Enhanced Laccase Activity and Stability as Crosslinked Enzyme Aggregates on Magnetic Copper Ferrite Nanoparticles for Biotechnological Processes

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Enhanced Laccase Activity and Stability as Crosslinked Enzyme Aggregates on Magnetic Copper Ferrite Nanoparticles for Biotechnological Processes

This work demonstrates the facile and cost-effective synthesis of magnetic crosslinked laccase aggregates (m-CLEAS) on CuFe2O4. m-CLEAS showed high enzyme loading, improved catalytic performance and thermal stability with exceptional storage stability than free enzyme and CLEAS. The results highlight the promise of m-CLEAS for green industrial processes.


Abstract

Highly stable and reusable magnetic crosslinked enzyme aggregates (m-CLEAS) of laccase are synthesized with simultaneous improved enzymatic activity. Magnetic copper ferrite nanoparticles (CFNPs) were synthesized by solvothermal procedure with an average size of ~8 nm. The nanometric m-CLEAS were formed by co-aggregation of enzyme with CFNPs and crosslinked using glutaraldehyde. Different mass ratios of CFNPs:Laccase were assayed (1 : 2, 1 : 3, and 1 : 6), where 1 : 6 resulted in the highest activity recovery (97 %). The m-CLEAS showed an average size of ~239 nm, ~24 % enzyme immobilization efficiency, and loading as high as 1.75 g of protein per g of support. As expected, m-CLEAS oxidized the substrate with a higher transformation rate (k cat) and catalytic efficiency (k cat/Km) than the free enzyme. m-CLEAS showed superior storage and thermostability compared to free enzyme and non-magnetic CLEAS. In particular, the m-CLEAS showed ~150 % and ~100 % residual activity after 30 days of storage at 4 °C and room temperature, respectively. Furthermore, m-CLEAS showed good recyclability, retaining ~78 % and ~54 % laccase activity after 5 and 10 cycles of reuse, respectively. This work highlights the facile and cost-effective synthesis of nanometric m-CLEAS with exceptional storage stability and simultaneously improved laccase activity, making them suitable for a range of green industrial processes.

Cover Feature: Bottom‐up Synthesis of Nanosheets at Various Interfaces (ChemPlusChem 10/2023)

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Cover Feature: Bottom-up Synthesis of Nanosheets at Various Interfaces (ChemPlusChem 10/2023)

The cover feature image shows the industrial production of nanosheets. First, the ingredients are poured into the continuously stirred tank reactor. The reacted solution is separated at the next tank. The suspension of nanosheets is centrifuged, and the obtained nanosheets are packed into vessels as concentrated suspensions. The practical use of nanosheets requires the development of a facile and versatile synthesis method controlling the size of nanosheets at a low cost to be scaled up. More information can be found in the Review by Yoshiaki Uchida and co-workers.


Modular Synthesis of Phosphino Hydrazones and Their Use as Ligands in a Palladium‐Catalysed Cu‐Free Sonogashira Cross‐Coupling Reaction

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Modular Synthesis of Phosphino Hydrazones and Their Use as Ligands in a Palladium-Catalysed Cu-Free Sonogashira Cross-Coupling Reaction

Unlocking the potential of phosphino hydrazones: Harnessing the power of hydrazone condensation to synthesise phosphino hydrazone ligands from 3-(diphenylphosphino)propanal and commercially available aryl hydrazines and studying their palladium complexes for Cu-free Sonogashira cross-coupling reaction. Read more about the story behind the cover in the Cover Profile and about the research itself (DOI: 10.1002/cplu.202300163).


Abstract

Invited for this month's cover is the group of Evamarie Hey-Hawkins at Leipzig University. The cover picture shows the three different bonding modes (mono-, bi- and tridentate) of the modular ligand towards palladium(II) or platinum(II), illustrated with Winston who kindly served as the model. The cat has three binding sites (mouth, front paws and hind paws = P, N and pyridine) to bind the metal dichloride fragment. When all three are used in a tridentate bonding mode, one chlorido ligand is cleaved off. Cover design by Dr. Christoph Selg. More information can be found in the Research Article by Evamarie Hey-Hawkins and co-workers.

Sulfoxonium Ylides as Carbene Precursors in Rhodium‐Catalyzed Sommelet‐Hauser Rearrangement for the Synthesis of S/Se‐Containing Compounds

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Sulfoxonium Ylides as Carbene Precursors in Rhodium-Catalyzed Sommelet-Hauser Rearrangement for the Synthesis of S/Se-Containing Compounds

Sulfoxonium ylides as the safe carbene precursors are firstly used in Sommelet-Hauser rearrangement reactions for the synthesis of sulfur/selenium-containing compounds. The present reaction highlights the advantages of mild condition and broad substrate scope.


Abstract

Rhodium-catalyzed Sommelet-Hauser rearrangement derived from α-thioesters/α-selenoesters and sulfoxonium ylides has been developed for the synthesis of various sulfur/selenium-containing ortho-substituted aromatic compounds in medium to excellent yields (39 examples; up to 97 %). Sulfoxonium ylides as the safe carbene precursors are firstly used in Sommelet-Hauser rearrangement reactions, which is superior to traditional diazo compounds. The present reaction has the advantages of mild condition, safety and broad substrate scope, which afford a unique method for the synthesis of sulfur/selenium-containing compounds with a tertiary carbon center.

A Biomimetic Stereoselective Approach to Euolutchuol C and Its Structural Assignment

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A Biomimetic Stereoselective Approach to Euolutchuol C and Its Structural Assignment

The first stereoselective total synthesis of euolutchuol C is demonstrated using a biomimetic cationic polyene cyclization, and its absolute structure is established. Four potential stereoisomers of euolutchuol C were synthesized to confirm the structure as an aromatic abietane diterpenoid consisting of a 15(S)-stereogenic center. Asymmetric Sharpless dihydroxylation was employed to build the chiral epoxide, while CBS-reduction was utilized to obtain enantiomerically pure benzylic alcohols. A convergent approach is used to synthesize euolutchuol C in seven longest linear steps resulting in an overall yield of 23 %.


Abstract

The first stereoselective total synthesis of euolutchuol C using a biomimetic cationic polyene cyclization is demonstrated, and its absolute structure has been established. Four potential stereoisomers of euolutchuol C were synthesized to confirm the structure as an aromatic abietane diterpenoid consisting of 15(S)-stereogenic center. Asymmetric Sharpless dihydroxylation was employed to construct the chiral epoxide, while CBS-reduction was utilized for enantiomerically pure benzylic alcohols. A convergent approach is used to synthesize euolutchuol C in seven longest linear steps to give an overall yield of 23 %.

Facile Stereoselective Synthesis and Structural Study of Camphor‐ and Fenchone‐Based Spirocyclic 1,3,4‐Oxadiazolines

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Facile Stereoselective Synthesis and Structural Study of Camphor- and Fenchone-Based Spirocyclic 1,3,4-Oxadiazolines

For the first time, an effective method for the synthesis of spirocyclic camphor- and fenchone-based 1,3,4-oxadiazolines has been developed. The influence of the terpene scaffold on the reaction stereoselectivity was studied. The proposed method allows obtaining of spirocyclic products with a wide structural diversity, stereoselectively and in good yields.


Abstract

For the first time, an effective method for the synthesis of spirocyclic camphor- and fenchone-based 1,3,4-oxadiazolines has been developed. The influence of the molecular structure of the terpene substrate on the reaction stereoselectivity was studied. The structural features of the target products were studied using NMR spectroscopy and X-ray diffraction analysis. The proposed method allows obtaining of spirocyclic products with a wide structural diversity, stereoselectively and in good yields.

Direct Access to 1,3‐Oxathiolan‐5‐ones through (3+2)‐Cycloaddition of Thioketones and Acetylenedicarboxylic Acid

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Direct Access to 1,3-Oxathiolan-5-ones through (3+2)-Cycloaddition of Thioketones and Acetylenedicarboxylic Acid

1,3-Oxathiolan-5-ones are a hitherto very poorly studied class of sulfur heterocycles some of which have been shown to be important precursors for HIV drugs or bioactive, anticarcinogenic compounds. We have developed a novel and effective process for the direct generation of this structural motif in a (3+2)-cycloaddition of thioketones and acetylenedicarboxylic acid. The cycloadducts were obtained with complete regioselectivity and up to >99 % yield. The heterocyclic motif was confirmed by X-ray diffraction analysis.


Abstract

Herein, we report a novel protocol for the direct synthesis of 1,3-oxathiolan-5-ones based on the (3+2)-cycloaddition between thioketones and acetylenedicarboxylic acid. The products were obtained in a one-pot reaction within short reaction times and in typically very good yields. The product structure was confirmed by X-ray diffraction analysis.

Reversible Acid‐Base Responsive Fluorescence Changes of Solutions and Crystals Based on Anthracenyl Pyridyl Derivatives

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Reversible Acid-Base Responsive Fluorescence Changes of Solutions and Crystals Based on Anthracenyl Pyridyl Derivatives

Organic molecules AN9P and AN2P exhibit fast reversible fluorescence evolutions upon alternate acid and base stimuli in solutions and as crystals.


Abstract

Organic compounds that can respond to external stimuli and exhibit fluorescence changes have drawn increasing attention recently because of their potential applications in intelligent displays, optical data storage, anticounterfeiting, bioimaging, and sensors. Herein, we have synthesized two new organic compounds based on frameworks of anthracene and pyridine groups: 4-(anthracen-9-yl) pyridine (AN9P) and 4-(anthracen-2-yl) pyridine (AN2P). Both compounds, in solution and solid state, including polycrystals and single crystals, display reversible fluorescence transformations under alternate acid and base treatments. AN9P and AN2P solutions could be regulated to emit white-light luminescence. The photoluminescence of the AN9P and AN2P polycrystals showed fast fluorescence changes with wide ranges (>300 nm) upon alternate acid and base stimuli and still exhibited remarkable fluorescence emission with almost no attenuation after 15 cycles of the reversible process. Both experimental and computational results suggested that the heteroatom nitrogen in the AN9P and AN2P molecules significantly influenced the intra- and intermolecular electronic interactions during the reversible protonation and deprotonation processes, resulting in changes in their frontier molecular orbitals and fluorescence emission characteristics. Our results provide a new facile approach to design molecular structures that realize highly dynamic photoluminescence changes in both liquid solution and solid crystal.

Rhodium(I) PNN Pincer Complexes with Proton‐responsive Ligands: Synthesis, Characterisation, and Catalytic Dehydrocoupling of Amine Boranes

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Rhodium(I) PNN Pincer Complexes with Proton-responsive Ligands: Synthesis, Characterisation, and Catalytic Dehydrocoupling of Amine Boranes

Pyrazole-based PNN(H) RhI complexes are active catalysts for the dehydrocoupling of amine boranes to produce cyclic oligomers. Efficient dehydrohalogenation of the Rh chloride precursor complex and ligand deprotonation are essential for the realization of high catalytic activity.


Abstract

Coordination of a pyridine-pyrazole-based PNN(H) ligand to RhI produces a family of neutral (1) and cationic (2Cl) RhI complexes. Deprotonation of the parent Rh chloride complex with LiNiPr2 results in formation of a dinuclear LiCl bridged species 3 bearing a pyrazolate fragment. Complexes 1, 2Cl and 3 were tested as precatalyst for the dehydrocoupling of amine boranes. All complexes studied show activity for the formation of cyclic oligomers with N-methylcyclotriborazane as the main product. Base activation of the neutral Rh chloride complex 1 produces catalyst systems that are significantly more active than the parent system, suggesting that dehydrohalogenation of the Rh chloride precatalyst 1 is one of the key steps for catalyst formation.

Medicinal‐Chemistry‐Driven Approach to 2‐Substituted Benzoxazole–Estradiol Chimeras: Synthesis, Anticancer Activity, and Early ADME Profile

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Medicinal-Chemistry-Driven Approach to 2-Substituted Benzoxazole–Estradiol Chimeras: Synthesis, Anticancer Activity, and Early ADME Profile

A series of diversely substituted benzoxazole–estradiol chimeras were prepared and characterized based on critical physicochemical parameters. The performance of the compounds to inhibit cell proliferation was tested on human cancer cell lines and non-cancerous cells. Pharmacological tests (IC50 values, cancer cell selectivity, apoptosis-triggering features) and LLE metric revealed that the anticancer activity of some derivatives was stronger than or similar to that of 2-methoxyestradiol and cisplatin.


Abstract

The efficient synthesis of novel estradiol-based A-ring-fused oxazole derivatives, which can be considered as benzoxazole-steroid domain-integrated hybrids containing a common benzene structural motif, is described. The target compounds were prepared from steroidal 2-aminophenol precursors by heterocycle formation or functional group interconversion (FGI) strategies. According to 2D projection-based t-distributed stochastic neighbor embedding (t-SNE), the novel molecules were proved to represent a new chemical space among steroid drugs. They were characterized based on critical physicochemical parameters using in silico and experimental data. The performance of the compounds to inhibit cell proliferation was tested on four human cancer cell lines and non-cancerous cells. Further examinations were performed to reveal IC50 and lipophilic ligand efficiency (LLE) values, cancer cell selectivity, and apoptosis-triggering features. Pharmacological tests and LLE metric revealed that some derivatives, especially the 2-(4-ethylpiperazin-1-yl)oxazole derivative exhibit strong anticancer activity and trigger the apoptosis of cancer cells with relatively low promiscuity risk similarly to the structurally most closely-related and intensively studied anticancer agent, 2-methoxy-estradiol.