A novel tryptamine-appended rhodamine-based chemosensor for selective detection of Hg2+ present in aqueous medium and its biological applications

A novel rhodamine–tryptamine conjugate–based fluorescent and chromogenic chemosensor (RTS) for detection of Hg²⁺ present in water was reported. After gradual addition of Hg²⁺ in aqueous methanol solution of RTS, a strong orange fluorescence and deep-pink coloration were observed. The probe showed high selectivity towards Hg²⁺ compared to other competitive metal ions. The 1:1 binding stoichiometry between RTS and Hg²⁺ was established by Job’s plot analysis and mass spectroscopy. Initial studies showed that the synthesized probe RTS possessed fair non-toxicity and effectively passed through cell walls of model cell systems, viz., human neuroblastoma (SHSY5Y) cells and cervical cells (HeLa) to detect intercellular Hg²⁺ ions, signifying its utility in biological system. The limit of detection (LOD) was found to be 2.1 nM or 0.42 ppb by fluorescence titration. Additionally, the potential relevance of synthesized chemosensor for detecting Hg²⁺ ions in environmental water samples has been demonstrated.

ᅟ

     

Higher isoprenoids—VII: A new approach to the degradation of cyclolaudenol side-chain

An efficient new procedure for the degradation of cyclolaudenyl acetate to 3β - acetoxy - 4,4,14α -trimethyl - 9, 19 - cyclo - 5α - pregnan - 20 - one and/or 3β - acetoxy - 4,4,14α - trimethyl - 9,19 - cyclo - 5α -androstan - 17 - one is described. The key-step is simultaneous base-catalysed dehydrohalogenation and isomerisation of the resulting olefin, of a suitably derived halide.     

Virtual Screening for Potential Phytobioactives as Therapeutic Leads to Inhibit NQO1 for Selective Anticancer Therapy

NAD(P)H:quinone acceptor oxidoreductase-1 (NQO1) is a ubiquitous flavin adenine dinucleotide-dependent flavoprotein that promotes obligatory two-electron reductions of quinones, quinonimines, nitroaromatics, and azo dyes. NQO1 is a multifunctional antioxidant enzyme whose expression and deletion are linked to reduced and increased oxidative stress susceptibilities. NQO1 acts as both a tumor suppressor and tumor promoter; thus, the inhibition of NQO1 results in less tumor burden. In addition, the high expression of NQO1 is associated with a shorter survival time of cancer patients. Inhibiting NQO1 also enables certain anticancer agents to evade the detoxification process. In this study, a series of phytobioactives were screened based on their chemical classes such as coumarins, flavonoids, and triterpenoids for their action on NQO1. The in silico evaluations were conducted using PyRx virtual screening tools, where the flavone compound, Orientin showed a better binding affinity score of −8.18 when compared with standard inhibitor Dicumarol with favorable ADME properties. An MD simulation study found that the Orientin binding to NQO1 away from the substrate-binding site induces a potential conformational change in the substrate-binding site, thereby inhibiting substrate accessibility towards the FAD-binding domain. Furthermore, with this computational approach we are offering a scope for validation of the new therapeutic components for their in vitro and in vivo efficacy against NQO1.     

Diffusion Kinetics of Vitamin B12 from Alginate and Poly(vinyl acetate) Based Gel Scaffolds for Targeted Drug Delivery

Abstract

The research described here probed the thermodynamics and kinetics of Vitamin B₁₂ release from two types of polymeric gel scaffolds for targeted drug delivery applications. The polymeric gel scaffolds were successfully prepared from sodium alginate and polyvinyl acetate (PVA) using crosslinking and casting mechanisms, respectively. Vitamin B₁₂ was effectively blended into the polymeric gel scaffolds during their synthesis processes. The release of Vitamin B₁₂ from the polymeric gel scaffolds was characterized by immersing the scaffolds in a brine solution at various temperatures (25?°C, 32?°C and 37?°C) and, simultaneously, the transient concentrations were measured using a UV visible spectrophotometer. The sodium alginate gel scaffolds exhibited a more rapid release of Vitamin B₁₂ as compared to the PVA gel scaffolds. The Vitamin B₁₂ release kinetics from the alginate and PVA scaffolds were characterized by fitting the experimental data with various diffusion kinetic models. The Vitamin B₁₂ release from the alginate gel scaffolds followed the Peppas-Sahlin model, whereas releases from the PVA gel scaffolds were fitted to the Hopfenberg model. The diffusion coefficients for the alginate scaffolds with respect to the three temperatures were found to be 15.72?m²/s, 17.17?m²/s and 18.58?m²/s respectively whereas the diffusion coefficients for the PVA scaffolds with respect to the three temperatures were found to be 0.23?m²/s, 0.29?m²/s and 0.32?m²/s respectively. The activation energies (E_a) for the two types of polymeric scaffolds were calculated using the Stannett equation and found to be 10.38?kJ.mol^?1 and 20.47?kJ.mol^?1 for the alginate and PVA scaffolds, respectively, for all three temperatures.     

Concise syntheses of (+)- and (−)-methylenolactocins and phaseolinic acids

(+)- and (−)-Methylenolactocins and phaseolinic acids are synthesized in four steps via asymmetric syn- and anti-aldol reactions of chiral N-succinyl-2-oxazolidinones using the same set of reagents.     

Spatiotemporal rheochaos in nematic hydrodynamics

Motivated by recent observations of rheochaos in sheared wormlike micelles, we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order-parameter fields in a sheared nematogenic fluid. In a suitable parameter range, we find irregular, dynamic shear banding and establish by decisive numerical tests that the chaos we observe in the model is spatiotemporal in nature.     

Two-step melting of the vortex solid in layered superconductors with random columnar pins

We consider the melting of the vortex solid in highly anisotropic layered superconductors with a small concentration of random columnar pinning centers. Using large-scale numerical minimization of a free-energy functional, we find that melting of the low-temperature, nearly crystalline vortex solid (Bragg glass) into a vortex liquid occurs in two steps as the temperature increases: the Bragg glass and liquid phases are separated by an intermediate Bose glass phase. A suitably defined local melting temperature exhibits spatial variation similar to that observed in experiments.