Antifungal Activity of Cadinane‐Type Sesquiterpenes from Eupatorium adenophorum against Wood‐Decaying Fungi

Posted on 21 September 2023 by

Abstract

The present study aimed to evaluate the antifungal activities of Eupatorium adenophorum against four strains of wood-decaying fungi, including Inonotus hispida, Inonotus obliquus, and Inonotus cuticularis. Bioguided isolation of the methanol extract of E. adenophorum by silica gel column chromatography and high-performance liquid chromatography afforded six cadinane-type sesquiterpenes. Their structures were identified by nuclear magnetic resonance and MS analyses. According to the antifungal results, the inhibition rate of the compound was between 59.85 % and 77.98 % at a concentration of 200 μg/mL. The EC₅₀ values ranged from 74.5 to 187.4 μg/mL.

A Graphene Oxide‐Supported PdCu Catalyst for Enhanced Electrochemical Synthesis of Ammonia

Posted on 21 September 2023 by

A PdCu alloy catalyst loaded on a graphene oxide carrier was prepared through a simple liquid phase reduction method which greatly enhanced the catalytic performance with an ammonia yield of 1.62 mg h⁻¹cm⁻² and Faradaic efficiency of 38.2 % under the nitrate reduction ammonia synthesis (NO₃RR) reaction at an overpotential of −0.4 V. For the nitrogen reduction ammonia, the ammonia yield was 20.83 μg h⁻¹ cm⁻² with a Faradaic efficiency of 3.8 %.

Abstract

The conventional Haber-Bosch method for the ammonia synthesis process requires high temperature and pressure. Electrochemical synthesis of ammonia, an emerging ammonia synthesis technology, is a promising approach for sustainable ammonia production that is energy-efficient and free of greenhouse gas emissions. The design and development of high-performance catalysts are the keys to promoting the sustainable ammonia production process. This work synthesized a PdCu alloy catalyst loaded on a graphene oxide carrier through a simple liquid phase reduction method. Which greatly enhanced the catalytic performance with an ammonia yield of 1.62 mg h⁻¹cm⁻² and Faradaic efficiency of 38.2 % under the nitrate reduction ammonia synthesis (NO₃RR) reaction at an overpotential of −0.4 V. For the nitrogen reduction ammonia (NRR), the ammonia yield was 20.83 μg h⁻¹ cm⁻² with a Faradaic efficiency of 3.8 %. This study may provide a new idea for material design and promote ammonia synthesis development under ambient conditions.

Coupled Electrochemical Processes as Versatile Route for Converting Waste Substrates into Value Added Chemical Products

Posted on 21 September 2023 by nChristian M. Pichlern

The conversion of waste substrates into value added chemical products is a promising pathway to implement principles of circular economy in chemical industry and replace fossil feedstocks. To overcome the chemical complexity and heterogenous nature of waste feedstocks coupled processes are ideally suited. Implementing electrochemical steps enhances sustainability and opens novel reaction pathways.

Abstract

There is a strong initiative in chemical industry to replace fossil resources by alternative feedstocks and implement more sustainable production routes for chemicals. Waste feedstocks are especially appealing, considering the principles of circular economy. They exhibit, however, great structural complexity, and it is challenging to convert them into defined chemical products. To still enable the conversion of waste feedstocks into value added chemicals, coupled catalytic processes are a viable solution. A first reaction step transforms the waste substrate into more defined and soluble intermediates which are subsequently converted into value added chemicals, in a second reaction step. Electrochemical reactions are of great interest for such processes, especially in the context of sustainability, as they can be powered by electricity from renewable sources and enable unique chemical transformations. In this review different strategies for converting waste substrates into value added chemicals are addressed by using process couplings including electrochemical reactions. Such coupled processes are of great interest to enable the transformation of chemical industry towards sustainable processes following the principles of circular economy.

Modulating the RAGE‐Induced Inflammatory Response: Peptoids as RAGE Antagonists

Posted on 21 September 2023 by

Peptoids were designed to mimic receptors for advanced glycation end-products (RAGE) ligand amyloid-β (Aβ) and curtail RAGE inflammatory activation. Here, we reveal the nanomolar binding capability of the peptoid-based mimics to RAGE and demonstrate their ability to attenuate lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production as well as reduce upregulation of cell surface RAGE at non-toxic concentrations.

Abstract

While the primary pathology of Alzheimer's disease (AD) is defined by brain deposition of amyloid-β (Aβ) plaques and tau neurofibrillary tangles, chronic inflammation has emerged as an important factor in AD etiology. Upregulated cell surface expression of the receptor for advanced glycation end-products (RAGE), a key receptor of innate immune response, is reported in AD. In parallel, RAGE ligands, including Aβ aggregates, HMGB1, and S100B, are elevated in AD brain. Activation of RAGE by these ligands triggers release of inflammatory cytokines and upregulates cell surface RAGE. Despite such observation, there are currently no therapeutics that target RAGE for treatment of AD-associated neuroinflammation. Peptoids, a novel class of potential AD therapeutics, display low toxicity, facile blood-brain barrier permeability, and resistance to proteolytic degradation. In the current study, peptoids were designed to mimic Aβ, a ligand that binds the V-domain of RAGE, and curtail RAGE inflammatory activation. We reveal the nanomolar binding capability of peptoids JPT1 and JPT1a to RAGE and demonstrate their ability to attenuate lipopolysaccharide-induced pro-inflammatory cytokine production as well as upregulation of RAGE cell surface expression. These results support RAGE antagonist peptoid-based mimics as a prospective therapeutic strategy to counter neuroinflammation in AD and other neurodegenerative diseases.

Rapid On‐Resin N‐Formylation of Peptides as One‐Pot Reaction

Posted on 21 September 2023 by

Fast but not furious. A rapid on-resin N-formylation protocol for peptides was developed using formic acid, acetic anhydride, pyridine, and DMF. This method is simple in execution and provides near quantitative yield independent of peptide length and sequence.

Abstract

N-formylation is a common pre- and post-translational modification of the N-terminus or the lysine side chain of peptides and proteins that plays a role in the initiation of immune responses, gene expression, or epigenetics. Despite its high biological relevance, protocols for the chemical N-formylation of synthetic peptides are scarce. The few available methods are elaborate in their execution and the yields are highly sequence-dependent. We present a rapid, easy-to-use one-pot procedure that runs at room temperature and can be used to formylate protected peptides at both the N-terminus and the lysine side chain on the resin in near-quantitative yields. Only insensitive, storage-stable standard chemicals – formic acid, acetic anhydride, pyridine and DMF – are used. Formylation works for both short and long peptides of up to 34 amino acids and over the spectrum of canonical amino acids.

Synthesis of Naphthalene‐ and Phenanthrene‐Fused Smaragdyrins and Their BF2 Complexes

Posted on 21 September 2023 by

Naphthalene- and phenanthrene-fused [22]smaragdyrins BF₂ complexes and their [20]smaragdyrin free bases are synthesized by Suzuki-Miyaura coupling, Witting-type methoxymethylenation, methanesulfonic acid-catalyzed cyclization reaction, and demetalation. These fused [22]smaragdyrin BF₂ complexes and [20]smaragdyrin free bases show decreased aromatic characters and antiaromatic characters, respectively. These fused compounds exhibit red-shifted and enhanced absorption bands in NIR region.

Abstract

Naphthalene- and phenanthrene-fused [22]smaragdyrin BF₂-complexes were synthesized by 1) Suzuki-Miyaura coupling of β-brominated [22]smaragdyrin BF₂ complexes with 2-formylarylboronates, 2) Witting-type methoxymethylenation of the formyl group, and 3) methanesulfonic acid-catalyzed cyclization reaction. Subsequently these BF₂ complexes were deboronized and oxidized to the corresponding antiaromatic [20]smaragdyrin free bases. The installed fused structures led to decrease of the aromatic characters of the [22]smaragdyrin BF₂ complexes and the antiaromatic characters of the [20]smaragdyrin free bases.

ZnGa2O4 : Cr3+@Calcium Phosphate Nanocomposite with Near‐Infrared Persistent Luminescence and High Stability

Posted on 21 September 2023 by

Shine bright: Persistent luminescent Cr-doped ZnGa₂O₄ (CZGO) is incorporated into an amorphous calcium phosphate (ACP) matrix. Annealing CZGO prior to ACP integration greatly improves its luminescence intensity and duration. Zn²⁺ redistribution from CZGO to ACP is identified, leading to the formation of Zn₃(PO₄)₂ when immersed in water. The nanocomposite exhibits high stability under prolonged X-ray exposure.

Abstract

Persistent luminescence (PersL) is an optical phenomenon which allows for materials to emit luminescence after ceasing excitation. The long-lasting luminescence is ascribed to the presence of trap states, which can be exploited through the introduction of various dopants and post-synthesis treatment. In this study, ZnGa₂O₄ : Cr³⁺ (CZGO), one of the most widely investigated near-infrared-emitting PersL materials, is synthesized in the form of nanoparticles, and incorporated into amorphous calcium phosphate (ACP) to form a luminescent nanocomposite with drug attachment potential. The effects of annealing CZGO in the composite are comparatively studied alongside the composite that contains unannealed CZGO. We find that ACP with annealed CZGO exhibits much higher luminescence intensity and longer PersL duration. The formation of the nanocomposite also results in the redistribution of Zn, and its influence on the composite luminescence intensity and the long-term chemical stability are investigated.

One‐Carbon Homologation of α,β‐Unsaturated Aldehydes: Access to α‐Tertiary β,γ‐Unsaturated Aldehydes

Posted on 21 September 2023 by

An efficient two-step no purification protocol for the synthesis of enolizable α-subtituted β,γ-unsaturated aldehydes is reported. The developed strategy involves two steps, epoxidation and Meinwald rearrangement, to result in a formal one-carbon homologation of α,β-unsaturated aldehydes enabling the insertion of a CHR unit.

Abstract

An efficient protocol for the synthesis of enolizable α-substituted β,γ-unsaturated aldehydes is reported. The developed strategy involves two steps, epoxidation and Meinwald rearrangement, to result in a one-carbon homologation of α,β-unsaturated aldehydes enabling the insertion of a CHR unit.

Dynamic Metal‐ligand Coordination for Fluorescence Color Regulation of Hydrazone‐based Bistable Photoswitches

Posted on 21 September 2023 by

We have successfully achieved dynamic manipulation of fluorescence color (540 nm to 607 nm) and intensity by altering the counterions of zinc complexes and switching the isomer from Z to E.

Abstract

Achieving effective manipulation of emission color in photoresponsive materials is crucial for various advanced photonic applications. In this study, we designed and synthesized a hydrazone compound 1, ethyl (Z)-2-(2-([2,2′:6′,2′′-terpyridin]-4′-yl)hydrazineylidene)-2-(4-(diphenylamino)phenyl)acetate, which possesses a push-pull structure incorporating triphenylamine and terpyridine. The emission intensity of compound 1 can be repeatedly switched “off” and “on” by irradiation with visible light and UV light, which induces the isomerization transition between the Z and E forms. In addition, compound 1 is capable of changing its emission wavelength from 540 nm to 607 nm through coordination with different zinc salts in toluene/CH₂Cl₂ mixture (v : v=1 : 1). Importantly, we have successfully achieved dynamic manipulation of fluorescence color and intensity by altering the counterions of zinc complexes and switching the isomer from Z to E. Moreover, both compound 1 and its zinc complexes demonstrate remarkable photoswitchable properties with different fluorescence colors in the thin films. Finally, these films with various fluorescence colors were used for the production of luminescent tags.

[Fe]‐Hydrogenase, Cofactor Biosynthesis and Engineering

Posted on 21 September 2023 by

[Fe]-hydrogenase contains the FeGP cofactor as the prosthetic group for activation of H₂. HcgA−G are involved in the biosynthesis of the cofactor. Most of the biosynthesis reactions were elucidated by structure-to-function analysis and in vitro biosynthesis. We describe the catalytic function of the Hcg proteins and the possibility of engineering of the FeGP cofactor in redesigned hydride-transfer enzymes.

Abstract

[Fe]-hydrogenase catalyzes the heterolytic cleavage of H₂ and reversible hydride transfer to methenyl-tetrahydromethanopterin. The iron-guanylylpyridinol (FeGP) cofactor is the prosthetic group of this enzyme, in which mononuclear Fe(II) is ligated with a pyridinol and two CO ligands. The pyridinol ligand fixes the iron by an acyl carbon and a pyridinol nitrogen. Biosynthetic proteins for this cofactor are encoded in the hmd co-occurring (hcg) genes. The function of HcgB, HcgC, HcgD, HcgE, and HcgF was studied by using structure-to-function analysis, which is based on the crystal structure of the proteins and subsequent enzyme assays. Recently, we reported the catalytic properties of HcgA and HcgG, novel radical S-adenosyl methionine enzymes, by using an in vitro biosynthesis assay. Here, we review the properties of [Fe]-hydrogenase and the FeGP cofactor, and the biosynthesis of the FeGP cofactor. Finally, we discuss the expected engineering of [Fe]-hydrogenase and the FeGP cofactor.