Indolino-oxazolidine derivatives are a new and pretty confidential family of multimodal molecular switch. Indeed, acid, electrochemical potential, and UV light irradiation can be used to convert these compounds form their colorless closed form to a colorful open form. In this publication, we have investigated the influence of the extension of the p-conjugated system beared by the indolino moiety on their halo-, electro- and photochromic properties. In this context, we have demonstrated that only their photochemical properties are strongly affected by this structural modification. Moreover, quantum chemistry calculations have allowed to rationalize our experimental observations and, noticeably, to evidence an oxidative quenching process in presence of chlorobenzene, which enhances their reactivity.
Monthly Archives: March 2024
In situ Tracking the Constrained Reconstruction of Cu3Pd@SiO2 Nanoparticles Driven by Redox Atmospheres
Endowed with flexible surface coordination and synergetic electronic status, bimetallic particles serve as promising heterogeneous catalysts as their microstructures evolved sensitively to the treatment atmospheres, whereas knowledge of dynamic manners is less. Herein, utilizing environmental transmission electron microscopy (ETEM), the reconstructions of Cu3Pd particles in oxidation/reduction atmospheres were explored at atomic scale. Specifically, bare Cu3Pd particles went through a phase separation of CuO and PdO during in situ oxidation, and subsequent agglomeration after H2 reduction. While protected in a silica shell, the confined Cu3Pd particles were oxidized into Cu1.5Pd0.5O2 phase after air calcination and subsequently restructured into versatile configurations during reduction. Specifically, hollow Cu3Pd alloy architecture with Pd enriched layer near surface as reduced at 200 oC. Further rising 400 to 600 oC, it yielded disordered Cu3Pd alloys with slightly Pd atoms enrichment at outmost surface. The dynamical behaviors of single Cu1.5Pd0.5O2 particle during in situ reduction have been visualized in ETEM, wherein a series of deformation, elongation and rotation is involved during the hollow architecture firstly formation, and then vanished into a Cu3Pd solid solution nanoparticle. The tunable microstructures of Cu3Pd@SiO2 driven by redox atmospheres demonstrate efficient approach for precisely regulating the chemical environments of constrained bimetallic nanocatalysts.
Conversion of β‐1,6‐glucans to gentiobiose using an endo‐β‐1,6‐glucanase PsGly30A from Paenibacillus sp. GKG
A plethora of di- and oligosaccharides isolated from the natural sources are used in food and pharmaceutical industry. An enzymatic hydrolysis of fungal cell wall β-glucans is a good alternative to produce the desired oligosaccharides with different functionalities, such as the flavour enhancer gentiobiose. We have previously identified PsGly30A as a potential yeast cell wall degrading β-1,6-glycosidase. The aim of this study is to characterise the PsGly30A enzyme, a member of the GH30 family, and to evaluate its suitability for the production of gentiobiose from β-1,6-glucans. An endo-β-1,6-glucanase PsGly30A encoding gene from Paenibacillus sp. GKG has been cloned and overexpressed in Escherichia coli. The recombinant enzyme has been active towards pustulan and yeast β-glucan, but not on laminarin from the Laminaria digitata, confirming the endo-β-1,6-glucanase mode of action. The PsGly30A shows the highest activity at pH 5.5 and 50°C. The specific activity of PsGly30A on pustulan (1262±82 U/mg) is among the highest reported for GH30 β-1,6-glycosidases. Moreover, gentiobiose is the major reaction product when pustulan, yeast β-glucan or yeast cell walls has been used as a substrate. Therefore, PsGly30A is a promising catalyst for valorisation of the yeast-related by-products.
Reversible Influence of Hemipiperazine Photochromism on the Early Development of Zebrafish Embryo
This study explores the potential of controlling organismal development with light by using reversible photomodulation of activity in bioactive compounds. Specifically, our research focuses on plinabulin 1, an inhibitor of tubulin dynamics that contains a photochromic motif called hemipiperazine. The two isomeric forms, Z-1 and E-1, can partially interconvert with light, yet show remarkable thermal stability in darkness. The Z-isomer exhibits higher cytotoxicity due to stronger binding to α-tubulin's colchicine site. The less toxic E-1 form, considered a "pro-drug", can be isolated in vitro and stored. Upon activation by blue or cyan light, it predominantly generates the more toxic Z-1 form. Here we demonstrate that 1 can effectively photomodulate epiboly, a critical microtubule-dependent cell movement during gastrulation in zebrafish embryos. This research highlights the potential of photomodulation for precise and reversible control of cellular activities and organismal development.
Synthesis and Macrodomain Binding of Gln‐carba‐ADPr‐peptide
Mono-ADP-ribosylation is a dynamic post-translational modification (PTM) with important roles in cell signalling. This modification occurs on a wide variety of amino acids, and one of the canonical modification sites within proteins is the side chain of glutamic acid. Given the transient nature of this modification (acylal linkage) and the high sensitivity of ADP-ribosylated glutamic acid, stabilized isosteres are required for structural and biochemical studies. Here, we report the synthesis of a mimic of ADP-ribosylated peptide derived from histone H2B that contains carba-ADP-ribosylated glutamine as a potential mimic for Glu-ADPr. We synthesized a cyclopentitol-ribofuranosyl derivative of 5'-phosphoribosylated Fmoc-glutamine and used this in the solid-phase synthesis of the carba-ADPr-peptide mimicking the ADP-ribosylated N-terminal tail of histone H2B. Binding studies with isothermal calorimetry demonstrate that the macrodomains of human MacroD2 and TARG1 bind to carba-ADPr-peptide in the same way as ADPr-peptides containing the native ADP-riboside moiety connected to the side chain of glutamine in the same peptide sequence.
Photochemical Carbocatalysis: Fullerene‐, Carbon nanotube‐ or Graphene‐based Metal‐free Photocatalysts for Organic Transformations
Synthetic photochemistry is a research field, where organic transformations are promoted by the presence of photoactive species, under light irradiation. In particular, the sub-field of photo-organocatalysis, where organic molecules are used as photocatalysts, has been launched as a “green” and sustainable approach. Carbon allotrope nanostructures (CANs) and their derivatives exhibit unique photophysical and photochemical properties, which have been exploited for the preparation of efficient metal-free and sustainable photocatalytic systems. This review summarizes the progress on the field of photochemical carbocatalysis, presenting the achievements by fullerene-, carbon nanotube- and graphene-based nanomaterials. Additionally, future prospects for CAN-based nanomaterials as photochemical promoters for organic transformations are also mentioned.
Bi site doped Ferroelectric BiFe0.95Mn0.05O3 Nanoparticles for Hydrogen Evolution Reaction
The investigation delves into the functionality exhibited by ferroelectric BiFe0.95Mn0.05O3 (BFM) nanoparticles (NPs) concerning the hydrogen evolution reaction (HER). The electrocatalytic activity of BFM NPs undergoes a transformative shift as a consequence of mono-, di-, and tri-valent cation substitution. Notably, the strategic engineering of doping at the Bi site within BFM NPs yields a remarkable outcome, namely the conspicuous reduction of the kinetic overpotential prerequisite for HER. This diminished overpotential in doped BFM NPs arises from the confluence of multifarious factors: diminished charge transfer resistance, augmented specific surface area, a discernible distribution of pore sizes ranging from narrow to broad, particles endowed with a shape boasting abundant active facets, and the integration of dopants as novel active sites on the surface. Furthermore, the presence of surface defects, oxygen vacancies, and amplified microstrain within doped BFM NPs contributes to the reduction in overpotential.
New energetic 1,2,4‐triazole‐nitrofuroxan hybrids
New energetic (1,2,4-triazolyl)furoxans were synthesized and their physicochemical properties were estimated. The obtained results serve as an evidence that an alliance of 1,2,4-triazole and furoxan rings may constitute a suitable platform for the construction of promising energetic materials.
Abstract
New promising energetic materials comprised of 1,2,4-triazole and furoxan rings and bearing explosophoric nitro group were rationally designed and synthesized. All newly prepared compounds were thoroughly characterized and their physicochemical properties were estimated. In the newly synthesized series, (1,2,4-triazolyl)furoxan 4 is completely insensitive to impact and friction and possesses good detonation performance (D = 8.4 km s−1; P = 33 GPa) enabling its further exploration as a promising high-energy material.
Recent developments in synthetic strategies and pharmacological outcomes of synthetic xanthine oxidase inhibitors: A comprehensive review
This methodological study highlighted potential xanthine oxidase inhibitors and their therapeutic significance, with an emphasis on those that have the greatest therapeutic efficacy and the fewest side effects.
Abstract
Xanthine oxidase is an important enzyme in purine metabolism that converts hypoxanthine to xanthine and subsequently xanthine to uric acid. Its elevated levels result in an abnormal accumulation of uric acid that results in gout and other pathological conditions, which makes it a prime target for the management of gout. Considering this, numerous reports have been published by the various research groups across the globe focusing on the development of effective xanthine oxidase inhibitors. On that ground, numerous review articles are also available describing the pharmacological outputs of these reports, but a composition highlighting the synthetic strategies used in these research works is still missing. This review will focus on various synthetic strategies adopted by different research groups in developing xanthine oxidase inhibitors with their pharmacological outcomes, along with structure activity relationships. This review will help researchers and pharmaceutical chemists in the design and development of new xanthine oxidase inhibitor leads that are highly efficient and have fewer side effects than existing ones.
Investigation of advanced biological properties of carbon, carbon‐boron quantum dots, and copper (II) phthalocyanine nanoconjugates
Non-peripherally substituted copper (II) phthalocyanine was non-covalently attached to carbon and carbon-boron quantum dots. Various biological assessments were applied to these compounds. Conjugates exhibited high antidiabetic activities at 200 mg/L. Also, compounds showed significant DNA nuclease activity. The most efficient MIC value was obtained against Enterococcus hirae and Enterococcus feacalis. This MIC value was further decreased after photodynamic therapy. Inhibition of microbial cell viability was obtained as 100% for all compounds. In addition, compounds exerted perfect biofilm inhibitory effects.
Non-peripherally, glycerol terminal groups substituted copper (II) phthalocyanine were non-covalently (electrostatic and/or π–π interaction) attached to carbon (CQD) and carbon-boron quantum dots (CBQD) to form QDs-Pc nanoconjugate systems. Synthesized novel phthalocyanine compounds and QDs-Pc conjugate systems were characterized using different spectroscopic techniques. Various biological assessments were applied to newly synthesized compounds. Conjugates 4 and 5 had a maximal free radical scavenging activity of 71.3% and 68.1% at a 100 mg/L concentration. Compounds exhibited high antidiabetic activities at 200 mg/L. Also, compounds showed significant DNA nuclease activity at all tested concentrations. The most efficient MIC value was obtained as 4 mg/L against Enterococcus hirae and Enterococcus feacalis. This MIC value was further decreased after photodynamic therapy, and it was observed that the antimicrobial effects of the compounds increased. Inhibition of microbial cell viability was obtained as 100% for all compounds. In addition, compounds exerted perfect biofilm inhibitory effects.