Chemoenzymatic Synthesis of 2-Arachidonoylglycerol, An Endogenous Ligand for Cannabinoid Receptors

A simple and efficient synthesis of 2-arachidonoyl glycerol, an endogenous agonist for cannabinoid receptors was achieved using Novozym 435, immobilized lipase from Candida antarctica.     

Development and validation of a HPLC method for quantification of rivastigmine in rat urine and identification of a novel metabolite in urine by LC‐MS/MS

A sensitive, specific and accurate HPLC method for the quantification of rivastigmine (RSM) in rat urine was developed and validated. The method involves the simple liquid–liquid extraction of RSM and pyridostigmine as an internal standard (IS) from rat urine with tertiary methyl butyl ether. The chromatographic separation of RSM and IS was achieved with 20 mm ammonium acetate buffer (pH 6.5) and acetonitrile (65:35, v/v) delivered at flow‐rate of 1 mL/min on a Kromasil KR‐100. The method was in linear range from 50 to 5000 ng/mL. The validation was done as per FDA guidelines and the results met the acceptance criteria. The method was successfully applied for the quantification of RSM in rat urine. Besides method validation, we have identified two metabolites of RSM in urine. Both the metabolites were characterized by HPLC‐PDA and LC‐MS/MS and it was found that one metabolite is novel. Copyright © 2010 John Wiley & Sons, Ltd.     

Cyclic voltammetric measurements of growth of Aspergillus terreus.

A detailed study using the cyclic voltammogram was done on the live cells of Aspergillus terreus. The peak current values were obtained for different days of growth and plotted against time. The response of cyclic voltammogram showed the phases of the growth of the fungus. The growth curve obtained matched well with the conventional methodology, which assesses the increase of dry weight of the organisms against time. The electrochemical method is more advantageous because it is easy to assess and consumes less time. Further the electrochemical method clearly shows the decline phase which is generally not very defined in the conventional method of assessment of the growth curve. It was confirmed by further experiments that the metabolites were responsible for the anodic peak and not the biomass. Further work is in progress in order to analyze the metabolite(s) that is/are responsible for the anodic peak.     

High-Performance Thin-Layer Chromatographic Analysis of Bicalutamide in Bulk Drug and Liposomes

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, accurate, precise, and specific high-performance thinlayer chromatographic (HPTLC) method for analysis of bicalutamide...     

Evaluation of the potential of nonlinear gradients for separating a ternary mixture

The potential of applying nonlinear gradients in preparative chromatography is evaluated theoretically and experimentally. The second eluting component of a ternary model mixture is considered as the target component. Systematic gradient resolution experiments were conducted for this mixture using reversed phase chromatography. In preliminary experimental investigations the effect of the mobile phase composition on the specific distribution equilibria was quantified. Concave and convex solvent strength gradients were analysed and compared with conventional linear gradients. Main result of the study is the fact that significant improvement in productivity can be achieved if the gradient shapes are designed carefully.     

Kinetics of isotopic exchange between chloramine-B and radioactive chloride

The kinetics of chlorine isotope exchange between chloramine-B /CAB/ and chloride has been studied using ion-exchange separation and tracer technique. McKay's plot are linear. The exchange reaction is fast in acidic medium, very slow in neutral medium and does not take place in alkaline medium. In the acidic range the exchange is maximum at pH 3.3. The rate of exchange decreases at pH >3.3 and <3.3. The order with respect to CAB and chloride is unity. The order with respect to [H⁺] is unity at pH>5. Addition of neutral salt or parent compound has no effect on the rate of exchange. Activation energy and activation entropy for this exchange reaction have been calculated.