Assessment of Reproducibility of Laser Electrospray Mass Spectrometry using Electrospray Deposition of Analyte

A nonresonant, femtosecond (fs) laser is employed to desorb samples of Victoria blue deposited on stainless steel or indium tin oxide (ITO) slides using either electrospray deposition (ESD) or dried droplet deposition. The use of ESD resulted in uniform films of Victoria blue whereas the dried droplet method resulted in the formation of a ring pattern of the dye. Laser electrospray mass spectrometry (LEMS) measurements of the ESD-prepared films on either substrate were similar and revealed lower average relative standard deviations for measurements within-film (20.9%) and between-films (8.7%) in comparison to dried droplet (75.5% and 40.2%, respectively). The mass spectral response for ESD samples on both substrates was linear (R²?>?0.99), enabling quantitative measurements over the selected range of 7.0?×?10^?11 to 2.8?×?10^?9 mol, as opposed to the dried droplet samples where quantitation was not possible (R²?=?0.56). The limit of detection was measured to be 210 fmol.

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Synthesis of threo- and erythro-configured trihydroxy open chain lipophilic ketones as possible anti-mycobacterial agents

A series of threo- and erythro-configured open-chain trihydroxy ketones was synthesized starting from l- and d-ascorbic acid respectively as the starting material, through the use of Grignard reactions for the requisite CC bond formations. The lipophilic ketones were screened against Mycobacteriumtuberculosis for anti-proliferative activity. The lipophilic ketones with tetradecyl alkyl side chains were found to be moderately active against cell proliferation.     

Clionasterol Glucoside and Acylated Clionasterol Glucosides from Oplismenus burmannii

A new clionasterol glucoside, clionasterol‐[(1'→3α)‐O‐β‐D]‐glucopyranoside ( 1 ), a new acylated clionasterol glucoside, clionasterol‐[6'‐O‐acyl‐(1'→3β)‐O‐b‐D]‐glucopyranoside ( 2 ) and clionasterol ( 3 ) were isolated from the aerial parts of Oplismenus burmannii. The nature and length of fatty acid acyl chains in 2 was identified by alkaline methanolysis of compound 2 . The aglycone fraction on GC‐MS analysis showed three peaks in GC at t_R 49.86 (82.1%), 51.13 (13.3%) and 56.53 (4.6%) min, which were characterized as arachidic acid methyl ester ( a ) oleic acid methyl ester ( b ) and 12‐methyltetradecanoic acid methyl ester ( c ) respectively. Thus 2 was characterized as a mixture of three new compounds, clionasterol‐[6'‐O‐eicosanoyl‐(1'→3β)‐O‐β‐D]‐glucopyranoside ( 2a ), clionasterol‐[6'‐O‐(8Z)‐octa‐deca‐9‐enoyl‐(1'→3β)‐O‐β‐D]‐glucopyranoside ( 2b ) and clionasterol‐[6'‐O‐(12‐methyltetradecanoyl)‐(1'→3β)‐O‐β‐D]‐glucopyranoside ( 2c ).     

Alkyl radical cyclization to vinylogous carbonates for the stereoselective synthesis of unsymmetrical dioxa-cage compounds: effect of conformation on the rate of cyclization versus reduction

An efficient strategy for the stereoselective construction of unsymmetrical dioxa-cage compounds containing ether linkages employing a 6-exo-trig alkyl radical cyclization to vinylogous carbonates is developed. The radical precursors are prepared from the diols obtained from the Diels-Alder adducts via iodoetherification followed by addition of the alcohol to the ethyl propiolate. The geometrical constrains play important role in deciding the outcome of the reaction as cyclization versus simple reduction. Formation of the mono-oxa-cage compounds via a 5-exo-trig intramolecular alkyl radical cyclization to olefin is also described. The dioxa-cages could also be assembled employing a tandem oxymercuration reduction-radical cyclization to vinylogous carbonates protocol with equal efficiency and with reduced number of steps.     

Solute�CSolvent Interactions in Aqueous Glycylglycine�CCuCl2 Solutions: Acoustical and Molecular Dynamics Perspective

Acoustical and molecular dynamics studies were carried out to understand the various interactions present in glycylglycine?CCuCl₂ aqueous solutions. Amongst these interactions, hydrogen bonding and solute?Csolvent interactions have been highlighted in this study. The radial distribution function (RDF) was used to investigate solution structure and hydration parameters. Binding of Cu²⁺ with various polar peptide atoms reveals the nature and degree of binding. The formation of complex clusters between glycylglycine and water molecules increases the relaxation time. The first hydration shell considerably influences the structure of the second shell, facilitating the formation of an ordered hydrogen bonded network. Both experimental and theoretical results have proved to be efficient in analyzing the behavior of molecules and to give a clear idea on molecular interactions in solutions.     

Syntheses, transfection efficacy and cell toxicity properties of novel cholesterol-based gemini lipids having hydroxyethyl head group

We have synthesized five new cholesterol based gemini cationic lipids possessing hydroxyethyl (-CH(2)CH(2)OH) function on each head group, which differ in the length of the polymethylene spacer chain. These gemini lipids are important for gene delivery processes as they possess pre-optimized molecular features, e.g., cholesterol backbone, ether linkage and a variable spacer chain between both the headgroups of the gemini lipids. Cationic liposomes were prepared from each of these lipids individually and as a mixture of individual cationic gemini lipid and 1,2-dioleoyl phosphatidylethanolamine (DOPE). Each gemini lipid based formulation induced better transfection activity than that of their monomeric counterpart. One such gemini lipid with a -(CH(2))(12)- spacer, HG-12, showed dramatic increase in the mean fluorescence intensity due to the expression of green-fluorescence protein (GFP) in the presence of 10% FBS compared to the conditions where there was no serum. Other gemini lipids retained their gene transfection efficiency without any marked decrease in the presence of serum. The only exception was seen with the gemini with a -(CH(2))(3)- spacer, HG-3, which on gene transfection in the presence of 10% FBS lost ~70% of its transfection efficiency. Overall the gemini lipid with a -(CH(2))(5)- spacer, HG-5, showed the highest transfection activity at N/P (lipid/DNA) ratio of 0.5 and lipid : DOPE molar ratio of 2. Upon comparison of the relevant parameters, e.g., %-transfected cells, the amount of DNA transfected to each cell and %-cell viability all together against Lipofectamine 2000, one of the best commercial transfecting agents, the optimized lipid formulation based on DOPE/HG-5 was found to be comparable. In terms of its ability to induce gene-transfer in the presence of serum and shelf-life DOPE/HG-5 liposome was found to be superior to its commercial counterpart. Confocal imaging analysis confirmed that in the presence of 10% serum using a Lipid : DOPE of 1 : 4 and N/P charge ratio of 0.75 with 1.2 μg DNA per well, HG-5 is better than Lipofectamine 2000.     

Stereoselective synthesis of C-substituted morpholine derivatives using reductive etherification reaction: total synthesis of chelonin C

A general strategy is developed for the stereoselective synthesis of C-substituted morpholine derivatives using intramolecular reductive etherification reaction. The method is extended to the first stereoselective total synthesis of (±)-chelonin C.     

Domino Wittig Diels-Alder reaction: an expeditious entry into the AB ring system of furanosesquiterpenes

A domino Wittig Diels-Alder reaction has been employed in delineating a short and flexible synthetic stratagem for ready access to the AB ring system and the tricyclic framework of furanosesquiterpenes, such as the bioactive natural products, furodysin and furodysinin.     

Kinetics and mechanism of the ruthenium(III)-catalysed oxidation of aminoalcohols by cerium(IV) in a sulphuric acid medium

Summary The kinetics of the ruthenium(III)-catalysed oxidation of primary (viz. 2-aminoethanol and 3-aminopropanol) secondary (diethanolamine) and tertiary aminoalcohols (triethanolamine) by cerium(IV) in a sulphuric acid medium have been studied spectrophotometrically. The reactions exhibit a zero-order rate-dependence with respect to the oxidant and first-order rate-dependence with respect to each of the substrate and catalyst. First order dependence of rate in sulphuric acid is found for primary aminoalcohols. A suitable mechanism, consistent with the observed kinetic data, is proposed.     

Lorentz violation in high-energy ions

The theoretical interest in small Lorentz violations has motivated experiments that investigate it by measuring deviations in the time dilation predicted by special relativity (SR) using high-energy ions. The main contribution of this article is to show that including the Doppler effect in the emission (which is of the same order as the time dilation effect) in the analysis leads to differences between experimental and theoretical predictions that indicate potential Lorentz violation.