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  • Author: Abdenabi Abidi x
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Abstract

Interest in nanomaterials, especially metal oxides, in the fight against resistant and constantly changing bacterial strains, is more and more expressed. Their very high reactivity, resulting from their large surface area, promoted them to the rank of potential successors of antibiotics.

Our work consisted of the synthesis of zinc oxide (ZnO) and copper oxide (CuO) in the nanoparticle state and the study of their bactericidal effect on various Gram-negative and Gram-positive bacterial strains.

The nanoparticles of metal oxides have been synthesized by sol-gel method. Qualitative analysis and characterization by UV / Visible and infrared spectrophotometry and X-ray diffraction confirmed that the synthetic products are crystalline. The application of the Scherrer equation allows to determine the size of the two metal oxides, namely: 76.94 nm for ZnO and 24.86 nm for CuO.

The bactericidal effect of ZnO and CuO nanoparticles was tested on Gram-positive bacteria (Staphylococcus aureus, Staphylococcus hominis, Staphylococcus haemolyticus, Enterococcus facials) and Gram-negative bacteria (Escherichia coli, Schigella, Klepsiella pneumoniae and Pseudomonas aeruginosa). The results indicate that the tested metal oxides nanoparticles have an effect that varies depending on bacterial species. Indeed, Gram-positive bacteria show greater sensitivity to ZnO nanoparticles whereas Gram-negative bacteria are more sensitive to CuO nanoparticles.

Abstract

The objective of the present study was the optimization of the parameters affecting the hydrodistillation of Ruta chalepensis L. essential oil using response surface design type Box-Behnken. After an appropriate choice of three parameters, 15 experiments were performed leading to a mathematical second-degree model relating the response function (yield of essential oil) to parameters and allowing a good control of the extraction process. The realization of the experiments and data analysis was carried out by response surface methodology (RSM). A deduced second-order polynomial expression was used to determine the optimal conditions necessary to obtain a better essential oil yield. These optimized operating conditions were: a granulometry of 2 mm, a condensation-water flow rate of 3.4 mL/min and an extraction time of 204 min. Analysis of variance (ANOVA) indicates that the generated second-order polynomial model was highly significant with R2=0.9589 and P<0.006. The gas chromatography-mass spectrometry analysis of essential oil extracted from the Ruta chalepensis L. aerial parts revealed the presence of 2-undecanone, 2-nonanone and 2-decanone as major components.

Abstract

The aerial parts of Tamarix gallica L. taken from three different climatic stages in Algeria (Oum El Bouaghi: Semi-arid, ElTaref: Humid, and Ouargla: Arid) were extracted using boiling distilled water. The crude extracts were subjected to total phenolics and flavonoids quantifications in addition to anti-proliferative assessment against two tumor cell lines namely rat brain tumor (C6) and human cervix carcinoma (HeLa) using BrdU (bromo-deoxyuridine) ELISA(Enzyme-linked immune-sorbent assay) and xCELLigence assay. The total phenolics yield was found to range between 16.14 and 39.32 mg GAE (Gallic acid equivalent)/g of extract and a flavonoids yield ranging between 16.51 and 20.35 mg QE(quercetin equivalent)/g of extract. The various phenolics were identified using HPLC-TOF/MS to highlight hesperidin and rosmarinic Acid as major components. Moreover, the extracts exhibited different levels of antitumor potency against C6 and HeLa cell lines depending upon the climatic stage and the concentration. A good cytotoxic effect was recorded with the species collected from the humid region at 250 μg/mL. On the contrary, the other extracts revealed a weak activity for both tests.