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1.
BinaS. Siddiqui M.Nadeem Kardar S.Tariq Ali Shazia Khan 《Helvetica chimica acta》2003,86(6):2164-2169
A new obtusafuran derivative, lawsonicin ( 1 ), and a new naphthaquinone, lawsonadeem ( 2 ), along with a known constituent, vomifoliol ( 3 ), were isolated from the aerial parts of Lawsonia alba and characterized by chemical transformation and spectroscopic experiments, including 2D‐NMR techniques. 相似文献
2.
Ahmad VU Khan A Farooq U Kousar F Khan SS Nawaz SA Abbasi MA Choudhary MI 《Chemical & pharmaceutical bulletin》2005,53(4):378-381
Three new tricyclic cis-clerodane type diterpenoids trivially named as limbatolide A (1), limbatolide B (2) and limbatolide C (3) have been isolated from the roots of Otostegia limbata along with two known compounds; oleanic acid and beta-sitosterol. The structure elucidation of the new compounds was based primarily on two-dimensional (2D) NMR techniques. Compounds 1-3 displayed inhibitory potential in a concentration-dependent manner against acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BChE; EC 3.1.1.8) enzymes, respectively. 相似文献
3.
Ahmad VU Zubair M Athar Abbasi M Abid Rashid M Rasool N Nahar Khan S Iqbal Choudhary M Kousar F 《Magnetic resonance in chemistry : MRC》2005,43(6):486-488
The investigation of the chemical constituents of Symplocos racemosa Roxb led to the isolation of two new glycosides, symcomoside A (1) and symcomoside B (2), together with one known glycoside, tortoside C (3), which is reported for the first time from this plant. The structures of the new compounds were determined by 1D and 2D homonuclear and heteronuclear NMR spectroscopy, from chemical evidence and by comparison with published data for closely related compounds. Symcomoside B (2) showed potent inhibitory activity against alpha-glucosidase in a concentration-dependent fashion with an IC50 value of 0.733 +/- 0.033 mM whereas symcomoside A (1) showed very weak inhibitory activity against alpha-glucosidase (9.90% in 0.70 mM). 相似文献
4.
A new crystal-engineering motif has been developed where a ditopic receptor 1 shows a novel syn-syn hydrogen-bonded polymeric supramolecular complex (Fig. 4b) (instead of a 1:1 dimeric syn-syn or polymeric syn-anti complex) giving rise to a hydrogen-bonded stair-like polymeric ribbon structure between the binding groups of the receptor pyridine amide and the carboxyl groups of the guest substrate. 相似文献
5.
Acta Mathematica Sinica, English Series - In this research article, we shall give some reverse Arithmetic-Geometric mean inequalities for unital positive linear maps on Hilbert space operators... 相似文献
6.
Marimganti S Yasmeen S Fischer D Maier ME 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6687-6700
The synthesis of the omega-amino acid 4 is described utilizing a two-dimensional synthesis strategy combined with an enzymatic differentiation of homotopic ester groups. The amino acid 4 features two non-bonded interactions that result in conformational constraints on a cyclic construct. This amino acid was incorporated into the four macrolactams 17, 22, 31, and 37. The ring in 17 and 22 is 18-membered, whereas 31 and 37 have a 19-membered ring. The pairs with the same ring size differ in a N-methyl group. For the larger macrolactams (31 and 37) conformational analysis showed that the macrocyclic rings are somewhat more rigid than in the natural lead, the depsipeptide jasplakinolide. Nevertheless, their conformations are comparable to the natural product. There are no intramolecular hydrogen bonds, neither is the cis-rotamer populated in the N-methyl compound 37. Due to the increased flexibility of the smaller macrolactams 17 and 22 and signal overlap, a distinct solution structure could not be obtained for these compounds. The amino acid 4 should be useful for restricting the conformation of other small peptides. 相似文献
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8.
Asma Hayat Shazia Bashir Muahmamd Shahid Rafique Mahreen Akram Khaliq Mahmood Saman Iqbal Asadullah Dawood Arooj 《Optics and Spectroscopy》2016,120(1):1-8
The optical characteristics of biological tissues sampled from the anterior abdominal wall of laboratory rats are for the first time experimentally studied in a wide wavelength range (350-2500 nm). The experiments have been performed in vitro using a LAMBDA 950 (PerkinElmer, United States) spectrophotometer. Inverse Monte Carlo simulation is used to restore the spectral dependences for scattering and absorption coefficients, as well as the scattering anisotropy factor for biological tissue based on the recorded spectra of diffuse reflection and total and collimated transmissions. 相似文献
9.
Shazia Iqbal Maria A. Khan Zulqarnain Ansari Almas Jabeen Aisha Faheem Saba Fazal-Ur-Rehman 《合成通讯》2013,43(18):2330-2341
AbstractCarbazole analogs 3 and 4 and a new library of bicarbazole-linked triazoles 6–11 were prepared via new synthetic methodology. Metal-catalyzed oxidative coupling reaction was utilized for the synthesis of bicarbazole acetylene 4 and different metals (Zn+2, Co+2, Fe+3, Ni+2, Cu+2, Mn+2) as catalyst were screened. Only Fe-catalyzed reaction was found to be excellent and gave homocoupled product 4. Cu-catalyzed 1,3-dipolar cycloaddition was also utilized to install triazole moiety for the synthesis of hybrid molecules 6–11. Based on reported anti-inflammatory activity of carbazole and triazole scaffolds, all compounds were screened for their reactive oxygen species (ROS) inhibitory potential. Results from these studies revealed triazole 9 as most active compound (IC50 value of 7.6?±?0.1?µg/mL on human whole blood and 2.7?±?0.09?µg/mL on isolated neutrophils) using ibuprofen as a standard. Therefore, class described herein can serve as attractive structural element for further studies on ROS inhibition. 相似文献
10.
Formation of the complex of ethyl viologen in its cationic (Ev+?) and neutral (Ev°) forms with β-cyclodextrin (β-CD) was investigated by means of voltammetric technique in buffer solution of pH 7.00. The number of βCD (n or m) per viologen species (Ev+?) or (Ev°), bonding equilibrium constants as well as bonding rate constants was calculated. The calculated values of $K_{\text{eq}}^{(1)}$ and $K_{\text{eq}}^{ ( 2)}$ (pertaining to the bonding of Ev+? and Ev° with βCD) are 13.6 M–n and 2.1 × 103 M?m , respectively, whereas the calculated values of n and m are 0.54 and 1.25, respectively. The bimolecular rate constant for the Ev°?βCD inclusion complex formation is 3.03 × 103 M?1s?1. These results are supported by the simulation of the experimental cyclic voltammograms. This study also highlights the significance of the proposed electrochemical method as compared to earlier studies on viologen-Cyclodextrin systems. 相似文献