Nanostructured Lipid Carriers-Hydrogels System for Drug Delivery: Nanohybrid Technology Perspective

Advanced hybrid component development in nanotechnology provides superior functionality in the application of scientific knowledge for the drug delivery industry. The purpose of this paper is to review important nanohybrid perspectives in drug delivery between nanostructured lipid carriers (NLC) and hydrogel systems. The hybrid system may result in the enhancement of each component’s synergistic properties in the mechanical strength of the hydrogel and concomitantly decrease aggregation of the NLC. The significant progress in nanostructured lipid carriers–hydrogels is reviewed here, with an emphasis on their preparation, potential applications, advantages, and underlying issues associated with these exciting materials.     

Synthesis of stannic(IV) complexes: Their structural elucidation in solid and solution state and antimicrobial activity

A series of organotin(IV) thiocarboxylates have been synthesized with the general formula R₂SnL₂ and R₃SnL (R = Ph₂(I), Me₃(II), n‐Bu₃(III), Ph₃(IV), Cy₃(V), Me₂(VI), n‐Bu₂(VII), and L = piperidine‐1‐thiocarboxylic acid) in anhydrous toluene under the reflux conditions. The complexes were characterized by microanalysis, IR, ¹H and ¹³C NMR, mass spectrometry, and XRD. NMR data revealed that thiocarboxylic acid acts as bidentate, and complexes exhibit the four‐coordinated geometry in solution state. In solid state, diorganotin complexes exhibit the hexa‐coordinated geometry whereas the triorganotin(IV) compounds show the five‐coordinated geometry. These complexes were also tested for their antimicrobial activity along with the ligand against different animals, plant pathogens, and Artemia salina. All complexes with few exceptions show high activity as compared to the ligand. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:664–674, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20380     

A UPLC-DAD-Based Bio-Screening Assay for the Evaluation of the Angiotensin Converting Enzyme Inhibitory Potential of Plant Extracts and Compounds: Pyrroquinazoline Alkaloids from Adhatoda vasica as a Case Study

Angiotensin converting enzyme (ACE) plays a crucial role in regulating blood pressure in the human body. Identification of potential ACE inhibitors from medicinal plants supported the idea of repurposing these medicinal plants against hypertension. A method based on ultra-performance liquid chromatography (UPLC) coupled with a diode array detector (DAD) was used for the rapid screening of plant extracts and purified compounds to determine their ACE inhibitory activity. Hippuryl-histidiyl-leucine (HHL) was used as a substrate, which is converted into hippuric acid (HA) by the action of ACE. A calibration curve of the substrate HHL was developed with the linear regression 0.999. The limits of detection and quantification of this method were found to be 0.134 and 0.4061 mM, respectively. Different parameters of ACE inhibitory assay were optimized, including concentration, incubation time and temperature. The ACE inhibition potential of Adhatoda vasica (methanolic-aqueous extract) and its isolated pyrroquinazoline alkaloids, vasicinol (1), vasicine (2) and vasicinone (3) was evaluated. Compounds 1–3 were characterized by various spectroscopic techniques. The IC₅₀ values of vasicinol (1), vasicine (2) and vasicinone (3) were found to be 6.45, 2.60 and 13.49 mM, respectively. Molecular docking studies of compounds 1–3 were also performed. Among these compounds, vasicinol (1) binds as effectively as captopril, a standard drug of ACE inhibition.     

Neuroprotective Potential of Synthetic Mono-Carbonyl Curcumin Analogs Assessed by Molecular Docking Studies

Cognitive decline in dementia is associated with deficiency of the cholinergic system. In this study, five mono-carbonyl curcumin analogs were synthesized, and on the basis of their promising in vitro anticholinesterase activities, they were further investigated for in vivo neuroprotective and memory enhancing effects in scopolamine-induced amnesia using elevated plus maze (EPM) and novel object recognition (NOR) behavioral mice models. The effects of the synthesized compounds on the cholinergic system involvement in the brain hippocampus and their binding mode in the active site of cholinesterases were also determined. Compound h2 (p < 0.001) and h3 (p < 0.001) significantly inhibited the cholinesterases and reversed the effects of scopolamine by significantly reducing TLT (p < 0.001) in EPM, while (p < 0.001) increased the time exploring the novel object. The % discrimination index (DI) was significantly increased (p < 0.001) in the novel object recognition test. The mechanism of cholinesterase inhibition was further validated through molecular docking study using MOE software. The results obtained from the in vitro, in vivo and ex vivo studies showed that the synthesized curcumin analogs exhibited significantly higher memory-enhancing potential, and h3 could be an effective neuroprotective agent. However, more study is suggested to explore its exact mechanism of action.     

Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent-cis-195A and cis-211A

The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis-211A was determined to be 2R, 4aR, 5R, 6S, and 8aS. Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis-211A was the mirror image of that of cis-195A, although both alkaloids were isolated from the same poison frog species, Oophaga (Dendrobates) pumilio, from Panama.     

Cobalt–Carbon Nanoparticles with Silica Support for Uptake of Cationic and Anionic Dyes from Polluted Water

Silica-supported hierarchical graphitic carbon sheltering cobalt nanoparticles Co-HGC@SiO₂ (1) were prepared by pyrolysis at 850 °C of [Co(phen)(H₂O)₄]SO₄·2H₂O complex with silica in the presence of pyrene as a carbon source under nitrogen atmosphere. Nanocomposites (2) and (3) were obtained by acid treatment of (1) with HCl and HF acid, respectively. The nanocomposites showed rough hierarchical carbon microstructures over silica support decorated with irregular cobalt nanospheres and nanorods 50 to 200 nm in diameter. The nanoparticles consist of graphitic shells and cobalt cores. SEM, EDAX and TEM elemental mapping indicate a noticeable loss of cobalt in the case of (2) and loss of cobalt and silica in the case of (3) with an increase in porosity. Nanocomposite (3) showed the highest BET surface area 217.5 m²g⁻¹. Raman spectrum shows defect D-band and graphitic G-band as expected in carbon nanostructures. PXRD reveals the presence of cobalt(0) nanoparticles. XPS indicates the presence of Co(II) oxides and the successful doping of nitrogen in the nanocomposites. Moreover, TEM elemental mapping provides information about the abundance of Si, Co, C, N and S elements in zones. Nanocomposite (1) showed maximum uptake capacity of 192.3 and 224.5 mg/g for crystal violet CV and methyl orange MO dyes, respectively. Nanocomposite (2) showed a capacity of 94.1 and 225.5 mg/g for CV and MO dyes, respectively. Nanocomposite (4) obtained after treatment of (1) with crystal violet proved successful adsorption of CV. Co-HGC (5) prepared without addition of silica has a capacity for CV equal to 192 mg/g, while it is 769.2 mg/g with MO. Electrostatics and π–π interactions of graphite and cobalt species in the nanocomposites with aromatic rings of cationic and anionic dyes are responsible for the adsorption. Yan et al. was the best model to describe column kinetics. The thomas column adsorption model showed that the maximum uptake capacity of (1) was 44.42 mg/g for CV and 32.62 mg/g for MO. for a column packed with 0.5 gm of (1) and dye concentration of 100 mg/L at a flow rate of 1 mL/min. The column was recycled three times with no noticeable clogging or degradation of nanocomposites. Thus, Co-HGC@SiO₂ adsorbents can be used efficiently to treat water contaminated with cationic and anionic dyes.     

Substrate induced generation of transient self-assembled catalytic systems

Living matter is sustained under non-equilibrium conditions via continuous expense of energy which is coordinated by complex organized events. Spatiotemporal control over exquisite functions arises from chemical complexity under non-equilibrium conditions. For instance, extant biology often uses substrate binding events to access temporally stable protein conformations which show acceleration of catalytic rates to subsequently degrade the substrate. Furthermore, thermodynamically activated but kinetically stable esters (GTP) induce the change of conformation of cytoskeleton proteins (microtubules) which leads to rapid polymerization and triggers an augmentation of catalytic rates to subsequently degrade the ester. Importantly, high-energy assemblies composed of non-activated building blocks (GDP-tubulin) are accessed utilizing the energy dissipated from the catalytic conversion of GTP to GDP from the assembled state. Notably, some experimental studies with simple self-assembled systems have elegantly mimicked the phenomena of substrate induced transient generation of catalytic conformations. Through this review, we endeavour to highlight those select studies which have used simple building blocks to demonstrate substrate induced self-assemblies that subsequently show rate acceleration to convert the substrate into waste. The concept of substrate induced self-assembly of building blocks and rate acceleration from the assembled state has the potential to play a predominant role in the preparation of non-equilibrium systems. The design strategies covered in this review can inspire the possibilities of accessing high energy self-assembled structures that are seen in living systems.

This review highlights the studies which show substrate induced generation of transient catalytic moieties. Examples have been discussed with keeping an eye on the design strategies for development of non-equilibrium high energy assemblies as seen in Nature.     

应用于量子含时波包方法的高精度透明边界条件

本文提出了一种适用于量子含时波包方法的透明边界条件. 该量子含时波包方法结合分离变量表象方法使用的时候,本质上是具有谱收敛性质的. 相对于以往的复数吸收势,该透明边界条件的突出优点是其对于波函数的能谱分布并不敏感. 采用具有共振态的一维势垒散射模型,本文对该方法的特点做了阐述.     

5-Endo-dig cyclizations in organic syntheses

Molecular Diversity - The favorability of ring closure reactions as per Baldwin rules has gained immense importance recently. This is evident from the current literature such as research articles,...