Electrooxidation of Chlorpromazine in Aqueous and Micellar Media and Spectroscopic Studies of the Derived Cationic Free Radical and Dication Species

Summary.  The electrochemical behaviour of chlorpromazine has been examined in phosphate buffers in aqueous as well as micellar media at a pyrolytic graphite electrode surface. Two oxidation peaks were obtained in linear sweep voltammetry of chlorpromazine. The first peak corresponds to the formation of the cationic free radical, which on further 1e⁻-oxidation gives a dication. The spectroscopic changes and kinetics of the cationic free radical and dication species generated during electrooxidation of chlorpromazine were investigated in both media. The decay of the dication was studied chronoamperometrically and was found to follow first-order kinetics with a half-life of ∼25 ms. Surfactants affect both E _p and i _p values. The anionic surfactant SDS has been found to catalyze the reaction of the free radical cation and the dication.     

Characterization of dipeptidylcarboxypeptidase of <Emphasis Type="Italic">Leishmania donovani</Emphasis>: a molecular model for structure based design of antileishmanials

Leishmania donovani dipeptidylcarboxypeptidsae (LdDCP), an angiotensin converting enzyme (ACE) related metallopeptidase has been identified and characterized as a putative drug target for antileishmanial chemotherapy. The kinetic parameters for LdDCP with substrate, Hip-His-Leu were determined as, Km, 4 mM and Vmax, 1.173 μmole/ml/min. Inhibition studies revealed that known ACE inhibitors (captopril and bradykinin potentiating peptide; BPP1) were weak inhibitors for LdDCP as compared to human testicular ACE (htACE) with Ki values of 35.8 nM and 3.9 μM, respectively. Three dimensional model of LdDCP was generated based on crystal structure of Escherichia coli DCP (EcDCP) by means of comparative modeling and assessed using PROSAII, PROCHECK and WHATIF. Captopril docking with htACE, LdDCP and EcDCP and analysis of molecular electrostatic potentials (MEP) suggested that the active site domain of three enzymes has several minor but potentially important structural differences. These differences could be exploited for designing selective inhibitor of LdDCP thereby antileishmanial compounds either by denovo drug design or virtual screening of small molecule databases.     

Raman spectral probe on increased local vibrational modes and phonon lifetimes in Ho3+‐doped Bi2O3 micro‐rods

We report the appearance and enhancement in intensity of impurity related local vibrational modes in Bi₂O₃ : Ho micro‐rods along with normal modes. Pure and Ho‐doped Bi₂O₃ micro‐rods were synthesized by conventional co‐precipitation method at 60 °C. The structural and morphological studies were carried out using powder X‐ray diffraction technique and scanning electron microscopy, respectively. Raman spectroscopic studies reveal the existence of local phonon vibrational modes (LVM) due to the incorporation of Ho³⁺. Harmonic approximation method was employed to find the dopant‐related peak in the Raman spectra. Variation in full width at half maximum for LVM with increase in Ho³⁺ was also investigated. This increase in FWHM indicates the decrease in crystallinity of the doped samples. The phonon lifetime calculation carried out for each samples and the decrease in phonon lifetime with doping concentration make this material a potential candidate for optical and electronic applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Steric interference modification of the hammerhead ribozyme

Although the structure of the hammerhead ribozyme is well characterized, many questions remain about its catalytic mechanism. Extensive evidence suggests the necessity of a conformational change en route to the transition state. We report a steric interference modification approach for investigating this change. By placing large 2' modifications at residues insensitive to structurally conservative 2'-deoxy modifications, we hoped to discover structural effects distal to the site of modification. Of twenty residues tested, six were identified where the addition of 2' bulk inhibits cleavage, even though these bulky modifications could be accommodated in the crystal structure without steric clash. It is proposed that these 2'-modifications inhibit cleavage by preventing formation of the alternate, active conformation. Since these 2' effects are present in both domain I and domain II of the hammerhead, the entire catalytic core must undergo conformational changes during catalysis.     

TLC Determination of Strychnine and Brucine of Strychnos nux vomica in Ayurveda and Homeopathy Drugs

Strychnos nux vomica is an important plant source for drugs of ayurvedic and homeopathic system of medicine. In this paper a thin layer chromatographic (TLC) method has been developed for the quantitative estimation of the two major alkaloids strychnine and brucine in the plant fruit and in ayurvedic and homeopathic drugs. Chloroform–ethyl acetate–diethyl amine (0.5:8.5:1) as mobile phase gave clear separation with no interference between the bioactive markers. The R _f values for strychnine and brucine were 0.55 and 0.42. The TLC method was found to be precise, rugged, robust and accurate with recovery of strychnine in the range 93.11–99.82% and brucine 96.95–99.48%. The limit of detection (LOD) and limit of quantification (LOQ) for strychnine were 1.9 and 8.25 ng and for brucine 2.2 and 9.2 ng respectively.     

Nice derivations over principal ideal domains

In this paper we investigate to what extent the results of Z. Wang and D. Daigle on “nice derivations” of the polynomial ring $k[X,Y,Z]$ over a field k of characteristic zero extend to the polynomial ring $R[X,Y,Z]$ over a PID R, containing the field of rational numbers. One of our results shows that the kernel of a nice derivation on $k[X_1,X_2,X_3,X_4]$ of rank at most three is a polynomial ring over k.     

A survey on Zariski cancellation problem

In this survey article we describe known results and open questions on the Zariski cancellation problem, highlighting recent developments on the problem. We also discuss its close relationship with some of the other central problems on polynomial rings.     

Hypervalent Iodine Oxidation of Hydrazones of Some Nitrogen Heterocyclic Ketones and Aldehydes: An Efficient Synthesis of Fused 1,2,3-Triazoloheterocycles

Fused 1,2,3-triazoloheterocycles have been prepared by iodobenzene diacetate mediated oxidation of hydrazones of nitrogen heterocyclic ketones and aldehydes.