Micro Scale Procedure for Analysis of Andrographolide in Andrographis paniculata Leaves

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatographic (HPTLC) method has been established for quantitative analysis of andrographolide, the...     

Validated HPTLC Method for Assay of Prednisolone in Tablets and Comparison with Pharmacopeial Methods

JPC – Journal of Planar Chromatography – Modern TLC - A rapid and reliable high-performance thin-layer chromatographic method has been established for analysis of prednisolone in a...     

Bichromatically driven double well: parametric perspective of the strong field control landscape reveals the influence of chaotic states

The aim of this work is to understand the influence of chaotic states in control problems involving strong fields. Towards this end, we numerically construct and study the strong field control landscape of a bichromatically driven double well. A novel measure based on correlating the overlap intensities between Floquet states and an initial phase space coherent state with the parametric motion of the quasienergies is used to construct and interpret the landscape features. "Walls" of no control, which are robust under variations of the relative phase between the fields, are seen on the control landscape and associated with multilevel interactions involving chaotic Floquet states.     

Lie symmetry analysis,optimal system,and generalized group invariant solutions of the (2 + 1)-dimensional Date–Jimbo–Kashiwara–Miwa equation

In this work, Lie group theoretic method is used to carry out the similarity reduction and solitary wave solutions of (2 + 1)-dimensional Date–Jimbo–Kashiwara–Miwa (DJKM) equation. The equation describes the propagation of nonlinear dispersive waves in inhomogeneous media. Under the invariance property of Lie groups, the infinitesimal generators for the governing equation have been obtained. Thereafter, commutator table, adjoint table, invariant functions, and one-dimensional optimal system of subalgebras are derived by using Lie point symmetries. The symmetry reductions and some group invariant solutions of the DJKM equation are obtained based on some subalgebras. The obtained solutions are new and more general than the rest while known results reported in the literature. In order to show the physical affirmation of the results, the obtained solutions are supplemented through numerical simulation. Thus, the solitary wave, doubly soliton, multi soliton, and dark soliton profiles of the solutions are traced to make this research physically meaningful.     

The Double‐Histidine Cu2+‐Binding Motif: A Highly Rigid,Site‐Specific Spin Probe for Electron Spin Resonance Distance Measurements

The development of ESR methods that measure long‐range distance distributions has advanced biophysical research. However, the spin labels commonly employed are highly flexible, which leads to ambiguity in relating ESR measurements to protein‐backbone structure. Herein we present the double‐histidine (dHis) Cu²⁺‐binding motif as a rigid spin probe for double electron–electron resonance (DEER) distance measurements. The spin label is assembled in situ from natural amino acid residues and a metal salt, requires no postexpression synthetic modification, and provides distance distributions that are dramatically narrower than those found with the commonly used protein spin label. Simple molecular modeling based on an X‐ray crystal structure of an unlabeled protein led to a predicted most probable distance within 0.5 Å of the experimental value. Cu²⁺ DEER with the dHis motif shows great promise for the resolution of precise, unambiguous distance constraints that relate directly to protein‐backbone structure and flexibility.     

A Rationally Designed Bimetallic Platinum (II)-Ferrocene Antitumor Agent Induces Non-Apoptotic Cell Death and Exerts in Vivo Efficacy

Despite phenomenal clinical success, the efficacy of platinum anticancer drugs is often compromised due to inherent and acquired drug resistant phenotypes in cancers. To circumvent this issue, we designed two heterobimetallic platinum (II)-ferrocene hybrids that display multi-pronged anticancer action. In cancer cells, our best compound, 2 , platinates DNA, produces reactive oxygen species, and has nucleus, mitochondria, and endoplasmic reticulum as potential targets. The multi-modal mechanism of action of these hybrid agents lead to non-apoptotic cell death induction which enables circumventing apoptosis resistance and significant improvement in platinum cross resistance profile. Finally, in addition to describing detail mechanistic insights, we also assessed its stability in plasma and demonstrate anticancer efficacy in an in vivo A2780 xenograft model. Strikingly, compared to oxaliplatin, our compound displays better tolerability, safety profile and efficacy in vivo.     

Buffer‐Stable Chitosan–Polyglutamic Acid Hybrid Nanoparticles for Biomedical Applications

In spite of their attractive features, widespread biomedical applications of CS nanoparticles are yet to be realized due to their poor stability in physiological conditions, such as in buffer system at pH 7.4. Buffer‐stable chitosan‐based hybrid NPs (HNPs) are reported and characterized. Buffer stability is achieved by introducing polyglutamic acid to chitosan. The effect of PGA to CS molar ratio and crosslinking on HNP integrity, buffer stability, and biodegradability are studied. Preliminary in vitro studies are carried out to evaluate targeted uptake efficiency of folate conjugated HNPs. Successful demonstration of buffer stability and cancer cell targeting by HNPs achieves important milestones for chitosan‐based nanoparticle technology.

     

The Double‐Histidine Cu2+‐Binding Motif: A Highly Rigid,Site‐Specific Spin Probe for Electron Spin Resonance Distance Measurements

The development of ESR methods that measure long‐range distance distributions has advanced biophysical research. However, the spin labels commonly employed are highly flexible, which leads to ambiguity in relating ESR measurements to protein‐backbone structure. Herein we present the double‐histidine (dHis) Cu²⁺‐binding motif as a rigid spin probe for double electron–electron resonance (DEER) distance measurements. The spin label is assembled in situ from natural amino acid residues and a metal salt, requires no postexpression synthetic modification, and provides distance distributions that are dramatically narrower than those found with the commonly used protein spin label. Simple molecular modeling based on an X‐ray crystal structure of an unlabeled protein led to a predicted most probable distance within 0.5 Å of the experimental value. Cu²⁺ DEER with the dHis motif shows great promise for the resolution of precise, unambiguous distance constraints that relate directly to protein‐backbone structure and flexibility.     

Semireduction of alkynoic acids via a transition metal-free α borylation-protodeborylation sequence

A method for the semi-reduction of alkynoic acids through an α-borylation and subsequent protodeborylation mechanism has been developed. The transition metal-free protocol is achieved through the activation of bis(pinacolato)diboron by an in situ generated carboxylate moiety yielding aryl acrylic acids. Our studies demonstrate an unprecedented dual role for the carboxylate anion that involves the activation of the diboron reagent and a directing effect in the α-borylation.     

Detection of equimolar EDTA and DTPA in spiked wastewater effluents

Ethylenediaminetetraacetic acid (EDTA) and diethylenetriamine-pentaacetic acid (DTPA) are water ‘softening’ agents that are present in numerous household and industrial detergents. Since these particular chelating agents are not significantly degraded during conventional wastewater treatment processes, wastewater treatment plant (WTP) effluents can contain up to 19 µM of EDTA and 7 µM of DTPA. Little, however, is known about the release of EDTA and DTPA from WTPs to rivers. To gain insight, we here report on the development of a cost-effective analytical method. This method is based on the chromatography of a humic acid-cadmium (HA-Cd) complex on a size-exclusion chromatography column (SEC, Sephadex G-15) while using WTP effluents from Lethbridge, Banff and Canmore which contained 10 mM Tris-buffer as the mobile phase (pH 8.2). The intact HA-Cd complex is detected by means of a flame atomic absorption spectrometer (FAAS). The addition of equimolar EDTA and DTPA up to 10 µM allowed us to observe a concentration-dependent increase of the retention time of the main Cd-peak. This behaviour was qualitatively comparable between the WTP effluents and was rationalised by the EDTA/DTPA-mediated mobilisation of Cd from the HA-Cd complex. The signal intensity that corresponded to the mobilised Cd was used to establish calibration curves with corresponding correlation coefficients in the range of 0.950–0.978. Therefore, the developed method yields robust results for realistic concentrations of equimolar EDTA/DTPA in real WTP effluents. The developed method can now be applied to analyse real WTP effluent for the presence of chelating agents, whose concentrations may be expressed as being equivalent to a particular equimolar EDTA/DTPA concentration.