DOI: https://dx.doi.org/10.4314/bcse.v32i2.15

The flora of Saudi Arabia comprises about 18 species of Acacia species including Acacia hamulosa Benth. The methanolic extract of the flowering tops of A. hamulosa was tested for its radical scavenging activity toward 2,2-diphenyl-1-pricylhydrazyl (DPPH) radical and the activity was compared with L-ascorbic acid, quercetin and Trolox as standards. The total phenolic content was determined using Folin-Ciocalteu method. In addition the methanolic extract has been evaluated as a corrosion inhibitor for steel in 1 M HCl solution by means of weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract of Acacia hamulosa acts as a cathodic type inhibitor. Inhibition was found to increase with increasing concentration of the extract of Acacia hamulosa . Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of extract was also studied and thermodynamic parameters were determined and discussed. KEY WORDS : Acacia hamulosa , Extract, Polyphenols, Antioxidant corrosion, Electrochemical study Bull. Chem. Soc. Ethiop. 2018 , 32(2), 323-335. DOI: https://dx.doi.org/10.4314/bcse.v32i2.11

2-Allyl-p-mentha-6,8-dien-2-ols P1−P3 synthesized from carvone P are tested as corrosion inhibitors of steel in 1 M HCl using weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods. The addition of 2-allyl-p-mentha-6,8-dien-2-ols reduced the corrosion rate. Potentiodynamic polarisation studies clearly reveal that the presence of inhibitors does not change the mechanism of hydrogen evolution and that they act essentially as cathodic inhibitors. 2-Allyl-p-mentha-6,8-dien-2-ols tested adsorb on the steel surface according to Langmuir isotherm. From the adsorption isotherm some thermodynamic data for the adsorption process are calculated and discussed. EIS measurements show the increase of the charge-transfer resistance with the inhibitor concentration. The highest inhibition efficiency (92%) is obtained for P1 at 3 g/L. The corrosion rate decreases with the rise of temperature. The corresponding activation energies are determined.

The flora of Republic of Algeria comprises a lot of Palm species, including Phoenix dactylifera. In this work, we used the Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi). The objective of this study is divided into two parts. Firstly, determine the antioxidant activity of Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi) according to the DPPH radical scavenging assay to suggest it as a new potential source of natural antioxidants, secondly, study the effect of inhibiting Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi) on corrosion of mild steel in hydrochloric acid by electrochemical methods. Furthermore, The DPPH scavenging activity of Oil of both Deglet Nour and Kentichi increased in the order, Deglet Nour Oil < Kentichi Oil < ascorbic acid. The results of the polarization curves show that the corrosion current density decreases 577.9 μA/cm2 to 58μA/cm2 and to 59.3 μA/cm2 after addition of the inhibitor (oil of Deglet Nour and Kentichi respectively). The charge transfer resistance increases 21.69 ohm.cm2 to 186.5 ohm.cm2 and to 222.8 ohm.cm2 in the electrochemical impedance spectrum after addition of oil of Deglet Nour and Kentichi respectively. The inhibition of the compound effect is attributed to the formation of a film on the surface of the steel., Moroccan Journal of Chemistry, Vol 5, No 1 (2017)

View the growing success of natural products as an alternative to synthetic chemicals. The purpose of this study was to contribute to the valorization of leaves of Mentha pulegium by determining the chemical composition of its essential oil and evaluate in vitro the antioxidant and the anticorrosive activities of its aqueous extract and essential oil. The essential oil revealed 1,8-Cineole (31.9%) followed by piperitone (15.6%), Limonene (14.6%) and β-Pinene (4.8%) as the main constituents. The antioxidant activity of aqueous extract was evaluated by the method of DPPH radical scavenging. The extract and the essential oil of M. pulegium were tested as corrosion inhibitors of mild steel in 0.5 M H2SO4 using weight loss measurements and electrochemical methods. The aqueous extract exhibited a moderate antioxidant activity compared to acid ascorbic and the IC50 value was 36,62 µg/mL. The obtained results have showed that the inhibition efficiency increases with increasing inhibitor concentration to attain 90.3 % at 2 g/L of MPE and 87.3 % at 4g.L-1 of MPO at 303 K. Finally, extracts and essential oil of M. pulegium from Mediterranean origin have numerous potential as a substitute to chemical additives for the food industry., Moroccan Journal of Chemistry, Vol 5, No 1 (2017)