A Stability-Indicating LC Method for Assay of Topotecan Hydrochloride

This paper describes the development of a stability-indicating high-performance liquid chromatographic (HPLC) method for quantitative determination of topotecan hydrochloride, a semi-synthetic derivative of camptothecin and anti-tumor drug with topoisomerase I-inhibitory activity. Chromatographic separation was achieved on a C₁₈ column with a mixture of phosphate buffer and acetonitrile as mobile phase. The method was validated for linearity, accuracy, precision, and robustness. Forced degradation studies were performed by treating bulk samples of topotecan hydrochloride with acid (0.5 M hydrochloric acid), base (0.5 M sodium hydroxide), oxidizing agent (10% v/v hydrogen peroxide), heat (60 °C), and UV light (254 nm).     

Growth and XRD analysis of the diluted magnetic semiconductor Zn1‐xNixO

Diluted magnetic semiconductor compound Zn_1‐xNi_x O (x =0.01, 0.02, 0.03, 0.04 and 0.05) was prepared by sol‐gel method and characterized using powder XRD for the distribution of electrons and bonding in the unit cell. The electronic structural studies of this material were carried out by maximum entropy method (MEM) for the quantitative and qualitative measurement on the inclusion and the effect induced on bonding by Ni doping. The spatial arrangement of charge and the bonding behavior of this material were analyzed from 3D, 2D and 1D density distributions. The evidence for the addition of Ni in the host lattice of Zn is realized. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

C2-symmetric recyclable organocatalyst for enantioselective Strecker reaction for the synthesis of α-amino acid and chiral diamine--an intermediate for APN inhibitor

Recyclable chiral amide-based organocatalyst 5 efficiently catalyzed asymmetric Strecker reaction of various aromatic and aliphatic N-benzhydrylimines with ethyl cyanoformate as cyanide source at -10 °C to give a high yield (95%) of α-aminonitriles with excellent chiral induction (ee, up to 99%) with the added advantage of recyclability. Based on experimental observations a probable mechanism was proposed for this reaction. This protocol with catalyst 5 was extended for the synthesis of (R)-phenylalanine and pharmaceutically important drug intermediate (R)-3-phenylpropane-1,2-diamine in high yield with high enantioselectivity.     

Isolation and Characterization of Low Molecular Weight Glycosaminoglycans from Marine Mollusc Amussium pleuronectus (Linne) using Chromatography

The glycosaminoglycan (GAG) heparin is a polyanionic sulfated polysaccharide most recognized for its anticoagulant activity. In the present study, the GAGs were extracted from bivalve mollusc Amussium pleuronectus. The crude GAGs were fractionated by ion-exchange (DEAE-cellulose and Amberlite IRA-900 & 120) chromatography. The recovered active fractions (as determined by metachromatic assay) were confirmed by agarose gel electrophoresis and the active fractions were purified in Sephadex G-100 column. Fractionated and purified GAG molecular weight was determined through gradient polyacrylamide gel electrophoresis. The structural characterization of low molecular weight GAG was analyzed by Fourier transform infrared spectroscopy. The activated partial thromboplastin time of purified GAG is 95 IU/mg and has molecular weight 6,500–7,500 Da. The disaccharide compositional analysis on the GAG sample was sulfated like porcine intestinal mucosal heparan sulfate, and it contains equivalent amount of uronic acid and hexosamine. The results of this study suggest that the GAG from A. pleuronectus could be an alternative source of heparin.     

Preventive Effect of Low Molecular Weight Glycosaminoglycan from <Emphasis Type="Italic">Amussium pleuronectus</Emphasis> (Linne) on Oxidative Injury and Cellular Abnormalities in Isoproterenol-Induced Cardiotoxicity in Wistar Rats

The present work explores suspicious consequence of low molecular weight glycosaminoglycan (LMW-GAG) on oxidative stress and cellular abnormalities in isoproterenol (ISO)-induced myocardial infarction in an experimental model. Group-III male Wistar rats (140 ± 10 g) were administrated by ISO (85 mg ISO/ml subcutaneously (SC) injected at the last two days of a 2–week period). Group-IV rats were treated LMW-GAG plus ISO (300 μg/day per rat SC for 1 week followed by 85 mg/kg ISO on the end last two days of the 2 - weeks). Untreated control (Group-I) and LMW-GAG drug control (Group-II) were also included. Serum and tissue lactate dehydrogenase, aminotransferases, and creatine kinase activities were increased in ISO group, which were normalized by LMW-GAG pretreatment rats. Antioxidant enzymes – superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) activities and non-enzymatic enzyme reduced glutathione (GSH) were decreased in the ISO induced rats, and this was increased by LMW-GAG pretreatment. Increased level of thiobarbituric acid reactive substances (TBARS) in plasma and the heart of ISO treated rats; pre s.c. injected with LMW-GAG to ISO-induced rats decreased the levels of TBARS. Histological examination revealed that the ISO-induced deleterious changes in the heart tissues were offset by LMW-GAG treatment. LMW-GAG affords considerable protection to the tissues challenged by cardiotoxicity, evidenced by its correction and restoration of serum and tissue indices of injury, to normalcy.     

Storage performance of LiFe<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>PO<Subscript>4</Subscript> nanoplates (<Emphasis Type="Italic">x </Emphasis>= 0, 0.5, and 1)

Although LiFePO₄ (LFP) is considered to be a potential cathode material for the lithium-ion batteries, its rate performance is significantly restricted by sluggish kinetics of electrons and lithium ions. Several attempts have been made so far to improve the performance of LiFePO₄ by reducing the grain size, doping with aliovalent atoms, and coating conductive materials such as carbon or RuO₂. We report here synthesis of LFP nanoplates by solvothermal method, tailoring the thickness as well as carbon coverage at surfaces to explore their influence on the storage performance. Due to the fact that Li⁺ ion diffuses along the b-axis, solvothermal method was aimed to control the thickness of nanoplates across the b-axis. We synthesized several nanoplates with various plate thicknesses along b-axis; among those, nanoplates of LFP with ～30-nm-thick b-axis having thin (2–5 nm) and uniform layer of carbon coating exhibits high storage capacity as well as high rate performances. Thus, a favorable morphology for LiFePO₄ has been achieved via solvothermal method for fast insertion/extraction of Li⁺ as compared to spherical nanoparticles of carbon-coated LFP. Galvanostatic cycling shows a capacity of 164?±?5 mAh g^?1 at 0.1 C rate, 100?±?5 mAh g^?1 at 10 C rate, and 46?±?5 mAh g^?1 at 30 C rate, with excellent capacity retention of up to 50 cycles. Further attempts have been made to synthesize LiMnPO₄ (LMP) as well as Li(Fe_1???x Mn _x )PO₄/C (x?=?0.5) nanoplates using solvothermal method. Although LiMnPO₄ does not exhibit high storage behavior comparable with that of LiFePO₄, the mixed systems have shown an impressive storage performance.     

The analysis on the rearrangement of charge density distribution in response to magnetic behavior in Mn doped SnO2 nanoparticles

An investigation on the rearrangement of charge density distribution in response to the magnetic behavior is done on the nanosized Sn_1−xMn_xO₂ systems prepared via sol-gel technique. The samples were analyzed using X-ray diffraction, SEM and VSM measurements. The charge ordering is found as a signature to its magnetic response from the reconstruction of the charge density in the unit cell derived from the MEM/Rietveld analysis of the X-ray structure factors. Quantitative investigation is done by analyzing the 3-dimensional, 2-dimensional and 1-dimensional charge density profiles drawn along the bonding directions. The observed para- to dia-magnetic transition with respect to doping concentration of Mn is explained using defect chemistry and the charge ordering. The MEM/Rietveld analysis is used for the first time to analyse the charge and magnetic ordering in the chosen system.     

<em>Cassia spectabilis </em>(DC) Irwin et Barn: A Promising Traditional Herb in Health Improvement

The genus Cassia, comprising about 600 species widely distributed worldwide is well known for its diverse biological and pharmacological properties. Cassia spectabilis (sin Senna spectabilis) (DC) Irwin et Barn (Fabaceae) is widely grown as an ornamental plant in tropical and subtropical areas. C. spectabilis has been commonly used in traditional medicine for many years. Information in the biomedical literature has indicated the presence of a variety of medicinally-important chemical constituents in C. spectabilis. Pharmacological studies by various groups of investigators have shown that C. spectabilis possesses significant biological activity, such as antibacterial, antibiofilm, antifungal and antioxidant properties. Beside this, toxicity studies of this plant have revealed no toxic effect on mice. In view of the immense medicinal importance of C. spectabilis, this review aimed at compiling all currently available information on C. spectabilis's botany, phytochemistry, pharmacology, and mechanism of actions, toxicology and its ethnomedicinal uses.     

Tailoring the structural and magnetic properties of sol-gel derived Sm-Co nanogranular films

In this study, we investigated the microstructure, phase evolution and magnetic properties of nanogranular films of Sm-Co compounds processed by the sol-gel method. By controlling the compositional ratio of Sm:Co precursor concentration, nanogranular films consisting of three distinct hard magnetic phases namely, Sm₂Co₇, SmCo₅ and Sm₂Co₁₇ with coercivity values of 1.78, 2.94 and 2.12 kOe, respectively, were obtained through this technique.     

Charge transfer in CdTe at 200 and 300 K

Using a perfect single crystal sample of CdTe grown using PVT method, the electronic charge transfer in the II–VI compound semiconductor CdTe at 200 and 300 K has been evaluated using two different approaches: (1) by solving a quadratic equation involving the observed structure factors of h+k+l=4n+2 type reflections; and (2) by a graphical approach in which the observed and calculated atomic form factors are extrapolated to sinθ/λ=0, to determine the transferred charge. Precise X-ray structure factors collected using MoK radiation have been used for the analysis. The results obtained are reasonable and clearly indicate the ionicity by which charge is transferred from Cd to Te in CdTe.