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281.
5-episinuleptolide (1) is an abundant norcembranolide diterpene isolated from several species of the soft coral genus Sinularia. Biocatalytic transformation studies of 1 using Streptomyces lavendulea ATCC 8664 resulted in the isolation and characterization of two new metabolites 2 and 3. Compound 2, 6alpha-hydroxy-5-episinuleptolide was produced via a stereoselective reduction of 1 and was further metabolized into compound 3 which has a 3,8-bicylized cembranoid skeleton. The structures and configurations of the metabolites were determined by spectroscopic and X-ray crystallographic analyses. 相似文献
282.
N. Khalifa B. Yacoubi I. Attar A. Bardaoui R. Chtourou 《Colloid and polymer science》2013,291(11):2705-2709
In this work, we study the inclusion mechanism of Fe3+ ions in a polyvinyl alcohol (PVA) matrix. Thin films of pure and FeCl3-doped PVA on silicon substrates, prepared by the spin-coating method, are investigated using spectroscopic ellipsometry (SE) and Fourier transform infrared (FT-IR) spectroscopy. SE measurements of PVA and Fe3+-doped thin films are carried out at an incidence angle of 75° over the wavelength range of 0.24–1.1 μm. An optical model is used to obtain the refractive index (n) and the extinction coefficient (k). The gap energy E g is afterwards evaluated. The Fe3+ doping is found to affect strongly the optical parameters of the polymer films. In fact, an increase in the refractive index with doping is observed, resulting from the intermolecular hydrogen bonding between Fe3+ ions with the adjacent OH group of PVA. The increase of the thin films' absorption with doping is estimated by the k spectral profile analysis. The gap energy is then calculated and shows an important decrease with the Fe3+ filling, more pronounced for low doped samples. Such a behavior is confirmed by FT-IR analysis. 相似文献
283.
Nagy M. Khalifa Mostafa M. Ramla Abd El-Galil E. Amr Mohamed M. Abdulla 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):3046-3062
A series of some new acetylated S-glycosides of pyridine-2-thione derivatives, including D-glucose, D-galactose, D-xylose and L-arabinose derivatives were synthesized. Oxidation of some formed S-glycosides derivatives with H2O2 afforded the corresponding sulfones. S-Alkylation of pyridine-2-thione derivatives was performed to furnish the S-acyclo deazauridine derivatives. The entire tested compound showed potent anti-inflammatory activity were potent against edema and in the same time inhibited the prostaglandine formation. It is work mention that all the tested compounds showed high safety margin. The structures of the new synthesized compounds have been proved by IR, 1 HNMR, mass spectra and elemental analysis. 相似文献
284.
Antifungal Activity of Soft Tissue Extract from the Garden Snail Helix aspersa (Gastropoda,Mollusca)
Hoda H. Abd-El Azeem Gamalat Y. Osman Hesham R. El-Seedi Ahmed M. Fallatah Shaden A. M. Khalifa Mohamed M. Gharib 《Molecules (Basel, Switzerland)》2022,27(10)
Gastropods comprise approximately 80% of molluscans, of which land snails are used variably as food and traditional medicines due to their high protein content. Moreover, different components from land snails exhibit antimicrobial activities. In this study, we evaluated the antifungal activity of soft tissue extracts from Helix aspersa against Candida albicans, Aspergillus flavus, and Aspergillus brasiliensis by identifying extract components using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Two concentrations of three extracts (methanol, acetone, and acetic acid) showed antifungal activity. Both acetone (1 g/3 mL) and acetic acid extracts (1 g/mL) significantly inhibited C. albicans growth (p = 0.0001, 5.2 ± 0.2 mm and p = 0.02, 69.7 ± 0.6 mm, respectively). A. flavus and A. brasiliensis growth were inhibited by all extracts at 1 g/mL, while inhibition was observed for acetic acid extracts against A. brasiliensis (p = 0.02, 50.3 ± 3.5 mm). The highest growth inhibition was observed for A. flavus using acetic acid and acetone extracts (inhibition zones = 38 ± 1.7 mm and 3.1 ± 0.7 mm, respectively). LC-MS-MS studies on methanol and acetone extracts identified 11-α-acetoxyprogesterone with a parent mass of 372.50800 m/z and 287.43500 m/z for luteolin. Methanol extracts contained hesperidin with a parent mass of 611.25400 m/z, whereas linoleic acid and genistein (parent mass = 280.4 and 271.48900 m/z, respectively) were the main metabolites. 相似文献