排序方式: 共有103条查询结果,搜索用时 15 毫秒
41.
H. M. Khan S. Tabassum M. S. Wahid 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(3):635-641
Dilute aqueous solution of cresol red has been evaluated spectrophotometrically as possible gamma rays dosimeter. A 0.10 mM
solution of cresol red was irradiated by gamma rays using a cobalt-60 radiation source. The absorbance spectra of the unirradiated
and irradiated solutions were recorded using double beam scanning spectrophotometer. The absorbance of the solution before
and after irradiation was measured at 434 nm (λmax) as well as at other wavelengths (415, 448 and 470 nm). Various parameters, such as Absorbance (A), ΔA, %A, -log A and log
Ao/Ai were plotted against radiation dose, in order to check the response of cresol red solution and its possible use as chemical
dosimeter. The response plots of A, ΔA, and %A versus absorbed dose showed that the solution can be used as a radiation dosimeter
in a dose range up to 0.82 kGy. Using response plots of -log A and log Ao/Ai, the useful dose range can be extended up to 1.65 kGy; which are useful dose ranges for food irradiation applications. Stability
studies of cresol red solution at different light and temperature conditions for pre- and post-irradiated storage of the dosimetric
solutions suggested that aqueous solution of cresol red is highly stable in dark, under fluorescence light and at room temperature
up to 150 days 相似文献
42.
Mrunal Jadhav Kaksha Sankhe Richie R. Bhandare Zehra Edis Samir Haj Bloukh Tabassum Asif Khan 《Molecules (Basel, Switzerland)》2021,26(17)
The past few decades have witnessed significant progress in anticancer drug discovery. Small molecules containing heterocyclic moieties have attracted considerable interest for designing new antitumor agents. Of these, the pyrimidine ring system is found in multitude of drug structures, and being the building unit of DNA and RNA makes it an attractive scaffold for the design and development of anticancer drugs. Currently, 22 pyrimidine-containing entities are approved for clinical use as anticancer drugs by the FDA. An exhaustive literature search indicates several publications and more than 59 patents from the year 2009 onwards on pyrimidine derivatives exhibiting potent antiproliferative activity. These pyrimidine derivatives exert their activity via diverse mechanisms, one of them being inhibition of protein kinases. Aurora kinase (AURK) and polo-like kinase (PLK) are protein kinases involved in the regulation of the cell cycle. Within the numerous pyrimidine-based small molecules developed as anticancer agents, this review focuses on the pyrimidine fused heterocyclic compounds modulating the AURK and PLK proteins in different phases of clinical trials as anticancer agents. This article aims to provide a comprehensive overview of synthetic strategies for the preparation of pyrimidine derivatives and their associated biological activity on AURK/PLK. It will also present an overview of the synthesis of the heterocyclic-2-aminopyrimidine, 4-aminopyrimidine and 2,4-diaminopyrimidine scaffolds, and one of the pharmacophores in AURK/PLK inhibitors is described systematically. 相似文献
43.
Irshad M. Ali Q. Iram F. Ahamad S. A. Saleem M. Saadia M. Batool M. Kanwal A. Tabassum S. 《Russian Journal of General Chemistry》2019,89(7):1519-1527
Russian Journal of General Chemistry - Synthesis of some new multi-functional analogues of 2′-hydroxy chalcone containing isoxazole and pyrazole functions were synthesized, and their... 相似文献
44.
Saiqa Jabeen Sahib Alam Maria Saleem Waqar Ahmad Rukhsana Bibi Farrukh S. Hamid Hamid U. Shah 《Arabian Journal of Chemistry》2019,12(8):2411-2417
The aim of the present study was to investigate the effect of withering timings (i.e. 0, 21, 22, 23 and 24 h) on the moisture, total free amino acids, ash, essential and toxic mineral element contents of tea (Camellia sinensis L.) leaves during black tea manufacturing. Moisture, ash, Na, P, Mg, Cu, Zn, Mn, Al, Ni and Pb contents were significantly (P < 0.05) affected by withering, whereas non-significant (P > 0.05) results were noted for total free amino acids, K, Fe and Cd contents. The highest moisture content (76.4%) was examined in fresh leaves that progressively decreased to 63.8% in 24 h withering. Total free amino acid contents gradually increased up to 23 h and then decreased. Ash, P, Cu, Zn and Mn contents showed an increasing trend with withering time. Conversely, significantly lowered amounts of Na (162.5 mg/kg) and Mg (803 mg/kg) were recorded in tea leaves after 24 h withering. Among the toxic elements, Al, Ni and Pb contents were progressively increased over withering time. It was concluded that tea is a potential source of essential chemical constituents and during processing proper care should be taken to produce high quality black tea. 相似文献
45.
Rukhsana Kouser G Tasneem Muhammad Saleem Shahzad S Sardar Amjad Ali M H Nasim M Salahuddin 《中国物理 B》2017,26(7):75201-075201
We present the preliminary results of our code OPAQS(opacity calculation using quantum statistical model) that is based on the self consistent Hartree-Fock-Slater model for the average atom. The code is capable of performing robust calculations of average charge state, frequency-dependent and mean opacities. The accuracy of the atomic model is verified by comparing the calculations of average charge state with various published results. The monochromatic opacities for iron computed at different sets of temperatures and densities are compared with LEDCOP. The Rosseland and Planck opacities for iron and aluminum are validated with some state-of-the-art codes. The results are in good agreement with the published data. 相似文献
46.
Sabiha Parveen Mohd. Sajid Ali Hamad A. Al-Lohedan Sartaj Tabassum 《Molecules (Basel, Switzerland)》2021,26(21)
Lysozyme is often used as a model protein to study interaction with drug molecules and to understand biological processes which help in illuminating the therapeutic effectiveness of the drug. In the present work, in vitro interaction studies of 1-{(2-hydroxyethyl)amino}-2-amino-1,2-dideoxy-d-glucose triphenyl tin (IV) (GATPT) complex with lysozyme were carried out by employing various biophysical methods such as absorption, fluorescence, and circular dichroism (CD) spectroscopies. The experimental results revealed efficient binding affinity of GATPT with lysozyme with intrinsic binding (Kb) and binding constant (K) values in the order of 105 M−1. The number of binding sites and thermodynamic parameters ΔG, ΔH, and ΔS at four different temperatures were also calculated and the interaction of GATPT with lysozyme was found to be enthalpy and entropy driven. The CD spectra revealed alterations in the population of α–helical content within the secondary structure of lysozyme in presence of GATPT complex. The morphological analysis of the complex with lysozyme and lysozyme-DNA condensates was carried out by employing confocal and SEM studies. Furthermore, the molecular docking studies confirmed the interaction of GATPT within the larger hydrophobic pocket of the lysozyme via several non-covalent interactions. 相似文献
47.
Anjum Khursheed Saeed Ahmad Kashif-ur-Rehman Khan Muhammad Imran Tousif Hanan Y. Aati Chitchamai Ovatlarnporn Huma Rao Umair Khurshid Bilal Ahmad Ghalloo Sobia Tabassum Abdul Basit 《Molecules (Basel, Switzerland)》2022,27(13)
Roots of Rondeletia odorata are a rich source of phytochemicals with high antioxidant potential and thus may possess health benefits. This study used the LC-MS technique to identify phytoconstituents in R. odorata roots extract/fractions. Results revealed that n-butanol fraction and ethanolic extract contained total phenolic and flavonoid contents with values of 155.64 ± 0.66 mgGAE/g DE and 194.94 ± 0.98 mgQE/g DE, respectively. Significant potential of antioxidants was observed by DPPH, CUPRAC and FRAP methods while the ABTS method showed moderate antioxidant potential. Maximum % inhibition for urease, tyrosinase and carbonic anhydrase was shown by ethanolic extract (73.39 ± 1.11%), n-butanol soluble fraction (80.26 ± 1.59%) and ethyl acetate soluble fraction (76.50 ± 0.67%) which were comparable with thiourea (standard) (98.07 ± 0.74%), kojic acid (standard) (98.59 ± 0.92%) and acetazolamide (standard) (95.51 ± 1.29%), respectively, while all other extract/fractions showed moderate inhibition activity against these three enzymes. Hemolytic activity was also observed to range from 18.80 ± 0.42 to 3.48 ± 0.69% using the standard (triton X-100) method. In total, 28 and 20 compounds were identified tentatively by LC-MS analysis of ethanolic extract and n-butanol soluble fraction, respectively. Furthermore, molecular docking was undertaken for major compounds identified by LC-MS for determining binding affinity between enzymes (urease, tyrosinase and carbonic anhydrase) and ligands. It was concluded that active phytochemicals were present in roots of R. odorata with potential for multiple pharmacological applications and as a latent source of pharmaceutically important compounds. This should be further explored to isolate important constituents that could be used in treating different diseases. 相似文献
48.
Aminopropylated PEG as a novel,eco‐friendly and biodegradable basic catalyst for bis‐Michael addition to α,β‐unsaturated ketones under solvent‐free conditions 下载免费PDF全文
A solvent‐free and highly efficient protocol has been developed for the synthesis of novel bis‐Michael addition products ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , 3o ) using aminopropylated PEG‐6000 (NH2‐PEG) as a biodegradable and recyclable catalyst in excellent yields under solvent‐free conditions. Other remarkable features of this environmentally benign protocol are shorter reaction time, tolerance of a wide range of C―H‐activated acids, high yield of products, and simple experimental and work‐up procedure as compared to conventional methods. The NH2‐PEG catalyst is characterized by using FT‐IR, powder XRD and scanning electron microscopy–energy dispersion X‐ray spectrometric analyses. The catalyst can be recycled several times without significant loss of its catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
49.
A new boroderivative of ciprofloxacin and its CuII complex has been synthesized and characterized by elemental analysis, i.r., e.p.r., u.v.–vis., n.m.r. spectroscopy. Molar conductance measurements show that the complex is ionic. E.p.r. values and electronic spectral data suggest that it possesses square planar geometry. The reaction kinetics of the ligand K[C34H36N6O6F2B] and its CuII complex with calf thymus DNA (CTDNA) has been monitored spectrophotometrically in aqueous media. The K
obs value has been calculated under pseudo-first order conditions and it has been observed that the CuII complex is a more efficient DNA inhibitor than the free borate of ciprofloxacin. The redox behavior of the CuII complex in the presence and in the absence of CTDNA in aqueous solution has been investigated by cyclic voltammetry. The cyclic voltammogram of the CuII complex exhibits one quasireversible redox wave for a one-electron transfer corresponding to CuII/CuI redox couple with E
1/2 values –0.613 and –0.649 V respectively. On interaction with CTDNA, the CuII complex exhibits a shift in E
1/2 values corresponding to 0.013 and 0.035 V respectively. 相似文献
50.
The new homodinuclear complexes 1–4 of the type [LMII
2Cl2], heterotrinuclear complexes 5 and 6 of the type [LMII
2SnIVCl6] where M = CuII, MnII, CoII, NiII and CuII and NiII, respectively have been synthesized and characterized by elemental analysis and various spectroscopic techniques. The homodinuclear
complexes possess two different environments (N2 and N2O2donor sets) for holding the metal ions. The metal ion in N2 set exhibits square planar geometry with two chloride ions in the inner sphere but rhombic structure is found in tetradentate
N2O2 Schiff base cavity while in heterotrinuclear complexes SnIV atom is in the octahedral environment. The interaction of complexes 1 and 5 with calf thymus DNA was carried out by absorption spectroscopy and cyclic voltammetry. The intrinsic binding constants (K
b
) of complex 1 and 5 were determined as 3.2 × 103 M−1 and 9.6 × 103 M−1, respectively suggesting that complex 5 binds more strongly to CT-DNA than complex 1. Fluorescence studies along with viscosity measurements have also been checked to authenticate the binding of metal complexes
with DNA. 相似文献