An Integrated LC-ESI-MSn and High Resolution LC-ESI-QTOF Approach for the Identification of Phloroglucinols from Nepalese Hypericum japonicum

Phloroglucinols are characteristic constituents of Hypericum japonicum that are claimed to exert several bioactivities, such as anti-inflammatory, anti-depressant and anti-viral ones. Phloroglucinols are unstable compounds and their synthesis is challenging; thus, isolation from natural sources is still one of the main strategies for obtaining these constituents in purified form. Assessing the presence of phloroglucinols in plant materials can be of interest for compound isolation, and LC-MS approaches afford sensitivity and specificity in this regard. In this work, we combined data from quadrupole-time of flight (QTOF) and ion trap (IT) mass spectrometers in order to assess the presence of the phloroglucinols characteristic of H. japonicum and to elucidate their MS fragmentation pathways. The identified compounds present similar structures bearing the 1,3,5-trihydroxybenzene core with different substitutions, which, in constituents at higher MW, is linked to 3′,3′-dimethyl-6′-oxo-phlorisobutyrophenone by a methylene bridge. Differences in MS² spectra of the considered phloroglucinols are useful for compound identification and differentiation, and to perform dereplication studies. Overall, the proposed approach could be useful for the analysis of phloroglucinols in H. japonicum and other plant species.     

Microwave-assisted rapid and efficient synthesis of chromene-fused pyrrole derivatives through multicomponent reaction and evaluation of antibacterial activity with molecular docking investigation

The current study aimed to identify a new strategy of FeCl₃ catalyzed multicomponent synthesis of substituted 2H-chromene–fused pyrrole derivatives. A series of chromene-based pyrrole prepared by employing an array of 3-nitro-2H-chromenes, aniline, and acetylacetone in toluene under microwave irradiation. Using FeCl₃ as a prompt catalyst and microwave irradiation to synthesize 2H-chromene–fused pyrrole motifs significantly reduces the reaction time and facilitates to high yields (83%-95%). Structure of all synthesized compounds analyzed by spectroscopic analysis. One-pot reaction, short reaction period, and simple experimental procedure are the fascinating properties associated with this protocol. The in vitro antibacterial activity of the entire series was assessed against Staphylococcus aureus and Escherichia coli. Out of all the compounds, 15b and 15h revealed most excellent potency against both the bacterial strains relative to the reference gentamicin. Docking study was employed to determine the possible binding orientation of DNA gyrase with the active sites of chromene-fused pyrrole analog. The docking results show that compounds 15b and 15h have higher binding affinity with energy −8.00 and −8.80 kcal/mol. These results illuminate the mode of binding progression and provide an esteemed pathway for the design and the structural modification of chromene-fused pyrroles as a newly advanced class of antibacterial agent.     

Synthesis and Characterization of Group 12 Metal(I) Complexes Bearing Extremely Bulky Boryl/Silyl Substituted Amide Ligands

Two extremely bulky boryl/silyl-substituted amide ligands, –N{B(DipNCH)₂}(SiR₃) (R = Me ^TBoL, R = Ph ^PhBoL; Dip = 2,6-diisopropylphenyl) were used in the preparation of the group 12 metal halide complexes, ^PhBoLZnBr, {^TBoLCd(μ-I)}₂, ^TBoLHgI, and ^PhBoLHgI. The reduction of these, and two previously reported compounds, ^PhBoLZnBr(THF) and {^PhBoLCd(μ-I)}₂, using a magnesium(I) compound, {(^MesNacnac)Mg}₂ (^MesNacnac = [(MesNCMe)₂CH]^–, Mes = mesityl), were carried out, leading to mixed results. In several cases these reactions led to decomposition, and deposition of the group 12 metal. However, in two instances the homobimetallic metal(I) complexes, ^TBoLM–M^TBoL (M = Zn or Hg), were isolated and crystallographically characterized. The reduction of {^PhBoLCd(μ-I)}₂ afforded the known cadmium(I) complex, ^PhBoLCd–Cd^PhBoL, but also gave a very low yield of the thermally unstable complex, ^PhBoLCd–Mg(THF)(^MesNacnac). The X-ray crystal structure of this compound reveals it to contain the first example of a Cd–Mg bond in a molecular compound.     

$(p,q)$-Analogue of Mittag-Leffler Function with $(p,q)$-Laplace Transform

The aim of this paper is to define $(p, q)$-analogue of Mittag-Leffler Function, by using $(p, q)$-Gamma function. Some transformation formulae are also derived by using the $(p, q)$-derivative. The $(p, q)$-analogue for this function provides elegant generalization of $q$-analogue of Mittag-Leffler function in connection with $q$-calculus. Moreover, the $(p, q)$-Laplace Transform of the Mittag-Leffler function has been obtained. Some special cases have also been discussed.     

Poly(acrylonitrile) ultrafiltration membranes. I. Polymer‐salt‐solvent interactions

Fourier transform infrared spectroscopy was used to study the interactions among LiCl, ZnCl₂, and AlCl₃ with N,N‐dimethylformamide (DMF) and poly(acrylonitrile) (PAN). It was observed that all three salts complex with DMF as well as PAN. The strength of the cation interaction with the >C?O oxygen of DMF was found to be higher than that with the ? CN group of PAN. The >C?O stretching frequency of DMF with ZnCl₂ was red shifted, indicating stronger complex formation compared with other two cations. With the addition of salt, the salt–DMF pseudo solvent was found to become a θ solvent for PAN compared with neat DMF. This change in PAN solvation power was primarily the result of DMF–salt complexation. As a result of the complexation, Mark‐Houwink constant a, was found to reduce from 0.75 (for pure DMF) to ～0.6 for DMF–salt solvents, indicating decreased PAN chain expansion. Comparison of intrinsic viscosity [η] values indicated that addition of salts to PAN–DMF solutions resulted in: (i) decrease in the DMF solvation power, which causes less expanded polymer coils, and (ii) increased interpolymer chain entanglements via salt‐promoted chain association. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2061–2073, 2005     

TLC Supplemented by UV Spectrophotometry Compared with HPLC for Separation and Determination of Some Antidiabetic Drugs in Pharmaceutical Preparations

JPC – Journal of Planar Chromatography – Modern TLC - A simple and sensitive method for separation and quantitative determination of antidiabetic drugs in pharmaceutical preparations...     

Polarization mode dispersion in single mode optical fibers due to core-ellipticity

The variation of polarization mode dispersion (PMD) with V-parameter in single mode optical fibers due to core-ellipticity is studied by performing numerical simulations taking into account both geometrical and thermal-stress-induced birefringences as well as the variation of fiber refractive indices with wavelength. Simple empirical relations are given for calculating the mean PMD for any value of core-ellipticity and V-parameter of a standard single mode fiber. It is observed that the mean PMD saturates for V ? 1.8 leading to very small second order PMD.     

Ligand-Exchange TLC Resolution of Some Racemic β-Adrenergic Blocking Agents

JPC – Journal of Planar Chromatography – Modern TLC -