GC/MS analysis and antimicrobial activity of the essential oil of fresh leaves of Eucalytus globulus, and leaves and stems of Smyrnium olusatrum from Constantine (Algeria)

The essential oils of fresh leaves of Eucalyptus globulus L. (Myrtaceae), and leaves and stems of Smyrnium olusatrum L. (Apiaceae), obtained by hydrodistillation in a Clevenger-type apparatus, were analyzed by GC/MS. Twenty compounds were characterized, representing 98.3% of the essential oil of E. globulus, with 1,8-cineole (48.6%), globulol (10.9%), trans-pinocarveol (10.7%), and alpha-terpineol (6.6%) as main components, while thirty-three compounds were characterized, representing 94.3% of the essential oil of S. olusatrum, with sabinene (27.1%), curzerene (13.7%), methyl-1-benzyl-2-oxocyclooctane carboxylate (12.3%), alpha-pinene (7.2%), cryptone (7.1%) and beta-pinene (5.7%) as the major components. The essential oils of E. globulus and S. olusatrum were tested against a wide range of fungal and bacterial strains. Both oils showed significant antimicrobial activity.     

Simultaneous fabrication of superhydrophobic and superhydrophilic polyimide surfaces with low hysteresis

Polyimide is of great interest in the field of MEMS and microtechnology. It is often used for its chemical, thermal, mechanical, and optical properties. In this paper, an original study is performed on controlled variation of polyimide film wettability. A two-step microtexturing method is developed to transform hydrophilic polyimide surfaces into a superhydrophobic surface with low magnitude of hysteresis (Δθ ≈ 0° and contact angle θ ≈ 158°). This method is based on the conception of a new kind of fakir surface with triangular cross-section micropillars, the use of a two-scale roughening, and a C(4)F(8) coating. We demonstrate that the absence of hysteresis is related to a combination of two scales of structuring and the pillar shape. The technology that has been developed results in the simultaneous fabrication of adjacent superhydrophobic and superhydrophilic small areas, which allows an effect of self-positioning of water droplets when deposited on such a checkerboard-like surface.     

Textural,structural and catalytic behavior of low specific area silica-supported copper catalysts: effect of preparation method

Supported copper catalysts on low surface area silica were prepared by several methods and characterized by AAS, XRD, N₂ adsorption, SEM, H₂-TPR, N₂O titration, TGA-DTA, UV–Vis techniques. Their hydrogenating properties were examined in the gas-phase hydrogenation of benzaldehyde. The analysis of characterization results revealed that the choice of preparation method affected the texture, composition, and structure of the calcined and reduced Cu/SiO₂ catalysts. The dispersion and size distribution of copper species was present in different forms in the catalysts that exhibited low specific surface areas. In gas-phase hydrogenation of benzaldehyde to benzyl alcohol, the catalysts tested at the reaction temperatures of 160 and 200 °C were stable and conducted to a good catalytic activity and benzyl alcohol selectivity ranging between 5 and 39 µmol min^?1 g^?1 and 0–95%, respectively. The activity of the catalysts in gas-phase hydrogenation also depended on the particle size and the nature of copper species formed on low surface area silica.     

Chemical composition and antioxidant activity of aerial parts of Ferula longipes Coss. ex Bonnier and Maury

This is the first study on the phytochemistry and antioxidant activity of Ferula longipes Coss. ex Bonnier and Maury (Apiaceae). A new flavonoid quercetin-3-O-α-L-rhamnopyranoside-7-O-ß-D-[2-O-caffeoyl]-glucopyranoside (1), along with 10 known compounds kaempferol-3-O-α-L-rhamnopyranoside (2), quercetin-3-O-α-L-rhamnopyranoside (3), kaempferol-3-O-ß-D-glucopyranoside-7-O-α-L-rhamnopyranoside (4), isorhamnetin-3-O-α-L-rhamnopyranoside-7-O-ß-D-glucopyranoside (5), quercetin-3-O-α-L-rhamnopyranoside-7-O-ß-D-glucopyranoside (6), isorhamnetin-3,7-di-O-β-D-glucopyranoside (7), apigenin (8), apigenin-7-O-ß-D-glucopyranoside (9), 3,5-dicaffeoylquinic acid (10), deltoin (11) were isolated from the aerial parts of Ferula longipes Coss. Structures elucidation was performed by comprehensive 1D and 2D NMR analyses, mass spectrometry and by comparison with literature data. The compounds 1, 3, 4, 6, 7 and 10 were evaluated for their antioxidant activity, compound 1 exhibited the best antiradical activity potential and showed IC₅₀ and A_0.5 values 5.70, 7.25, 5.00, and 2.63 μg/mL towards DPPH free radical-scavenging, ABTS, CUPRAC, and reducing power assays, respectively compared with BHA, BHT and ascorbic acid which were used as positive controls.     

A green route to enantioenriched (S)-arylalkyl carbinols by deracemization via combined lipase alkaline-hydrolysis/Mitsunobu esterification

Herein we report results of the chemoenzymatic deracemization of a range of secondary benzylic acetates 1a–9a via a sequence of hydrolysis with CAL-B lipase in non-conventional media, combined with esterification of the recovered alcohol according to the Mitsunobu protocol following an enzymatic kinetic resolution (KR). The KR of racemic acetates 1a–9a via an enzymatic hydrolysis, with CAL-B lipase and Na₂CO₃, in non-aqueous media was optimized and gave high selectivities (E ? 200) at good conversions (C >49%) for all of the substrates studied. This method competes well with the traditional one performed in a phosphate buffer solution. The deracemization using Mitsunobu inversion gave the (S)-acetates in moderate to excellent enantiomeric excess 75% < ee < 99%, in acceptable isolated yields 70% < yield < 89%, and with some variations according to the acetate structure.     

Solvent-dependent oxidations of 5- and 6-azaindoles to trioxopyrrolopyridines and functionalised azaindoles

A regioselective synthesis of 4,7-dimethoxy 5- and 6-azaindoles 2 has been achieved, based on the appropriate choice of ortho-directing or ortho-repulsing groups in the formylation of a pyridine ring. Studies on the regioselectivity of the formylation step and on the preparation of azidoacrylate intermediates 4 are described in this paper. The reactivity of the 5- and 6-azaindole structures towards BBr3-mediated selective monodemethylation and oxidative demethylation reactions were also investigated. The regioselectivity of the deprotection was confirmed using a chemical approach. Oxidation reactions were then carried out on either dimethoxy- or hydroxymethoxyazaindoles, in different solvents, using [bis(trifluoroacetoxy)iodo]benzene. In acetonitrile-water, trioxopyrrolopyridines 12 were obtained, whereas the formation of functionalised azaindoles 17 was observed in acetonitrile-methanol. The tautomeric structure of the trioxopyrrolopyridines was proved by X-ray diffraction analysis.     

Determination of total sterols in brown algae by Fourier transform infrared spectroscopy

A procedure is proposed for the determination of the total amount of sterols in brown algae Bifurcaria bifurcata, Cladostephus hirsitus, Dictyota dichotoma and Cystoseira sedoides, globally determined as fucosterol, which is the major sterol contained in these algae. The method involves the use of cholesterol as reference standard and a correction factor of 1.259 ± 0.003, which represents the ratio between the slopes of calibration lines obtained from fucosterol and cholesterol. The method provides precise and accurate results for the IR analysis of real samples.