scholarly journals Recognition of Chiral Carboxylates by Synthetic Receptors

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6417
Author(s):  
Patryk Niedbała ◽  
Kajetan Dąbrowa ◽  
Sylwia Wasiłek ◽  
Janusz Jurczak
Keyword(s):  
Chiral Recognition ◽  
Recent Progress ◽  
Spatial Organization ◽  
Anion Recognition ◽  
Synthetic Receptors ◽  
Biologically Relevant ◽  
Environmental Processes ◽  
Anionic Species ◽  
Essential Chemical ◽  
Made In

Recognition of anionic species plays a fundamental role in many essential chemical, biological, and environmental processes. Numerous monographs and review papers on molecular recognition of anions by synthetic receptors reflect the continuing and growing interest in this area of supramolecular chemistry. However, despite the enormous progress made over the last 20 years in the design of these molecules, the design of receptors for chiral anions is much less developed. Chiral recognition is one of the most subtle types of selectivity, and it requires very precise spatial organization of the receptor framework. At the same time, this phenomenon commonly occurs in many processes present in nature, often being their fundamental step. For these reasons, research directed toward understanding the chiral anion recognition phenomenon may lead to the identification of structural patterns that enable increasingly efficient receptor design. In this review, we present the recent progress made in the area of synthetic receptors for biologically relevant chiral carboxylates.

O-AcylTEMPOs, a Modified and Fundamental, but Unexplored Carboxylic Derivative: Recent Progress in Synthetic Applications

2019 ◽  
Vol 23 (19) ◽  
pp. 2102-2121
Author(s):  
Hiroyuki Kawafuchi ◽  
Lijian Ma ◽  
Md Imran Hossain ◽  
Tsutomu Inokuchi
Keyword(s):  
Organic Synthesis ◽  
Recent Progress ◽  
Knoevenagel Condensation ◽  
Acid Synthesis ◽  
Amino Acid Synthesis ◽  
Electrophilic Amination ◽  
Weinreb Amides ◽  
Anionic Species ◽  
Diastereoselective Addition ◽  
Carbonyl Function

O-Acylated 2,2,6,6-tetramethylpiperidine-N-oxyls (abbr. O-AcylTEMPOs) are easily available and stable carboxylic derivatives, but their utility in organic synthesis is unexplored in contrast to analogues, such as the N-methoxy-N-methylamides, known as Weinreb amides. Especially, the O–N unit of the O-acylTEMPOs dictates a fairly electronwithdrawing character for the carbonyl function. This enhances the reactivity and stability of the resulting enolate ions. Accordingly, O-acylTEMPOs allow various transformations and this review encompasses seven topics: (1) Reactivity of O-acylTEMPOs towards nucleophiles and chemoselective transformations, (2) Reactivity of anionic species derived from O-acylTEMPOs, (3) E-Selective Knoevenagel condensation of acetoacetylTEMPOs and synthesis of furans, (4) Electrocyclization of 2,4-dienones derived from acetoacetic derivatives and 2-substituted enals, (5) Diastereoselective addition of amide anion to O-(2-alkenoyl)TEMPOs and β-amino acid synthesis, (6) Thermolysis of O-acylTEMPOs, and (7) Applications for Umpolung reactions using O-benzoylTEMPOs, useful for the electrophilic amination of alkenes and alkynes.

Potential of Nanoparticles in Combating Candida Infections

2019 ◽  
Vol 16 (5) ◽  
pp. 478-491 ◽  
Author(s):  
Faizan Abul Qais ◽  
Mohd Sajjad Ahmad Khan ◽  
Iqbal Ahmad ◽  
Abdullah Safar Althubiani
Keyword(s):  
Targeted Delivery ◽  
Recent Progress ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
Fold Increase ◽  
Antifungal Drugs ◽  
Low Toxicity ◽  
Candida Infections ◽  
Made In

Aims: The aim of this review is to survey the recent progress made in developing the nanoparticles as antifungal agents especially the nano-based formulations being exploited for the management of Candida infections. Discussion: In the last few decades, there has been many-fold increase in fungal infections including candidiasis due to the increased number of immunocompromised patients worldwide. The efficacy of available antifungal drugs is limited due to its associated toxicity and drug resistance in clinical strains. The recent advancements in nanobiotechnology have opened a new hope for the development of novel formulations with enhanced therapeutic efficacy, improved drug delivery and low toxicity. Conclusion: Metal nanoparticles have shown to possess promising in vitro antifungal activities and could be effectively used for enhanced and targeted delivery of conventionally used drugs. The synergistic interaction between nanoparticles and various antifungal agents have also been reported with enhanced antifungal activity.

scholarly journals Principles of Different X-ray Phase-Contrast Imaging: A Review

2021 ◽  
Vol 11 (7) ◽  
pp. 2971
Author(s):  
Siwei Tao ◽  
Congxiao He ◽  
Xiang Hao ◽  
Cuifang Kuang ◽  
Xu Liu
Keyword(s):  
Biological Samples ◽  
Phase Contrast ◽  
Recent Progress ◽  
Phase Contrast Imaging ◽  
Contrast Imaging ◽  
X Ray ◽  
X Ray Imaging ◽  
Internal Structures ◽  
X Ray Absorption ◽  
Made In

Numerous advances have been made in X-ray technology in recent years. X-ray imaging plays an important role in the nondestructive exploration of the internal structures of objects. However, the contrast of X-ray absorption images remains low, especially for materials with low atomic numbers, such as biological samples. X-ray phase-contrast images have an intrinsically higher contrast than absorption images. In this review, the principles, milestones, and recent progress of X-ray phase-contrast imaging methods are demonstrated. In addition, prospective applications are presented.

scholarly journals Bimetallic Ni-Based Catalysts for CO2 Methanation: A Review

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 28
Author(s):  
Anastasios I. Tsiotsias ◽  
Nikolaos D. Charisiou ◽  
Ioannis V. Yentekakis ◽  
Maria A. Goula
Keyword(s):  
Low Temperature ◽  
Noble Metals ◽  
Recent Progress ◽  
Low Cost ◽  
Alloy Formation ◽  
Co2 Methanation ◽  
High Performing ◽  
Mobile Sources ◽  
Low Dispersion ◽  
Made In

CO2 methanation has recently emerged as a process that targets the reduction in anthropogenic CO2 emissions, via the conversion of CO2 captured from point and mobile sources, as well as H2 produced from renewables into CH4. Ni, among the early transition metals, as well as Ru and Rh, among the noble metals, have been known to be among the most active methanation catalysts, with Ni being favoured due to its low cost and high natural abundance. However, insufficient low-temperature activity, low dispersion and reducibility, as well as nanoparticle sintering are some of the main drawbacks when using Ni-based catalysts. Such problems can be partly overcome via the introduction of a second transition metal (e.g., Fe, Co) or a noble metal (e.g., Ru, Rh, Pt, Pd and Re) in Ni-based catalysts. Through Ni-M alloy formation, or the intricate synergy between two adjacent metallic phases, new high-performing and low-cost methanation catalysts can be obtained. This review summarizes and critically discusses recent progress made in the field of bimetallic Ni-M (M = Fe, Co, Cu, Ru, Rh, Pt, Pd, Re)-based catalyst development for the CO2 methanation reaction.

scholarly journals Recent Advances in the Development of Nano-Sculpted Films by Magnetron Sputtering for Energy-Related Applications

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2039 ◽  
Author(s):  
Adriano Panepinto ◽  
Rony Snyders
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Recent Progress ◽  
Dye Sensitized Solar Cells ◽  
Dye Sensitized ◽  
New Generation ◽  
Recent Experimental Work ◽  
Sensitized Solar Cells ◽  
Theoretical Results ◽  
Made In

In this paper, we overview the recent progress we made in the magnetron sputtering-based developments of nano-sculpted thin films intended for energy-related applications such as energy conversion. This paper summarizes our recent experimental work often supported by simulation and theoretical results. Specifically, the development of a new generation of nano-sculpted photo-anodes based on TiO2 for application in dye-sensitized solar cells is discussed.

Ionic liquids as bioactive chemical tools for use in agriculture and the preservation of agricultural products

2018 ◽  
Vol 20 (21) ◽  
pp. 4764-4789 ◽  
Author(s):  
Adrian Zajac ◽  
Rafal Kukawka ◽  
Anna Pawlowska-Zygarowicz ◽  
Olga Stolarska ◽  
Marcin Smiglak
Keyword(s):  
Ionic Liquids ◽  
Recent Progress ◽  
Agricultural Products ◽  
Bioactive Components ◽  
Chemical Tools ◽  
Made In

The review presents the recent progress made in the field of ionic liquids bearing bioactive components, with a particular emphasis on their use as chemical tools in agriculture and the preservation of agricultural products.

scholarly journals Drug Discovery against Acanthamoeba Infections: Present Knowledge and Unmet Needs

Pathogens ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 405 ◽  
Author(s):  
Hany M. Elsheikha ◽  
Ruqaiyyah Siddiqui ◽  
Naveed Ahmed Khan
Keyword(s):  
Recent Progress ◽  
Unmet Needs ◽  
Drug Repurposing ◽  
Present Knowledge ◽  
Current Status ◽  
Therapeutic Landscape ◽  
Pharmacological Targets ◽  
Health Complications ◽  
Interfering Rna ◽  
Made In

Although major strides have been made in developing and testing various anti-acanthamoebic drugs, recurrent infections, inadequate treatment outcomes, health complications, and side effects associated with the use of currently available drugs necessitate the development of more effective and safe therapeutic regimens. For any new anti-acanthamoebic drugs to be more effective, they must have either superior potency and safety or at least comparable potency and an improved safety profile compared to the existing drugs. The development of the so-called ‘next-generation’ anti-acanthamoebic agents to address this challenge is an active area of research. Here, we review the current status of anti-acanthamoebic drugs and discuss recent progress in identifying novel pharmacological targets and new approaches, such as drug repurposing, development of small interfering RNA (siRNA)-based therapies and testing natural products and their derivatives. Some of the discussed approaches have the potential to change the therapeutic landscape of Acanthamoeba infections.

scholarly journals Dihomooxacalix[4]arene-Based Fluorescent Receptors for Anion and Organic Ion Pair Recognition

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4708
Author(s):  
Alexandre S. Miranda ◽  
Paula M. Marcos ◽  
José R. Ascenso ◽  
Mário N. Berberan-Santos ◽  
Rachel Schurhammer ◽  
...  
Keyword(s):  
Chiral Recognition ◽  
Aminobutyric Acid ◽  
Quantum Mechanical ◽  
Anion Receptor ◽  
Binding Properties ◽  
Cone Conformation ◽  
X Ray ◽  
Biologically Relevant ◽  
Alkylammonium Salts ◽  
Fluorescence Titrations

Fluorescent dihomooxacalix[4]arene-based receptors 5a–5c, bearing two naphthyl(thio)ureido groups at the lower rim via a butyl spacer, were synthesised and obtained in the cone conformation in solution. The X-ray crystal structures of 1,3- (5a) and 3,4-dinaphthylurea (5b) derivatives are reported. Their binding properties towards several anions of different geometries were assessed by 1H-NMR, UV-Vis absorption and fluorescence titrations. Structural and energetic insights of the naphthylurea 5a and 5b complexes were also obtained using quantum mechanical calculations. The data showed that all receptors follow the same trend, the association constants increase with the anion basicity, and the strongest complexes were obtained with F−, followed by the oxoanions AcO− and BzO−. Proximal urea 5b is a better anion receptor compared to distal urea 5a, and both are more efficient than thiourea 5c. Compounds 5a and 5b were also investigated as heteroditopic receptors for biologically relevant alkylammonium salts, such as the neurotransmitter γ-aminobutyric acid (GABA·HCl) and the betaine deoxycarnitine·HCl. Chiral recognition towards the guest sec-butylamine·HCl was also tested, and a 5:2 selectivity for (R)-sec-BuNH3+·Cl− towards (P) or (M) enantiomers of the inherently chiral receptor 5a was shown. Based on DFT calculations, the complex [(S)-sec-BuNH3+·Cl−/(M)-5a] was indicated as the more stable.

The Hsp90 molecular chaperone: an open and shut case for treatment

2008 ◽  
Vol 410 (3) ◽  
pp. 439-453 ◽  
Author(s):  
Laurence H. Pearl ◽  
Chrisostomos Prodromou ◽  
Paul Workman
Keyword(s):  
Molecular Chaperone ◽  
Recent Progress ◽  
Morphological Evolution ◽  
Future Research ◽  
Accessory Proteins ◽  
Control Mechanisms ◽  
N Terminus ◽  
Client Proteins ◽  
Atp Binding And Hydrolysis ◽  
Made In

The molecular chaperone Hsp90 (90 kDa heat-shock protein) is a remarkably versatile protein involved in the stress response and in normal homoeostatic control mechanisms. It interacts with ‘client proteins’, including protein kinases, transcription factors and others, and either facilitates their stabilization and activation or directs them for proteasomal degradation. By this means, Hsp90 displays a multifaceted ability to influence signal transduction, chromatin remodelling and epigenetic regulation, development and morphological evolution. Hsp90 operates as a dimer in a conformational cycle driven by ATP binding and hydrolysis at the N-terminus. The cycle is also regulated by a group of co-chaperones and accessory proteins. Here we review the biology of the Hsp90 molecular chaperone, emphasizing recent progress in our understanding of structure–function relationships and the identification of new client proteins. In addition we describe the exciting progress that has been made in the development of Hsp90 inhibitors, which are now showing promise in the clinic for cancer treatment. We also identify the gaps in our current understanding and highlight important topics for future research.

Serum albumin: recent progress in the understanding of its structure and biosynthesis.

1977 ◽  
Vol 23 (1) ◽  
pp. 5-12 ◽  
Author(s):  
T Peters
Keyword(s):  
Serum Albumin ◽  
Recent Progress ◽  
Secreted Proteins ◽  
Long Chain Fatty Acids ◽  
The Past ◽  
Covalent Structure ◽  
Clinical Methodology ◽  
Single Peptide ◽  
Long Chain ◽  
Made In

Abstract Major discoveries have been made in the past few years on the structure and mode of biosynthesis of serum albumin. The complete amino acid sequence of this protein has been determined, and its covalent structure shown to be a single peptide chain grouped into a series of nine disulfide-bonded loops. These loops appear to associate into three similar domains. By study of isolated fragments of the molecule it can be demonstrated that the binding of billirubin and the primary binding of long-chain fatty acids are functions of separate domains. The biosynthesis of albumin has been found to involve a precursor form, termed "proalbumin", in which a basic hexapeptide is attached to the amino end of the chain. Similar precursor forms are now known to have a role in the formation of other secreted proteins, but in the case of albumin the purpose of the additional peptide is not clear. Clinical methodology for albumin assay has advanced but little despite--or perhaps in part because of--the increasing use of automation. Hope for improvement is foreseen in the advent of immunochemical procedures and in a better understanding of the specificity of dye-binding reactions.

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