Synthèse et réactivité des dérivés de la quinoléine : préparation des isoxazoles et isoxazolines quinoléiques par des réactions de cycloaddition 1,3-dipolaires

The main objectif of this work is the synthesis of new five-membred heterocycles containing the quinoline moeity via a 1,3-dipolar cycloadition reaction of nitrile oxide with dipolariphiles in goal of discover a new compounds potentially actives in different domains notably in pharmacy and biology

One-Step Chemiluminescent Assay for Hydrogen Peroxide Analysis in Water

The detection of hydrogen peroxide is of great importance in the environmental field. For this, a homogeneous technique has been developed here for sensitive and rapid quantification of hydrogen peroxide. In this technique, hemoglobin was used as a bioreceptor, where heme groups acted as electroactive centers to catalyze hydrogen peroxide reduction. The chemiluminescence reagent luminol is also a peroxidase substrate and can be oxidized by hemoglobin—thus generating a CL signal. The principle of the designed biosensor was based on the competition between hydrogen peroxide and luminol towards hemoglobin. Under optimized conditions, the chemiluminescent signal decreased with increasing hemoglobin concentrations within the linear range of 0.5 to 12 mM, with a correlation coefficient R2 of 0.99762. The limit of detection was calculated to be as low as 0.308 mM. The selectivity of the biosensor was successfully demonstrated against different interferents. The developed strategy provides a one step, simple, and low-cost bioanalytical method which can be applied for the monitoring of other peroxidase substrates

Ferulenol specifically inhibits succinate ubiquinone reductase at the level of the ubiquinone cycle

The natural compound ferulenol, a sesquiterpene prenylated coumarin derivative, was purified from Ferula vesceritensis and its mitochondrial effects were studied. Ferulenol caused inhibition of oxidative phoshorylation. At low concentrations, ferulenol inhibited ATP synthesis by inhibition of the adenine nucleotide translocase without limitation of mitochondrial respiration. At higher concentrations, ferulenol inhibited oxygen consumption. Ferulenol caused specific inhibition of succinate ubiquinone reductase without altering succinate dehydrogenase activity of the complex II. This inhibition results from a limitation of electron transfers initiated by the reduction of ubiquinone to ubiquinol in the ubiquinone cycle. This original mechanism of action makes ferulenol a useful tool to study the physiological role and the mechanism of electron transfer in the complex II. In addition, these data provide an additional mechanism by which ferulenol may alter cell function and demonstrate that mitochondrial dysfunction is an important determinant in Ferula plant toxicity

Comparative study of antibiofilm, cytotoxic activity and chemical composition of Algerian propolis

Antimicrobial agents are one of the strategies for inhibition of biofilm formation. But, most antimicrobials are not often effective in controlling of biofilm formation. Therefore, finding of new materials that have biofilm inhibitory effects is so important. In this regard, we aimed to determine the antibiofilm and cytotoxic effect of five Algerian propolis extracts obtained by extraction in solvents of varying polarity. Propolis extracts were tested for their ability to inhibit biofilm formation and to reduce preformed biofilm of eight bacterial strains including reference strains of Staphylococcus aureus (S. aureus ATCC29213 and S. aureus ATCC33862), three methicillin-resistant S. aureus (M10-1, M18-3, and M20-1), Enterococcus faecalis ATCC19433, Micrococcus luteus NRRL-B1013, and Yersinia enterocolitica RSKK1501. Cytotoxic activities of propolis extracts were determined using MTT test. Chemical investigation was performed using ultra-performance liquid chromatography with electrospray ionization coupled to tandem mass spectrometry (UPLC-ESI-MS/MS). All tested extracts exhibited the highest eradicating capability for S. aureus reference strains and methicillin-resistant strains, especially MRSA18-3 and MRSA20-1.The reduction of biofilm formation was found to be significantly affected by the used solvent for maceration, the tested bacterial strains, and the origin of tested propolis. In addition, biofilm reduction of Algerian propolis seemed to be dose-dependent. Moreover, all extracts showed high cytotoxic activity in colon adenocarcinoma cells. In addition, twenty-six phenolic compounds were detected. Difference between the amounts of detected compounds was found to be significant. Caffeic and ferulic acids were the main compounds in the tested extracts. These results suggest that those compounds might be responsible for the observed antibiofilm and cytotoxic activities of propolis extracts. © 2019, © 2019 International Bee Research Association

Isolation and identification of five free flavonoid aglycones from Thymus numidicus

International audienceFrom the aerial parts of the endemic species Thymus numidicus Poiret locally which is known as "zaatar", belongs to the Lamiaceae family five flavonoids were isolated using chromatographic techniques and identified by spectral analysis (UV-Visible, MS, 1H and 13CNMR) and chromatographic behaviours

Volatiles of Algerian Daucus rebaudii Coss. rich in (E)-anethole and their antioxidant activity

The essential oils obtained from the aerial parts of Daucus reboudii Coss. (Apiaceae) which is endemic to north Africa collected from Algeria were analyzed by GC/MS. 28 compounds were identified accounting for 97.8% of the total oil, the result shows the dominance of the phenylpropanoids derivatives. (E)-anethol (59.4%) was the main constituents identified in the essential oil, followed by estragol (21.2%) and dodecanal (4.4%). In vitro antioxidant antioxidant activity of the Essential oils were assayed using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, ß- carotene and ABTS+ assay, the results indicated that D.reboudii oil recorded a moderate capacit

Ferulsinaic acid, a sesquiterpene coumarin with a rare carbon skeleton from Ferula species

Fractionation of methylene chloride extracts of the resin of Ferula vesceritensis and F. sinaica afforded three new sesquiterpene coumarins and a new glucose derivative. One of them was a sesquiterpene with a rare carbon skeleton. The structures of these compounds were determined by extensive NMR studies, including DEPT, COSY, NOE, HMQC, and HMBC

Disruption of mitochondrial membrane potential by ferulenol and restoration by propolis extract: Antiapoptotic role of propolis

This paper reports an investigation of the ability of propolis extract (a resinous substance collected by honeybees from various plant sources) to restore the collapse of mitochondrial membrane potential induced by ferulenol, a sesquiterpene prenylated coumarin derivative isolated from the plant Ferula vesceritensis . We show that ferulenol was able to induce the permeability transition pore (PTP) opening. This effect is caused by the interaction of the compound with the mitochondrial respiratory chain, more particularly by the fall of membrane potential and the inhibition of complex II. We have previously demonstrated that this inhibition results from a limitation of electron transfers involved in the respiratory chain and initiated by the reduction of ubiquinone. We hypothesized that the protective effect of propolis could be due to a direct action on mitochondrial functions. So we have investigated in vitro the mitochondrial effects of Algerian propolis using rat liver mitochondria, by analysing their effects on membrane potential, mitochondrial respiration and mitochondrial swelling. We show that propolis extract was able to restore the fall of mitochondrial membrane potential. Taken together these data reveal that propolis extract may be an interesting inhibitor of PTP and provide an additional mechanism by which the natural product propolis extract may restore the mitochondrial membrane potential and to prevent apoptotic process