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Mone M.K.,Drug Discovery Facility | Mone M.K.,Jawaharlal Nehru University | Chandrasekhar K.B.,Jawaharlal Nehru University
Journal of Pharmaceutical and Biomedical Analysis | Year: 2010

Pentoxifylline was subjected to various stress conditions and degradation profile was studied with conventional LCMS. Interestingly, under oxidative stress conditions the drug substance underwent distinct transformation to give rise to a single major degradation product. The structure of this product was elucidated using 1D, 2D NMR spectroscopy, high resolution mass spectrometry (Q-TOF LC/MS) and found to be a novel gem-dihydroperoxide, namely 1-(5,5-Bis-hydroperoxy-hexyl)-3,7-dimethyl-3,7-dihydro-purine-2,6-dione. An efficient stability indicating liquid chromatographic separation method was developed for pentoxifylline and its three degradation products (including two from base hydrolysis) using 1.8 μm, C18 reverse phase column and UHPLC. Baseline separation was achieved with a run time of 4. min. The analytical assay method was validated with respect to system suitability, specificity, linearity, range, precision, accuracy and robustness. © 2010 Elsevier B.V. Source


Mone M.K.,Drug Discovery Facility | Mone M.K.,Jawaharlal Nehru University | Chandrasekhar K.B.,Jawaharlal Nehru University
Journal of Pharmaceutical and Biomedical Analysis | Year: 2011

Chiral separation method development was carried out for eslicarbazepine acetate and its (R)-enantiomer on diverse chiral stationary phases. Better chiral selectivity was observed on cellulose tris-(3,5-dichlorophenylcarbamate) immobilized column (Chiralpak IC-3). Under polar organic mode (POM), with 100% acetonitrile as mobile phase and 0.5. ml/min flow, a resolution close to three was achieved. With normal phase (NP) mobile phase consisting dichloromethane:ethanol (90:10, v/v) and 1.0. ml/min flow, a resolution close to six was achieved. Detection was done by UV at 220 and 240. nm respectively. Both the methods were found to be robust and were validated with respect to robustness, precision, linearity, limit of detection, limit of quantification and accuracy. The proposed methods are suitable for the accurate estimation of (R)-enantiomer in bulk drug samples up to 0.1% when a 1. mg/ml analyte test solution is chromatographed. © 2010 Elsevier B.V. Source


Mone M.K.,Drug Discovery Facility | Mone M.K.,Jawaharlal Nehru University | Chandrasekhar K.B.,Jawaharlal Nehru University
Chromatographia | Year: 2011

Increased throughput in medicinal chemistry has substantially increased the production of new chiral chemical entities with diverse structural features, requiring fast chiral screening strategies. In an effort to explore screening methods we have developed and evaluated gradients in polar organic and normal phase modes on three popular chiral stationary phases using a sample set of 19 racemic compounds. When compared, gradients performed on par with the isocratic methods besides proving to be advantageous in terms of speed of analysis and elution capacity. MS detection was successfully applied to the analysis of a pooled sample consisting 19 compounds to speed-up the screening process. © Springer-Verlag 2011. Source


Bhosale S.,Drug Discovery Facility | Vyavahare V.P.,Drug Discovery Facility | Prasad U.V.,Andhra University | Palle V.P.,Drug Discovery Facility | Bhuniya D.,Drug Discovery Facility
Tetrahedron Letters | Year: 2011

A highly efficient and stereo-controlled synthetic strategy has been developed to access syn-diarylheptanoids, for example, 2, 3, 4, and 5b starting from d-glucose as a chiral pool. The 3-(R), 5-(S)-syn-diol stereochemistry present in these heptanoids was obtained after conserving C2 and C4 stereochemistry of d-glucose during the course of synthetic transformation. The key features of this synthetic strategy include: (i) conversion of d-glucose to a known chiral template 6 armored with the required 1,3-syn-diol stereochemistry as well as two terminal aldehyde functionalities for building up customized 'diaryl wings'; (ii) conversion of 6 to 7 via an initial Wittig olefination at the C5-aldehyde; (iii) use of the hemiacetal 7 as a common intermediate to obtain the individual heptanoids via a second Wittig reaction at its anomeric center using appropriately chosen ylides. © 2011 Elsevier Ltd. All rights reserved. Source


Bhosale S.,Drug Discovery Facility | Sonune D.P.,Drug Discovery Facility | Prasad U.V.,Andhra University | Bhuniya D.,Drug Discovery Facility
Tetrahedron Letters | Year: 2012

Magtrieve™ (CrO 2) mediated reactions with benzaldoxime (1a) and its deuterium congener (d-1a) led to the observation of inverse deuterium kinetic isotope effect (i-DKIE) for the substrate's oxidation (Eq. 1a) as well as deoximation (Eq. 2a) process. Disappearance of the starting material 1a and formation of the products - 1,3-dipolar cycloaddition product (4a) as well as benzaldehyde (3a) - followed a typical 1st-order kinetics. The observed k D/k H values, in the range of 2-4, suggest for a strong secondary isotope effect which was further evidenced by the fact that d-labeling was retained in 3a. Therefore, the observed i-SDKIE supports our original hypothesis that aldoxime (with sp 2-C) interacts with CrO 2 in a rate determining step to form a tetrahedral (now with sp 3-C) structure, possibly like 6, which may act as a common intermediate for both the pathways. © 2012 Elsevier Ltd. All rights reserved. Source

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