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51.
Hasan H. Hasanov Ivaylo K. Ivanov 《Phosphorus, sulfur, and silicon and the related elements》2020,195(10):858-870
AbstractWe report herein a study on the competitive electrophilic cyclization of 5-(dimethoxyphosphoryl)-alka-3,4-dienoates involving 5-endo-trig and 6-endo-trig mode cyclizations. Reaction with electrophiles produces mixtures of the 2-(2-oxo-2,5-dihydro-1,2-oxaphosphol-5-yl)-alkanoates and (6-oxo-5,6-dihydro-2H-pyran-2-yl)-phosphonates by competitive electrophilic cyclization due to the participation of the neighboring phosphonate and carboxylate groups. 相似文献
52.
Tahira Foyzun Abdullah Al Mahmud Md. Salim Ahammed Md. Imran Nur Manik Md. Kamrul Hasan KM Monirul Islam Simin Sobnom Lopa Md. Yusuf Al-Amin Kushal Biswas Mst. Rejina Afrin AHM Khurshid Alam Golam Sadik 《Molecules (Basel, Switzerland)》2022,27(3)
Neurotoxicity is a serious health problem of patients chronically exposed to arsenic. There is no specific treatment of this problem. Oxidative stress has been implicated in the pathological process of neurotoxicity. Polyphenolics have proven antioxidant activity, thereby offering protection against oxidative stress. In this study, we have isolated the polyphenolics from Acacia nilotica and investigated its effect against arsenic-induced neurotoxicity and oxidative stress in mice. Acacia nilotica polyphenolics prepared from column chromatography of the crude methanol extract using diaion resin contained a phenolic content of 452.185 ± 7.879 mg gallic acid equivalent/gm of sample and flavonoid content of 200.075 ± 0.755 mg catechin equivalent/gm of sample. The polyphenolics exhibited potent antioxidant activity with respect to free radical scavenging ability, total antioxidant activity and inhibition of lipid peroxidation. Administration of arsenic in mice showed a reduction of acetylcholinesterase activity in the brain which was counteracted by Acacia nilotica polyphenolics. Similarly, elevation of lipid peroxidation and depletion of glutathione in the brain of mice was effectively restored to normal level by Acacia nilotica polyphenolics. Gallic acid methyl ester, catechin and catechin-7-gallate were identified in the polyphenolics as the major active compounds. These results suggest that Acacia nilotica polyphenolics due to its strong antioxidant potential might be effective in the management of arsenic induced neurotoxicity. 相似文献
53.
Halilibrahim Ciftci Belgin Sever Firdevs Ocak Nilüfer Bayrak Mahmut Yldz Hatice Yldrm Hasan DeMirci Hiroshi Tateishi Masami Otsuka Mikako Fujita Ama Fatih TuYuN 《Molecules (Basel, Switzerland)》2022,27(3)
Plants have paved the way for the attainment of molecules with a wide-range of biological activities. However, plant products occasionally show low biological activities and/or poor pharmacokinetic properties. In that case, development of their derivatives as drugs from the plant world has been actively performed. As plant products, plastoquinones (PQs) have been of high importance in anticancer drug design and discovery; we have previously evaluated and reported the potential cytotoxic effects of a series of PQ analogs. Among these analogs, PQ2, PQ3 and PQ10 were selected for National Cancer Institute (NCI) for in vitro screening of anticancer activity against a wide range of cancer cell lines. The apparent superior anticancer potency of PQ2 on the HCT-116 colorectal cancer cell line than that of PQ3 and PQ10 compared to other tested cell lines has encouraged us to perform further mechanistic studies to enlighten the mode of anti-colorectal cancer action of PQ2. For this purpose, its apoptotic effects on the HCT-116 cell line, DNA binding capacity and several crucial pharmacokinetic properties were investigated. Initially, MTT assay was conducted for PQ2 at different concentrations against HCT-116 cells. Results indicated that PQ2 exhibited significant cytotoxicity in HCT-116 cells with an IC50 value of 4.97 ± 1.93 μM compared to cisplatin (IC50 = 26.65 ± 7.85 μM). Moreover, apoptotic effects of PQ2 on HCT-116 cells were investigated by the annexin V/ethidium homodimer III staining method and PQ2 significantly induced apoptosis in HCT-116 cells compared to cisplatin. Based on the potent DNA cleavage capacity of PQ2, molecular docking studies were conducted in the minor groove of the double helix of DNA and PQ2 presented a key hydrogen bonding through its methoxy moiety. Overall, both in vitro and in silico studies indicated that effective, orally bioavailable drug-like PQ2 attracted attention for colorectal cancer treatment. The most important point to emerge from this study is that appropriate derivatization of a plant product leads to unique biologically active compounds. 相似文献
54.
Aye Ünlü Kerem Teral Zübeyde Uurlu Aydn Ali A. Dnmez Hasan Soliman Yusufolu hsan al 《Molecules (Basel, Switzerland)》2022,27(3)
Polygala species are frequently used worldwide in the treatment of various diseases, such as inflammatory and autoimmune disorders as well as metabolic and neurodegenerative diseases, due to the large number of secondary metabolites they contain. The present study was performed on Polygala inexpectata, which is a narrow endemic species for the flora of Turkey, and resulted in the isolation of nine known compounds, 6,3′-disinapoyl-sucrose (1), 6-O-sinapoyl,3′-O-trimethoxy-cinnamoyl-sucrose (tenuifoliside C) (2), 3′-O-(O-methyl-feruloyl)-sucrose (3), 3′-O-(sinapoyl)-sucrose (4), 3′-O-trimethoxy-cinnamoyl-sucrose (glomeratose) (5), 3′-O-feruloyl-sucrose (sibiricose A5) (6), sinapyl alcohol 4-O-glucoside (syringin or eleutheroside B) (7), liriodendrin (8), and 7,4′-di-O-methylquercetin-3-O-β-rutinoside (ombuin 3-O-rutinoside or ombuoside) (9). The structures of the compounds were determined by the spectroscopic methods including 1D-NMR (1H NMR, 13C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC), and HRMS. The isolated compounds were shown in an in silico setting to be accommodated well within the inhibitor-binding pockets of myeloperoxidase and inducible nitric oxide synthase and anchored mainly through hydrogen-bonding interactions and π-effects. It is therefore plausible to suggest that the previously established anti-inflammatory properties of some Polygala-derived phytochemicals may be due, in part, to the modulation of pro-inflammatory enzyme activities. 相似文献
55.
中国剪纸的设计极具挑战性, 要求画面简洁、直观, 还需要表达特定的文化内涵, 且整张剪纸须整体连通。提出了一种基于图像的二维剪纸自动生成方法, 能够将任意数码照片自动转化为剪纸图形。首先,利用图像分割方法建立区域连接图; 接着, 基于该连接图对颜色、边界对比度和区域连通性进行数学建模, 并获得优化目标函数; 最后, 通过模拟退火算法求解目标方程, 自动生成保持图像内容的剪纸图形。还开发了连通性后处理和区域指定等用户交互工具, 允许用户在自动生成的剪纸图形中方便地加入个人设计。实验表明, 所生成的剪纸图形画面简洁、整体连通。 本方法在降低剪纸设计难度的同时还可满足个性化的设计需求, 有助于传播和传承我国的民间剪纸艺术。 相似文献
56.
57.
A conformational study of the biomolecules released from submicron- and micron-sized temperature-sensitive composite polymer
particles by decreasing the temperature from 40 to 25 °C was done with circular dichroism and the results were compared with
those of the native biomolecules. In almost all cases the biomolecules released retained their native conformational states.
Received: 10 April 2001 Accepted: 13 June 2001 相似文献
58.
Hasan M. Khan Shagufta Naz Safia Tabassum 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):225-229
Aqueous solution of crystal violet has been evaluated spectrophotometrically as a gamma-ray chemical dosimeter. The response
of the chemical dosimetric system has also been investigated under different environmental conditions, such as light and temperature.
In the present study the response has been measured at two wavelengths; 588 nm (λmax of the irradiated solution) and 500 nm. The response of the crystal violet dosimeter was linear in the dose range of 50–550 Gy
at pH 5.6 when absorption measurements were made at 588 and 500 nm. The response of the crystal violet dosimeter during post-irradiation
storage at room temperature in dark showed slight decrease in absorbance at 588 and 510 nm but the response was almost stable
at 460 nm. For higher doses, the change in the response was greater as compared to the low doses. Post-irradiation stability
during diffused sunlight showed significant decrease in the response for higher dose at 588 and 510 nm and slower decrease
in the response for lower dose at the above mentioned wavelengths. However the response was almost stable up to 97 days at
460 nm for higher and lower doses. At 4 °C, the decrease in the absorbance was slower at 588 and 510 nm while the response
was almost constant at 460 nm. At higher temperatures, such as 40 °C, the decrease in the absorbance was greater at 588 and
510 nm while at 460 nm the absorbance was almost constant for about 3 months. 相似文献
59.
Gas sensing is one of the most promising applications for graphene. Using molecular dynamics simulation method, adsorption isotherm of xenon (Xe) gas on defected and perfect graphene is studied in order to investigate sensing properties of graphene for Xe gas. In this method, first generation of Brenner many-body potential is used to simulate the interaction of carbon–carbon (C) atoms in graphene, and Lennard–Jones two-body potential is used to simulate interaction of Xe–Xe and Xe–C atoms. In the simulated systems, adsorption coverage, radial distribution function, heat of adsorption, binding energy and specific heat capacity at constant volume are calculated for several temperatures between 90 K and 130 K, and various pressures. It was found that both of the defected and perfect graphene could be introduced as very good candidates for adsorption of Xe gas. 相似文献
60.
Experimental results on the extrapolated ultimate enhancement factors of o-, m-, and p-xylene protons at 1.53 mT are obtained for MC800 asphalt solutions. The ultimate enhancement factors are found such as ?26.9, ?25.7, and ?11.7 for o-, m-, and p-xylene, respectively. These results show that the solvent proton Overhauser effect cannot reach the extrapolated enhancement of ?330 in the extreme narrowing case because of occurrence of small scalar interactions in addition to the dipole–dipole interactions between solvent protons and asphalt electrons. The ortho, meta, and para positions of the –CH3 group change the nature of the interactions. The nuclear magnetic resonance (NMR) signal enhancements exhibit a sensitive behavior depending on the chemical environment differing from isomer to isomer. The solvation or association of asphalt in xylene isomers at room temperature is revealed. Quantum chemical calculations for the xylene isomers with the electronic and optical properties; absorption wavelengths, excitation energy, atomic charges, dipole moment and frontier molecular orbital energies, molecular electrostatic potential; are carried out using the density functional theory (DFT) method (B3LYP) with the 6-311G(d,p) basis set by the standard Gaussian 09 software package program. The relative importance of scalar and translational dipolar interaction parameters determined in dynamic nuclear polarization experiments is explained by the electronic structure of HOMO–LUMO of the xylene isomers. 相似文献