Organomediated Enantioselective 18F Fluorination for PET Applications

The first organomediated asymmetric ¹⁸F fluorination has been accomplished using a chiral imidazolidinone and [¹⁸F]N‐fluorobenzenesulfonimide. The method provides access to enantioenriched ¹⁸F‐labeled α‐fluoroaldehydes (>90 % ee), which are versatile chiral ¹⁸F synthons for the synthesis of radiotracers. The utility of this process is demonstrated with the synthesis of the PET (positron emission tomography) tracer (2S,4S)‐4‐[¹⁸F]fluoroglutamic acid.     

Gas-sensing properties of Fe2−xTixO3+γ (x = 0–1.4)

As part of a systematic study of mechanisms of response of semiconducting oxides as trace gas sensors, we have explored the behaviour of iron–titanium oxide solid solutions Fe_2−xTi_xO₃ (x = 0.1–1.4). The materials were single-phase for x = 0.1 with increasing proportions of a pseudobrookite second phase at higher degree of substitution. Unmodified, pure iron oxide does not show sensitivity to CO. A significant signal was developed for x = 0.1, that then diminished with increasing x and was lost for x = 1.4. Three effects have been deduced important for the gas response: significant surface segregation of Ti at low Ti content; grain growth inhibition and agglomeration into more massive, non-porous lumps as Ti content increased; and the appearance of a band-gap state associated with Fe(II) at higher Ti content. The effects of microstructure change have been analyzed by fitting the data to a simple 2-resistor model of gas-insensitive ‘grains’ in series with gas-sensitive ‘grain boundaries’. A Mars–van Krevelen type model for the response is presented, based on reactions at surface-segregated defect clusters, to develop and remove electrically-active surface trap states.     

Selective Reduction in 2′-Hydroxychalcones

The selective reduction of double bond in 2′-hydroxy-chalcones with sodium dithionite under phase transfer catalysed conditions is described.     

QbD‐oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid–liquid extraction and chromatographic separation

The present studies describe the systematic quality by design (QbD)‐oriented development and validation of a simple, rapid, sensitive and cost‐effective reversed‐phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C₁₈ column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box–Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid–liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd.     

Proton magnetic resonance spectroscopy and biochemical investigation of type 2 diabetes mellitus in Asian Indians: observation of high muscle lipids and C-reactive protein levels

We report the determination of intramyocellular lipids (IMCLs) of the soleus muscle of patients with type 2 diabetes mellitus (T2DM) using proton magnetic resonance spectroscopy. In addition, the various anthropometric and biochemical profiles of these patients were determined, including estimation of C-reactive protein (CRP), an inflammatory marker of coronary heart disease, and insulin resistance [Homeostasis Model Assessment (HOMA-IR)]. The estimated CRP level and the IMCL content in these patients were correlated with body mass index, percentage of body fat, other measures of abdominal obesity, serum lipoproteins, fasting and post-oral glucose load serum insulin levels and other surrogate markers of insulin resistance. The IMCL content (P=.04), CRP (P=.008) and insulin resistance (P=.0007) were significantly higher in T2DM patients compared to healthy controls. However, IMCL content did not correlate with values of fasting insulin, HOMA-IR or CRP in either group. These findings have strong implications of increased cardiovascular risk in Asian Indians with T2DM. The absence of relationship between CRP and IMCL needs to be explored further in a study using a large sample size.     

Solid-state graphene-based supercapacitor with high-density energy storage using ionic liquid gel electrolyte: electrochemical properties and performance in storing solar electricity

Journal of Solid State Electrochemistry - The electrochemical properties and high-density energy storage performance of graphene nano-platelet-based solid-state electrical double-layer...     

Development and Validation of Highly Sensitive LC–ESI-MS/MS Method for Bortezomib and Its Applications for Plasma Levels and Drug Content of Branded and Generic Formulations in India

In the present study, a highly sensitive and reproducible bio-analytical method was developed using LC–ESI-MS/MS to assess the lower plasma levels of bortezomib in multiple myeloma patients. The gradient elution was optimized using reverse-phase C18 column with mobile phases consisting of water and acetonitrile in 0.1% formic acid. Multiple reaction monitoring mode was used for quantification using precursor-to-product ion transition for bortezomib and sulfadiamethoxine was used as internal standard. This method was validated with a linearity range of 0.195–25 ng mL^?1. Intra-day and inter-day accuracy was 99.17–101.89% and 95.01–102.92% with precision of?<?9.87% and?<?8.77%, respectively. Bortezomib was stable in plasma samples stored at ? 80 °C for up to 10 months. The lower limit of quantification was found to be 0.195 ng mL^?1. This method was also found to be capable of quantifying bortezomib trough levels (ranging 0.19–0.7 ng mL^?1) in plasma of multiple myeloma patients post-cycle 1–6. Bortezomib content in the commonly prescribed generic formulations was also studied. The concentration in all formulations was within the 90–110% of the innovator, as prescribed by the USFDA, ruling out their role blood level variation. The study supports the use of this method for trough level estimation and therapeutic drug monitoring of bortezomib in multiple myeloma patients.