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71.
Thomas P. A. Devasagayam Mayilvahanan Subramanian B. B. Singh R. Ramanathan Nagaratnam P. Das 《Journal of photochemistry and photobiology. B, Biology》1995,30(2-3):97-103
Flavonoids, the dominant colouring pigments of plants, as well as the related polyphenol tannic acid significantly inhibit single-strand breaks in plasmid pBR322 DNA induced by singlet molecular oxygen (1O2). This reactive species of oxygen was generated in an aqueous buffer system by the thermal dissociation of the endoperoxide of 3,3′-(1,4-naphthylene)dipropionate. Among the antioxidants examined, myricetin showed the highest protective ability, followed by tannic acid, (+) catechin, rutin, fisetin, luteolin and apigenin, when the inhibitory abilities were compared at 90 min after incubation. The protective abilities of these compounds were both time and concentration dependent. At equimolar concentrations (100 μM) the antioxidant effect of myricetin was better than that of other known antioxidants such as lipoate, -tocopherol and β-carotene. Data, when analysed in relation to the structures of various compounds, showed a rough correlation with protective abilities. Owing to the abundance of these compounds in our normal diet, they may play significant roles in preventing oxidative damage resulting from potentially deleterious 1O2. 相似文献
72.
Vinay Deepak HS Joy A Suryaprakash N Ramanathan KV 《Magnetic resonance in chemistry : MRC》2004,42(4):409-413
A novel method for assigning the resonances in the 13C NMR spectrum of a static liquid crystalline sample in its nematic phase is proposed. The method is based on the fact that the carbon chemical shifts in the isotropic phase and in the oriented phase under static and off-magic angle spinning (OMAS) conditions are uniquely related by the tensorial property of the CSA tensor, requiring just one OMAS spectrum and the assignment in the isotropic phase. A computational procedure is proposed to take into account deviations arising out of non-ideal experimental conditions and the assignments are made by identifying the minimum in the differences in the frequencies between calculated and experimental line positions. Practical implementation of the method has also been demonstrated in the case of the liquid crystal N-(4-ethoxybenzylidene)-4-n-butylaniline. 相似文献
73.
Prathibha T. Selvan B. Robert Hemalatha V. Suba M. Amutha Chandra Swaroop Shaji Dinu Vijay Soja K. Sundararajan K. Ramanathan N. 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2383-2391
Journal of Radioanalytical and Nuclear Chemistry - A spectrophotometric method, circumventing interference from F− ions, during estimation of Zr in U-Zr alloy fuel, has been developed.... 相似文献
74.
P. Judeinstein P. Berdagué J.-P. Bayle Neeraj Sinha K. V. Ramanathan 《Liquid crystals》2013,40(11):1691-1698
Short terminal polyoxyethylene chains may be introduced into mesogens containing lateral substituents such as two hexyloxy chains or a crown-ether fragment. These compounds have a large nematic range near room temperature and can dissolve large amounts of the salt LiBF4 without destroying the nematic arrangment. In the nematic phase, the ions are ordered and the quadrupolar splitting associated with these ions can allow this ordering to be monitored. Increasing the salt concentration does not seem to change the ordering of the individual ions. The 13C thermal evolution of the field-induced chemical shift in the oxyethylene (OE) units with or without salt does not show any real difference, indicating that the interaction between the ions and the mesogen is small. This means that there is very little change in conformation in the OE unit when adding salt to the mesogen. 相似文献
75.
Y. Nagendra Prasad V. Vinod Kumar S. Ramanathan 《Journal of Solid State Electrochemistry》2009,13(9):1351-1359
Anodic dissolution of copper in arginine and hydrogen peroxide-based medium suitable for chemical mechanical planarization
slurry formulation was investigated using electrochemical impedance spectroscopy. Potentiodynamic polarization and impedance
data were acquired for copper dissolving in hydrogen peroxide and arginine solution. Reaction mechanism analysis (RMA) was
employed to determine the mechanistic pathway of copper dissolution. RMA analysis indicates that a stable passivating film
does not form on the copper surface, and the direct dissolution of copper was also ruled out. A two-step mechanism involving
cupric oxide as an intermediate species is proposed. The data were also fit to an electrical equivalent circuit to obtain
insight into the variation of the parameters with the overpotential. The modeled data for the two-step mechanism captures
the essential features of the impedance spectra at various overpotentials. 相似文献
76.
77.
Suhanya Parthasarathy Surash Ramanathan Sabariah Ismail Mohd Ilham Adenan Sharif Mahsufi Mansor Vikneswaran Murugaiyah 《Analytical and bioanalytical chemistry》2010,397(5):2023-2030
A new solid phase extraction method for rapid high performance liquid chromatography–UV determination of mitragynine in plasma
has been developed. Optimal separation was achieved with an isocratic mobile phase consisting of acetonitrile–ammonium acetate
buffer, 50 mM at pH 5.0 (50:50, v/v). The method had limits of detection and quantification of 0.025 and 0.050 μg/mL, respectively.
The method was accurate and precise for the quantitative analysis of mitragynine in human and rat plasma with within-day and
between-day accuracies between 84.0 and 109.6%, and their precision values were between 1.7 and 16.8%. Additional advantages
over known methods are related to the solid phase extraction technique for sample preparation which yields a clean chromatogram,
a short total analysis time, requires a smaller amount of plasma samples and has good assay sensitivity for bioanalytical
application. The method was successfully applied in pharmacokinetic and stability studies of mitragynine. In the present study,
mitragynine was found to be fairly stable during storage and sample preparation. The present study showed for the first time
the detailed pharmacokinetic profiles of mitragynine. Following intravenous administration, mitragynine demonstrated a biphasic
elimination from plasma. Oral absorption of the drug was slow, prolonged and was incomplete, with a calculated absolute oral
bioavailability value of 3.03%. The variations observed in previous pharmacokinetic studies after oral administration of mitragynine
could be attributed to its poor bioavailability rather than to the differences in assay method, metabolic saturation or mitragynine
dose. 相似文献
78.
The three-dimensional sponge-like mesoporous material TUD-1 is straightforward to prepare. Its synthesis can readily be modified to introduce metals into the framework of TUD-1, imparting many different catalytic activities. M-TUD-1 catalysts have proven to be very active, unlimited by diffusion and very stable. By combining two metals into one TUD-1 catalyst, synergy between Lewis and Br?nsted acid sites could be induced; incorporation of zeolites similarly gave rise to synergy. In addition to successful applications in redox-, acid- and photo-catalysis TUD-1 proved to be an excellent carrier material for catalysts, enabling new applications. TUD-1 was used as a contrast agent and drug delivery system, indicating that this material is but at the beginning of its potential applications. 相似文献
79.
Targeting ErbB family of receptors is an important therapeutic option, because of its essential role in the broad spectrum of human cancers, including non-small cell lung cancer (NSCLC). Therefore, in the present work, considerable effort has been made to develop an inhibitor against HER family proteins, by combining the use of pharmacophore modelling, docking scoring functions, and ADME property analysis. Initially, a five-point pharmacophore model was developed using known HER family inhibitors. The generated model was then used as a query to screen a total of 468,880 compounds of three databases namely ZINC, ASINEX, and DrugBank. Subsequently, docking analysis was carried out to obtain hit molecules that could inhibit the HER receptors. Further, analysis of GLIDE scores and ADME properties resulted in one hit namely BAS01025917 with higher glide scores, increased CNS involvement, and good pharmaceutically relevant properties than reference ligand, afatinib. Furthermore, the inhibitory activity of the lead compounds was validated by performing molecular dynamic simulations. Of note, BAS01025917 was found to possess scaffolds with a broad spectrum of antitumor activity. We believe that this novel hit molecule can be further exploited for the development of a pan-HER inhibitor with low toxicity and greater potential. 相似文献
80.