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811.
812.
Mirza SP Raju NP Vairamani M 《Journal of the American Society for Mass Spectrometry》2004,15(3):431-435
The kinetic method, which is known to be simple, fast and precise, is used for the measurement of proton affinity values of fifteen selected matrix-assisted laser desorption/ionization matrices under electrospray ionization conditions. The stabilization of [M - H](-)/[M + Matrix - H](-) ions for beta-cyclodextrin in negative ion mode has been rationalized based on the proton affinity values of the matrices. 相似文献
813.
Gheevarghese Raju Sunaina Singh Andrew C. Mutter Bernard H. Everson Jose F. Cerda Ronald L. Koder 《Tetrahedron letters》2014
Safranines hold great promise as artificial flavin-like electron transfer cofactors with tunable properties. We have previously reported the stepwise synthesis of a safranine analogue, p-methoxy safranine. We now report an improved synthetic pathway which enables the synthesis of safranine analogues containing electron donating phenyl substituents. Low potential safranine analogues were synthesized that extend the range of two electron midpoint reduction potentials to 249 mV, or 11.4 kcal/mol. NMR analysis of the safranine series demonstrates that the 15N chemical shift at the N(5) position correlates with the two-electron reduction midpoint potential. 相似文献
814.
The present communication deals with the synthesis of 1,3,4‐oxadiazole‐2‐thiol derivatives containing cyclic secondary amines such as morpholine, N‐methyl piperizine, and piperizine. The structural elucidation is based on the spectral data (IR, 1H NMR, and 13C NMR) .The newly synthesized compounds were then tested for their antimicrobial activity against a representative panel of micro‐organisms such as Bacillus subtilis, Escherichia coli and Candida albicans by using ciprofloxacin and fluconazole as reference drugs for bacteria and fungi, respectively. These synthesized compounds showed moderate to potential antibacterial and antifungal activity in the range of 6–50 μM against the selected bacteria and 12–50 μM against the most common fungi, respectively. 相似文献
815.
Distribution study of cisplatin in rat kidney and liver cancer tissues by using liquid chromatography electrospray ionization tandem mass spectrometry 下载免费PDF全文
Raju Bandu Hyun Soo Ahn Joon Won Lee Yong Woo Kim Seon Hee Choi Hak Jin Kim Kwang Pyo Kim 《Journal of mass spectrometry : JMS》2015,50(6):844-853
A sensitive and rapid liquid chromatography positive ion electrospray ionization tandem mass spectrometric (LC/ESI‐MS/MS) method has been developed and validated for the quantitative determination and distribution of cisplatin (CP) in kidney and liver tissues after intravenous administration of drug to adult male Sprague Dawley rats. Oxaliplatin (OXP) was used as an internal standard. The tissue samples were homogenized and extracted using conventional liquid–liquid extraction method with phosphate buffer containing ethyl acetate and then subjected to LC‐MS analysis. The chromatographic separation was achieved on an Agilent ZORBAX SB C‐18 column (50 × 2.1 mm, 1.8 µm) using the mobile phase consisting of 0.1% formic acid in water (Solvent A) : methanol (Solvent B) (40 : 60; v/v) in an isocratic elution followed by detection with positive ion electrospray ionization tandem mass spectrometry using the transitions of m/z 301 > 265 for CP and m/z 398 > 310 for OXP in multiple reaction monitoring mode. The calibration curve was linear in the range of 5.0–7000 and 10.0–6000 ng/ml for kidney and liver tissue homogenates, respectively. The method revealed good performances in terms of within‐batch, between‐batch precision (1.31–5.70%) and accuracy (97.0–102.24%) for CP in both kidney and liver tissue homogenates including lower and upper limits of quantification. The recoveries from spiked control samples were >81.0% and >87.0 % for CP and OXP, respectively. Matrix effect was found to be negligible, and the stability data were within the acceptable limits. Further, the validated LC/ES‐MS/MS method was successfully applied to investigate the distribution of CP in kidney and liver tissues after intravenous administration of CP to male Sprague Dawley rats. The results showed that the higher amount of CP was distributed in kidney followed by liver, which indicated that CP mainly accumulated in kidney tissues and renal excretion might be a primary and main elimination route. This is the first research approach focused on the quantitative determination and distribution of CP in rat kidney and liver tissue homogenates by using LC/ESI‐MS/MS, which could provide essential information for further pharmacological and clinical studies of CP. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
816.
A sensitive,stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed for the quantitative estimation of nebivolol impurities in active pharmaceutical ingredient(API)and pharmaceutical formulation.Efficient chromatographic separation was achieved on an Acquity BEH C18 column(100 mm×2.1 mm,1.7μm)with mobile phase of a gradient mixture.The flow rate of the mobile phase was 0.18 mL/min with column temperature of 30℃and detection wavelength of 281 nm.The relative response factor values of(R*)-2-(benzylamino)-1-((S*)-6-fluorochroman-2-yl)ethanol((R*S*)NBV-1),(R)-1-((R)-6-fluorochroman-2-yl)-2-((S)-2-((S)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino)ethanol((RRSS)NBV-3),1-(chroman-2-yl)-2-(2-(6-fluorochroman-2-yl)-2-hydroxy ethyl amino)ethanol(monodesfluoro impurity),(S)-1-((R)-6-fluorochroman-2-yl)-2-((R)-2((S)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino)ethanol hydrochloride((RSRS)NBV-3)and(R*)-1-((S*)-6-fluorochroman-2-yl)-2-((S*)-2-((S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino)ethanol((R*S*S*S*)NBV-2)were 0.65,0.91,0.68,0.92 and 0.91 respectively.Nebivolol formulation sample was subjected to the stress conditions of acid,base,oxidative,hydrolytic,thermal,humidity and photolytic degradation.Nebivolol was found to degrade significantly under peroxide stress condition.The degradation products were well resolved from nebivolol and its impurities.The peak purity test results confirmed that the nebivolol peak was homogenous and pure in all stress samples and the mass balance was found to be more than 98%,thus proving the stability-indicating power of the method.The developed method was validated according to International Conference on Hormonization(ICH)guidelines with respect to specificity,linearity,limits of detection and quantification,accuracy,precision and robustness. 相似文献
817.
818.
N. V. Sita Mahalakshmi K. Premachand M. Ratna Raju 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(1):153-156
K-shell X-ray intensity ratios for some elements Sb, Cs, La, Ce, Pr, Nd, Sm, Gd, Dy and Ho have been measured experimentally. The elements were excited by 59.5 keV γ-ray from 100 mCi 241Am radioactive source. The characteristic K X-rays emitted by samples were detected by using a hyper pure germanium detector. The experimental results were compared with theoretical predictions reported by several authors. 相似文献
819.
Multiple Ambient Hydrolysis Deposition of Tin Oxide into Nanoporous Carbon To Give a Stable Anode for Lithium‐Ion Batteries 下载免费PDF全文
Dr. Vadivukarasi Raju Xingfeng Wang Dr. Wei Luo Prof. Xiulei Ji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7686-7691
A novel ambient hydrolysis deposition (AHD) methodology that employs sequential water adsorption followed by a hydrolysis reaction to infiltrate SnO2 nanoparticles into the nanopores of mesoporous carbon in a conformal and controllable manner is introduced. The empty space in the SnO2/C composites can be adjusted by varying the number of AHD cycles. An SnO2/C composite with an intermediate SnO2 loading exhibited an initial specific delithiation capacity of 1054 mAh g?1 as an anode for Li‐ion batteries. The capacity contribution from SnO2 in the composite electrode approaches the theoretical capacity of SnO2 (1494 mAh g?1) if both Sn alloying and SnO2 conversion reactions are considered to be reversible. The composite shows a specific capacity of 573 mAh g?1 after 300 cycles, that is, one of the most stable cycling performances for SnO2/mesoporous carbon composites. The results demonstrated the importance of well‐tuned empty space in nanostructured composites to accommodate expansion of the electrode active mass during alloying/dealloying and conversion reactions. 相似文献
820.
Cystobactamids: Myxobacterial Topoisomerase Inhibitors Exhibiting Potent Antibacterial Activity 下载免费PDF全文
Dr. Sascha Baumann Dr. Jennifer Herrmann Dr. Ritesh Raju Dipl.‐Ing. Heinrich Steinmetz Dr. Kathrin I. Mohr Dr. Stephan Hüttel Dr. Kirsten Harmrolfs Prof. Dr. Marc Stadler Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2014,53(52):14605-14609
The development of new antibiotics faces a severe crisis inter alia owing to a lack of innovative chemical scaffolds with activities against Gram‐negative and multiresistant pathogens. Herein, we report highly potent novel antibacterial compounds, the myxobacteria‐derived cystobactamids 1 – 3 , which were isolated from Cystobacter sp. and show minimum inhibitory concentrations in the low μg mL?1 range. We describe the isolation and structure elucidation of three congeners as well as the identification and annotation of their biosynthetic gene cluster. By studying the self‐resistance mechanism in the natural producer organism, the molecular targets were identified as bacterial type IIa topoisomerases. As quinolones are largely exhausted as a template for new type II topoisomerase inhibitors, the cystobactamids offer exciting alternatives to generate novel antibiotics using medicinal chemistry and biosynthetic engineering. 相似文献