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71.
Bharathi DV Naidu A Jagadeesh B Laxmi KN Laxmi PR Reddy PR Mullangi R 《Biomedical chromatography : BMC》2008,22(6):645-653
A highly sensitive and specific LC-MS/MS method has been developed and validated for the estimation of zafirlukast (ZFK) with 500 microL human plasma using valdecoxib as an internal standard (IS). The API-4,000 LC-MS/MS was operated under multiple reaction-monitoring mode using the electrospray ionization technique. The assay procedure involved extraction of ZFK and IS from human plasma with ethyl acetate. The resolution of peaks was achieved with 10 mm ammonium acetate (pH 6.4):acetonitrile (20:80, v/v) on a Hypersil BDS C(18) column. The total chromatographic run time was 2.0 min and the elution of ZFK and IS occurred at approximately 1.11 and 1.58 min, respectively. The MS/MS ion transitions monitored were 574.2 --> 462.1 for ZFK and 313.3 --> 118.1 for IS. The method was proved to be accurate and precise at a linearity range of 0.15-600 ng/mL with a correlation coefficient (r) of >or=0.999. The method was rugged with 0.15 ng/mL as lower limit of quantitation. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 20 mg ZFK tablet. 相似文献
72.
Ch. Mohan B. Hari Babu C. Naga Raju C. Suresh Reddy V. Janardhan Reddy 《Journal of heterocyclic chemistry》2008,45(5):1337-1341
73.
Rekulapally Sriram Chebolu Naga Sesha Sai Pavan Kumar Nerella Raghunandan Vadla Ramesh 《合成通讯》2013,43(23):3419-3428
Abstract A simple and efficient method is described for the oxidation of 7-azaindoles and indoles to 7-azaisatins and isatins using pyridinium chlorochromate–silica gel (PCC-SiO2) with the aid of Lewis acid catalyst aluminium chloride (AlCl3) in dichloroethane. Simplicity of the reaction conditions, easy workup procedure, and good yields are the key features of this protocol. 相似文献
74.
Fast and safe: accelerated gradient methods with optimality certificates and underestimate sequences
Jahani Majid Gudapati Naga Venkata C. Ma Chenxin Tappenden Rachael Takáč Martin 《Computational Optimization and Applications》2021,79(2):369-404
Computational Optimization and Applications - In this work we introduce the concept of an Underestimate Sequence (UES), which is motivated by Nesterov’s estimate sequence. Our definition of a... 相似文献
75.
In this paper we propose preconditioners for spectral element methods for elliptic and parabolic problems. These preconditioners are constructed using separation of variables and are easy to invert. Moreover they are spectrally equivalent to the quadratic forms which they are used to approximate. 相似文献
76.
Kodakandla Venkata Syamasundar Guvvala Vinodh Kalavagunta Venkata Naga Satya Srinivas Bogineni Srinivasulu 《Helvetica chimica acta》2012,95(4):643-646
Chemical examination of the MeOH extract of Plectranthus bishopianus Benth ., a rare and endangered plant, resulted in isolation of a new abietane diterpene, 6β‐hydroxy‐7α‐methoxyroyleanone ( 1 ), along with two more diterpenoids, 6,7‐dehydroroyleanone, and 6β,7α‐dihydroxyroyleanone, a triterpene oleanolic acid, and two sterols, β‐sistosterol and stigmasterol. The structures of the isolated compounds were elucidated on the basis of spectroscopic data and also by comparison with authentic samples. 相似文献
77.
A simple spectrophotometric method for the determination of propoxur, a widely used insecticide, in various environmental samples and pesticide formulations is described. The method is based on the coupling of the hydrolysis product of propoxur with diazotized 3-aminopyridine in an alkaline medium, to form an azo-dye which has a maximum absorbance at 463 nm. Beer's law is obeyed over the concentration range of 0.05 to 1.2 microg ml(-1) of propoxur. The molar absorptivity and Sandell's sensitivity are found to be 3.10 x 10(4) l mol(-1) cm(-1) and 0.007 microg cm(-2), respectively. The important analytical parameters and optimum reaction conditions were evaluated. The method is free from the interference of other commonly used pesticides and inorganic metal ions. 相似文献
78.
Radha Krishna Singamsetty Satish Kumar Vujjini Nagaraju Manne Brahmeshwara Rao Mandava Venkata Naga Vurimidi Himabindu Apurba Battacharya 《合成通讯》2013,43(24):4452-4459
A noninfringing synthesis of simvastatin 1, starting from lovastatin 2, is presented. This synthesis features the protection of the free hydroxyl group of the lovastatin with 3,4-dihydro-2H-pyran (DHP) and opening of the lactone ring with n-BuNH2 to afford amide 4 as a key intermediate. 相似文献
79.
A facile one-pot synthesis of pyrrolidinyl-spirooxindole grafted 3-nitrochromanes has been accomplished by 1,3-dipolar cycloaddition (1,3-DC) reaction of 3-nitrochromenes with azomethine ylides generated in situ from isatin and secondary amino acids. The regio- and stereochemical outcome of the cycloaddition reaction was ascertained by X-ray crystallographic analysis. 相似文献
80.
P. Haranath V. Sreedhar Kumar C. Suresh Reddy C. Naga Raju C. Devendranath Reddy 《合成通讯》2013,43(10):1697-1708
6‐Substituted‐dibenzo[d, f][1,3,2]dioxaposphepin‐6‐oxides, sulfides, and selenides (5a–i, 6a–d, and 7a–d) were synthesized by reacting 2,2′‐biphenol (1) with phosphorus tribromide in the presence of triethylamine at 0–30°C and subsequent reaction of the monobromide (2) with different Grignard reagents (3) at room temperature. The products (4) were converted to corresponding oxides, sulfides, and selenides (5a–i, 6a–d, and 7a–d) by oxidation with H2O2 at room temperature and refluxing with sulfur and selenium respectively. The chemical structures of all the products were confirmed by analytical, IR, NMR (1H, 13C, and 31P), and mass spectral data. Most of these compounds exhibited moderate antimicrobial activity. 相似文献