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111.
Nabil A. Abdel-salam Nabila M. Ghazy Shaimaa M. Sallam Mohamed M. Radwan Amira S. Wanas Mahmoud A. ElSohly 《Natural product research》2018,32(6):702-706
Alcea rosea L. is widely cultivated in gardens of Egypt as an ornamental plant and it has a great history of folkloric medicinal uses. In the present work, phytochemical investigation of the alcoholic extract of the flowers of A. rosea L. led to the isolation of six flavonoids (1–6). Dihydrokaempferol-4′-O-β-d-glucopyranoside (1), dihydrokaempferol (2), kaempferol-3-O-[6″-(E-coumaroyl)]-β-d-glucopyranoside (3), kaempferol-3-O-β-d-glucopyranoside (4), Apigenin (5) and kaempferol-3-O-α-l-rhamnopyranosyl-(1′″→6″)-β-d-glucopyranoside (6). Four of the isolated compounds were evaluated for their antioxidant, immunostimulant and cytotoxic activities against HepG-2 cell line. Compound (3) showed potent cytotoxic activity against HepG-2 cell line with high selectivity towards hepatocellular carcinoma in vitro (with IC50 = 3.8 μg/mL). Compounds 1 and 2 exhibited significant antioxidant activity and compound 4 showed a significant immune stimulant activity. Compound 1 is isolated for the first time from genus Alcea and this is the first report for its biological investigation. 相似文献
112.
On perfect simple-injective rings 总被引:4,自引:0,他引:4
Harada calls a ring right simple-injective if every -homomorphism with simple image from a right ideal of to is given by left multiplication by an element of . In this paper we show that every left perfect, left and right simple-injective ring is quasi-Frobenius, extending a well known result of Osofsky on self-injective rings. It is also shown that if is left perfect and right simple-injective, then is quasi-Frobenius if and only if the second socle of is countably generated as a left -module, extending many recent results on self-injective rings. Examples are given to show that our results are non-trivial extensions of those on self-injective rings.
113.
Yang G Amro NA Starkewolfe ZB Liu GY 《Langmuir : the ACS journal of surfaces and colloids》2004,20(10):3995-4003
A molecular-level approach is developed to prevent or inhibit the degradation processes of alkanethiol self-assembled monolayers (SAMs). Previous studies revealed two degradation pathways: direct desorption and oxidation-desorption. By use of scanning tunneling microscopy (STM) and atomic force microscopy (AFM), in situ and time-dependent imaging reveals and confirms that degradations of alkanethiol SAMs on gold mainly initiate at defect sites, such as domain boundaries and vacancy islands, and then propagate into the ordered domains. Our approach targets at attaching small molecules with preferred adhesion to the defects. The best candidates are aqueous media containing a small amount of amphiphilic surfactant molecules, such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO). High-resolution studies demonstrate that DMSO and DMF molecules attach to SAM surfaces and more favorably at defect sites, forming relatively stable adsorbates. This attachment increases the activation energy sufficiently to inhibit both degradation pathways. The robustness of this approach has been investigated as a function of surfactant concentration, solution temperature, and the stirring condition. Molecular-level mechanisms and energetics for degradation inhibition of SAMs are also discussed in detail. 相似文献
114.
Joseph A. Connor Colin Overton Nabil El Murr 《Journal of organometallic chemistry》1984,277(2):277-284
Electronic absorption spectra of cis-[Mo(CO)4(n,n′-X2-bipy)] (n = 4, X = NMe2, NH2, OMe, CMe3, Me, H, Ph, CH:CHPh, CO2H, Cl, CO2Me, NO; n=5, X = Me, CO2H) have been measured at ambient temperature in a variety of solvents of different polarity. Emission spectra from glasses containing the complexes at 77 K have also been measured. The influence of the substituent X on the spectroscopic properties is correlated with the Hammett parameters, σp (X) and σp+ (X). The effect of solvent is correlated with the Taft-Kamlet parameter, π★, indicating charge redistribution along the permanent dipole axis of the complex. The oxidation and reduction potentials in solution are simply related to the electronic effect of the substituent group, X, and are relatively independent of the solvent. The influence of the metal on these properties is not significant. 相似文献
115.
The thionation properties of 2,4-bismethylthio-1,3,2,4-dithiadiphosphetane 2,4-disulfide, , 2,4-bis(4-phen-oxyphenyl)-1,3,2,4-dithiaphosphetan is that , and thionate most amides and lactams In THF at room temperature (reaction time 5 min) to give the corresponding thionated compounds. Imides are easily thionated by , and In DME at 60 °C. The reactions of with amides, imides and most lactams are run at 60°C to give good yields of the corresponding thionated compounds. 相似文献
116.
Manal F. Abou Taleb Samia E. Abdel-Aal Nabil A. El-Kelesh El-Sayed A. Hegazy 《European Polymer Journal》2007,43(2):468-477
Adsorption and controlled release of Chlortetracycline HCl to and from multifunctional polymeric materials (HEMA/MAA) hydrogels were investigated. P(HEMA/MAA) hydrogels were synthesized by gamma radiation-induced copolymerization of 2-hydroxyethylmethacrylate (HEMA) and methacrylic acid (MAA) in aqueous solution. The influence of copolymer composition and pH value of the surrounding medium on the type of water diffusion into the glassy polymer were discussed. Drug, Chlortetracycline HCl containing hydrogels, with different drug concentration to polymer ratios, was loaded by direct adsorption method. The influence of MAA content in the gel on the adsorption capacities of hydrogel was studied. Chlortetracycline HCl adsorption capacity of hydrogels was found to increase from 8 to 138 mg Chlortetracycline HCl per gram dry gel with increasing amount of MAA in the gel system and drug concentration. The effect of pH on the releasing behavior of Chlortetracycline HCl from gel matrix was investigated. In vitro drug release studies in different buffer solutions show that the basic parameters affecting the drug release behavior of hydrogel are the pH of the solution and MAA content of hydrogel. 相似文献
117.
4H,5H-6-Phenyl (1a) and 6-p-phenoxyphenyl (1b) pyridazin-3(2H)-ones were reacted with aromatic aldehydes to give 4-arylmethylpyridazm-3(2H)-ones (2a-g), Oxidation of (2a-g) with various oxidising agents (selenium dioxide in ethanol or chromium trioxide in acetic acid) gave 4-aroyl-6-arylpyridazin-3(2H)-ones (3a-g). Chlorination of (3a-g) with phosphorous oxychloride afforded 4-aroyl-6-aryl-3-chloropyridazine (4a-g). 1H-3-Aryl-5-phenylpyrazolo[3,4-c]pyridazines (5a-d) were obtained by heating (4a-d) with excess hydrazine hydrate. Hydroxyamination of (3e-g) with iydroxylamine gave aryl-4(6-p-phenoxyphenyl-2,3-dihydro-3-oxo)pyridazinyl oxime (6a-c). Silylation of oximes (6b & 6c) gave (7a & 7b) as acyclic compound instead of the expected seven - membered - ring compound (8). 相似文献
118.
The kinetics of oxidation of cis-[CrIII(ox)2(H2O)2]– (ox = C2O4
2–) by IO4
– showed a first-order dependence on the initial CrIII complex concentration in the presence of a vast excess of [IO4
–]. The dependence of the pseudo-first-order rate constant on [IO4
–] is complex and is consistent with the formation of a precursor complex. It is proposed that this complex is formed through the coordination of the two carbonyl oxygens of the ox ligand with the IO4
– ion, forming a cyclic intermediate. The kinetics are consistent with the hydroxo form of the CrIII complex being the reactive species, whereas the aqua species forms an unreactive complex. 相似文献
119.
A.-Mohsen M. E. Omar Nabil H. Eshba Hamida M. Aboushleib 《Journal of heterocyclic chemistry》1986,23(6):1731-1735
A series of 3-(N-substituted thiocarbamoyl)hydrazino-1,2,4-triazino[5,6-b]indole derivatives 3–22 has been synthesized and evaluated for in vitro antimicrobial activity. Although some of the products displayed significant activity against Staphylococcus aureus, Escherichia coli and Candida albicans, their bactericidal and bacterostatic potencies were lower than that of penicillin G. The structure of the products was assigned upon the basis of their infrared, 1H-nmr and 13C-nmr spectra. 相似文献
120.
Cosimo Altomare Pierre-Alain Carrupt Nabil El Tayar Bernard Testa Toshiharu Nagatsu 《Helvetica chimica acta》1991,74(2):290-296
A number of isomers and analogs of the neurotoxin 1-methyl-4-phenylpyridinium (MPP+) were examined for their lipophilic behavior. Their partition coefficients in the 1-octanol/H2O system were measured by centrifugal partition chromatography (CPC), which, being much faster and markedly more precise than the classical shake-flask method, proved a very promising alternative for assessing lipophilicity. A smaller-than-expected lipophilicity was shown by the ortho-isomer of MPP+ (M2PP+) and is explained in terms of electronic effects and rigidity, as revealed by UV and NMR spectroscopy, and conformational analysis. Implications of lipophilicity in modulating the in vivo dopaminergic neurotoxicity of the examined compounds are also discussed. 相似文献