The Effect of the Reducing Sugars in the Synthesis of Visible-Light-Active Copper(I) Oxide Photocatalyst

In the present work, shape tailored Cu₂O microparticles were synthesized by changing the nature of the reducing agent and studied subsequently. d-(+)-glucose, d-(+)-fructose, d-(+)xylose, d-(+)-galactose, and d-(+)-arabinose were chosen as reducing agents due to their different reducing abilities. The morpho-structural characteristics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS), while their photocatalytic activity was evaluated by methyl orange degradation under visible light (120 min). The results show that the number of carbon atoms in the sugars affect the morphology and particle size (from 250 nm to 1.2 µm), and differences in their degree of crystallinity and photocatalytic activity were also found. The highest activity was observed when glucose was used as the reducing agent.     

A clustering-triggered emission strategy for tunable multicolor persistent phosphorescence

A clustering-triggered emission (CTE) strategy, namely the formation of heterogeneous clustered chromophores and conformation rigidification, for achieving tunable multicolor phosphorescence in single-component compounds is proposed. Non-conventional luminophores comprising just oxygen functionalities and free of π-bonding, i.e., d-(+)-xylose (d-Xyl), pentaerythritol (PER), d-fructose (d-Fru) and d-galactose (d-Gal), were adopted as a simple model system with an explicit structure and molecular packing to address the hypothesis. Their concentrated solutions and crystals at 77 K or under ambient conditions demonstrate remarkable multicolor phosphorescence afterglows in response to varying excitation wavelengths, because of the formation of diverse oxygen clusters with sufficiently rigid conformations. The intra- and inter-molecular O⋯O interactions were definitely illustrated by both single crystal structure analysis and theoretical calculations. These findings shed new light on the origin and simple achievement of tunable multicolor phosphorescence in single-component pure organics, and in turn, have strong implications for the emission mechanism of non-conventional luminophores.

A clustering-triggered emission strategy is proposed to readily realize tunable multicolor afterglows in single-component pure organic compounds.     

Prebiotic access to enantioenriched glyceraldehyde mediated by peptides

A prebiotically plausible route to enantioenriched glyceraldehyde is reported via a kinetic resolution mediated by peptides. The reaction proceeds via a selective reaction between the l-peptide and the l-sugar producing an Amadori rearrangement byproduct and leaving d-glyceraldehyde in excess. Solubility considerations in the synthesis of proline–valine (pro–val) peptides allow nearly enantiopure pro–val to be formed starting from racemic pro and nearly racemic (10%) ee val. (ee = enantiomeric excess = (|d − l|)/(d + l)) Thus enantioenrichment of glyceraldehyde is achieved in a system with minimal initial chiral bias. This work demonstrates synergy between amino acids and sugars in the emergence of biological homochirality.

A prebiotically plausible route to enantioenriched glyceraldehyde is reported via a kinetic resolution mediated by peptides.     

Structure Revision of Isocereulide A,an Isoform of the Food Poisoning Emetic Bacillus cereus Toxin Cereulide

The emetic Bacillus cereus toxin cereulide presents an enormous safety hazard in the food industry, inducing emesis and nausea after the consumption of contaminated foods. Additional to cereulide itself, seven structurally related isoforms, namely the isocereulides A–G, have already been elucidated in their chemical structure and could further be identified in B. cereus contaminated food samples. The newly performed isolation of isocereulide A allowed, for the first time, 1D- and 2D-NMR spectroscopy of a biosynthetically produced isocereulide, revealing results that contradict previous assumptions of an l-O-Leu moiety within its chemical structure. By furthermore applying posthydrolytical dipeptide analysis, amino acid and α-hydroxy acid analysis by means of UPLC-ESI-TOF-MS, as well as MSⁿ sequencing, the structure of previously reported isocereulide A could be corrected. Instead of the l-O-Leu as assumed to date, one l-O-Ile unit could be verified in the cyclic dodecadepsipeptide, revising the structure of isocereulide A to [(d-O-Leu-d-Ala-l-O-Val-l-Val)₂(d-O-Leu-d-Ala-l-O-Ile-l-Val)].     

New Crystalline Salts of Nicotinamide Riboside as Food Additives

NR⁺ is a highly effective vitamin B₃ type supplement due to its unique ability to replenish NAD⁺ levels. While NR⁺ chloride is already on the market as a nutritional supplement, its synthesis is challenging, expensive, and low yielding, making it cumbersome for large-scale industrial production. Here we report the novel crystalline NR⁺ salts, d/l/dl-hydrogen tartrate and d/l/dl-hydrogen malate. Their high-yielding, one-pot manufacture does not require specific equipment and is suitable for multi-ton scale production. These new NR⁺ salts seem ideal for nutritional applications due to their bio-equivalence compared to the approved NR⁺ chloride. In addition, the crystal structures of all stereoisomers of NR⁺ hydrogen tartrate and NR⁺ hydrogen malate and a comparison to the known NR⁺ halogenides are presented.     

Kinetically controlled Ag+-coordinated chiral supramolecular polymerization accompanying a helical inversion

We report kinetically controlled chiral supramolecular polymerization based on ligand–metal complex with a 3 : 2 (L : Ag⁺) stoichiometry accompanying a helical inversion in water. A new family of bipyridine-based ligands (d-L1, l-L1, d-L2, and d-L3) possessing hydrazine and d- or l-alanine moieties at the alkyl chain groups has been designed and synthesized. Interestingly, upon addition of AgNO₃ (0.5–1.3 equiv.) to the d-L1 solution, it generated the aggregate I composed of the d-L1AgNO₃ complex (d-L1 : Ag⁺ = 1 : 1) as the kinetic product with a spherical structure. Then, aggregate I (nanoparticle) was transformed into the aggregate II (supramolecular polymer) based on the (d-L1)₃Ag₂(NO₃)₂ complex as the thermodynamic product with a fiber structure, which led to the helical inversion from the left-handed (M-type) to the right-handed (P-type) helicity accompanying CD amplification. In contrast, the spherical aggregate I (nanoparticle) composed of the d-L1AgNO₃ complex with the left-handed (M-type) helicity formed in the presence of 2.0 equiv. of AgNO₃ and was not additionally changed, which indicated that it was the thermodynamic product. The chiral supramolecular polymer based on (d-L1)₃Ag₂(NO₃)₂ was produced via a nucleation–elongation mechanism with a cooperative pathway. In thermodynamic study, the standard ΔG° and ΔH_e values for the aggregates I and II were calculated using the van''t Hoff plot. The enhanced ΔG° value of the aggregate II compared to that of the formation of aggregate I confirms that aggregate II was thermodynamically more stable. In the kinetic study, the influence of concentration of AgNO₃ confirmed the initial formation of the aggregate I (nanoparticle), which then evolved to the aggregate II (supramolecular polymer). Thus, the concentration of the (d-L1)₃Ag₂(NO₃)₂ complex in the initial state plays a critical role in generating aggregate II (supramolecular polymer). In particular, NO₃⁻ acts as a critical linker and accelerator in the transformation from the aggregate I to the aggregate II. This is the first example of a system for a kinetically controlled chiral supramolecular polymer that is formed via multiple steps with coordination structural change.

The nanoparticles were transformed into the supramolecular polymer as the thermodynamic product, involving a helical inversion from left-handed to right-handed helicity.     

Construction of a chiral artificial enzyme used for enantioselective catalysis in live cells

Nanozymes as a newcomer in the artificial enzyme family have shown several advantages over natural enzymes such as their high stability in harsh environments, facile production on large scale, long storage time, low costs, and higher resistance to biodegradation. However, compared with natural enzymes, it is still a great challenge to design a nanozyme with high selectivity, especially high enantioselectivity. It is highly desirable and demanding to develop chiral nanozymes with high and on-demand enantioselectivity for practical applications. Herein, we present an unprecedented approach to construct chiral artificial peroxidase with ultrahigh enantioselectivity. Inspired by the structure of the natural enzyme horseradish peroxidase (HRP), we have constructed a series of stereoselective nanozymes (Fe₃O₄@Poly(AA)) by using the ferromagnetic nanoparticle (Fe₃O₄ NP) yolk as the catalytic core and amino acid-appended chiral polymer shell as the chiral selector. Among them, Fe₃O₄@Poly(d-Trp) exhibits the highest enantioselectivity. More intriguingly, their enantioselectivity will be readily reversed by replacing d-Trp with l-Trp. The selectivity factor is up to 5.38, even higher than that of HRP. Kinetic parameters, dialysis experiments, and molecular simulations together with activation energy reveal that the selectivity originates from the d-/l-Trp appended polymer shell, which can result in better affinity and catalytic activity to d-/l-tyrosinol. The artificial peroxidases have been used for asymmetric catalysis to prepare enantiopure d- or l-enantiomers. Besides, by using fluorescent labelled FITC-tyrosinol_L and RhB-tyrosinol_D, the artificial peroxidases can catalyze green or red fluorescent chiral tyrosinol to selectively label live yeast cells among yeast, S. aureus, E. coli and B. subtilis bacterial cells. This work opens a new avenue for better design of stereoselective artificial enzymes.

A yolk–shell stereoselective nanozyme is designed with a chiral selector. Nanozyme with D-/L-tryptophan possesses high selectivity towards D-/L-tyrosinol and can catalyze chiral tyrosinol to selectively label live yeast cells.     

Possible Participation of Ionotropic Glutamate Receptors and l-Arginine-Nitric Oxide-Cyclic Guanosine Monophosphate-ATP-Sensitive K+ Channel Pathway in the Antinociceptive Activity of Cardamonin in Acute Pain Animal Models

The perception of pain caused by inflammation serves as a warning sign to avoid further injury. The generation and transmission of pain impulses involves various pathways and receptors. Cardamonin isolated from Boesenbergia rotunda (L.) Mansf. has been reported to exert antinociceptive effects in thermal and mechanical pain models; however, the precise mechanism has yet to be examined. The present study investigated the possible mechanisms involved in the antinociceptive activity of cardamonin on protein kinase C, N-methyl-d-aspartate (NMDA) and non-NMDA glutamate receptors, l-arginine/cyclic guanosine monophosphate (cGMP) mechanism, as well as the ATP-sensitive potassium (K⁺) channel. Cardamonin was administered to the animals intra-peritoneally. Present findings showed that cardamonin significantly inhibited pain elicited by intraplantar injection of phorbol 12-myristate 13-acetate (PMA, a protein kinase C activator) with calculated mean ED₅₀ of 2.0 mg/kg (0.9–4.5 mg/kg). The study presented that pre-treatment with MK-801 (NMDA receptor antagonist) and NBQX (non-NMDA receptor antagonist) significantly modulates the antinociceptive activity of cardamonin at 3 mg/kg when tested with glutamate-induced paw licking test. Pre-treatment with l-arginine (a nitric oxide precursor), ODQ (selective inhibitor of soluble guanylyl cyclase) and glibenclamide (ATP-sensitive K⁺ channel inhibitor) significantly enhanced the antinociception produced by cardamonin. In conclusion, the present findings showed that the antinociceptive activity of cardamonin might involve the modulation of PKC activity, NMDA and non-NMDA glutamate receptors, l-arginine/nitric oxide/cGMP pathway and ATP-sensitive K⁺ channel.     

Identification of the peptide epimerase MslH responsible for d-amino acid introduction at the C-terminus of ribosomal peptides

A lasso peptide MS-271 is a ribosomally synthesized and post-translationally modified peptide (RiPP) consisting of 21 amino acids with a d-tryptophan (Trp) at its C terminus. The presence of d-amino acids is rare in RiPPs and few mechanisms of d-amino acid introduction have been characterized. Here, we report the identification of MslH, previously annotated as a hypothetical protein, as a novel epimerase involved in the post-translational epimerization of the C-terminal Trp residue of the precursor peptide MslA. MslH is the first epimerase that catalyzes epimerization at the C_α center adjacent to a carboxylic acid in a cofactor-independent manner. We also demonstrate that MslH exhibits broad substrate specificity toward the N-terminal region of the core peptide, showing that MslH-type epimerases offer opportunities in peptide bioengineering.

The biosynthesis of d-tryptophan containing lasso peptide MS-271 involves the epimerization of a ribosomal peptide MslA catalyzed by a novel class of metal- and cofactor-independent peptide epimerase MslH.     

Self-assembly of cyclic hexamers of γ-cyclodextrin in a metallosupramolecular framework with d-penicillamine

Cyclodextrins are widely used cyclic oligosaccharides of d-glucose whose hydrophilic exterior is covered by hydroxyl groups and whose hydrophobic interior is surrounded by lipophilic moieties. Because of this structural feature, cyclodextrin molecules commonly aggregate into dimensional structures via intermolecular hydrogen bonds, and their aggregation into closed oligomeric architectures has been achieved only via the attachment of functional substituent groups to the cyclodextrin rings. Here, we report the first structurally characterized self-assembly of non-substituted γ-cyclodextrin molecules into cyclic hexamers, which was realized in a chiral coordination framework composed of complex-anions with d-penicillamine rather than l- or dl-penicillamine. The self-assembly is accompanied by the 3D-to-2D structural transformation of porous coordination frameworks to form helical hexagonal cavities that accommodate helical γ-cyclodextrin hexamers. This finding provides new insight into the development of cyclodextrin chemistry and host–guest chemistry based on chiral recognition and crystal engineering processes.

The complex anions with d-penicillamine are organized into a 3D porous framework that allows the inclusion of γ-CD. The inclusion is accompanied by the 3D-to-2D transformation of porous frameworks so as to accept cyclic hexamers of γ-CD.     

Enantioselective and Synergistic Herbicidal Activities of Common Amino Acids Against Amaranthus tricolor and Echinochloa crus-galli

Amino acids have a wide range of biological activities, which usually rely on the stereoisomer presented. In this study, glycine and 21 common α-amino acids were investigated for their herbicidal property against Chinese amaranth (Amaranthus tricolor L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). Both d- and l-isomers, as well as a racemic mixture, were tested and found that most compounds barely inhibited germination but moderately suppressed seedling growth. Various ratios of d:l-mixture were studied and synergy between enantiomers was found. For Chinese amaranth, the most toxic d:l-mixtures were at 3:7 (for glutamine), 8:2 (for methionine), and 5:5 (for tryptophan). For barnyard grass, rac-glutamine was more toxic than the pure forms; however, d-tryptophan exhibited greater activity than racemate and l-isomer, indicating the sign of enantioselective toxicity. The mode of action was unclear, but d-tryptophan caused bleaching of leaves, indicating pigment synthesis of the grass was inhibited. The results highlighted the enantioselective and synergistic toxicity of some amino acids, which relied upon plant species, chemical structures, and concentrations. Overall, our finding clarifies the effect of stereoisomers, and provides a chemical clue of amino acid herbicides, which may be useful in the development of herbicides from natural substances.     

Synthesis and Antiproliferative Evaluation of 2-Deoxy-N-glycosylbenzotriazoles/imidazoles

A series of 2-deoxy-2-iodo-α-d-mannopyranosylbenzotriazoles was synthesized using the benzyl, 4,6-benzylidene and acetyl protected D-glucal in the presence of N-iodosuccinimide (NIS). Subsequent removal of the iodine at the C-2 position using tributyltin hydride under free radical conditions afforded the 2-deoxy-α-d-glucopyranosylbenzotriazoles in moderate to high yields. This method was extended to the preparation of substituted 2-deoxy-β-d-glucopyranosylimidazoles as well. The stereoselectivity of the addition reaction and the effect of the protecting group and temperature on anomer distribution of the benzotriazole series were also investigated. The anticancer properties of the newly synthesized compounds were evaluated in a series of viability studies using HeLa (human cervical adenocarcinoma), human breast and lung cancer cell lines. The N-[3,4,6-tri-O-benzyl-2-deoxy-α-d-glucopyranosyl]-1H-benzotriazole and the N-[3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl]-2H-benzotriazole were found to be the most potent cancer cell inhibitors at 20 µM concentrations across all four cell lines.     

Equilibrium and Kinetic Study of l- and d-Valine Adsorption in Supramolecular-Templated Chiral Mesoporous Materials

Adsorption kinetic studies are conducted to investigate the potential to use chiral mesoporous materials nanoporous guanosine monophosphate material-1 (NGM-1) and nanoporous folic acid material-1 (NFM-1) for the enantiomeric separation of l- and d-valine. A pseudo-second-order (PSO) kinetic model is applied to test the experimental adsorption equilibrium isotherms, according to both the Langmuir and Freundlich models and the characteristic parameters for each model are determined. The calcined versions of both NGM-1 and NFM-1 fit the Langmuir model with maximum sorption capacities of 0.36 and 0.26 g/g for the preferred adsorption enantiomers, d-valine and l-valine, respectively. Experimental results and the analysis of adsorption models suggest a strong adsorbate–adsorbent interaction, and the formation of a monolayer of tightly packed amino acid on the internal mesopore surface for the preferred enantiomers.     

Nitrogenous Compounds from the Antarctic Fungus Pseudogymnoascus sp. HSX2#-11

The species Pseudogymnoascus is known as a psychrophilic pathogenic fungus which is ubiquitously distributed in Antarctica. While the studies of its secondary metabolites are infrequent. Systematic research of the metabolites of the Antarctic fungus Pseudogymnoascus sp. HSX2#-11 led to the isolation of one new pyridine derivative, 4-(2-methoxycarbonyl-ethyl)-pyridine-2-carboxylic acid methyl ester (1), together with one pyrimidine, thymine (2), and eight diketopiperazines, cyclo-(dehydroAla-l-Val) (3), cyclo-(dehydroAla-l-Ile) (4), cyclo-(dehydroAla-l-Leu) (5), cyclo-(dehydroAla-l-Phe) (6), cyclo-(l-Val-l-Phe) (7), cyclo-(l-Leu-l-Phe) (8), cyclo-(l-Trp-l-Ile) (9) and cyclo-(l-Trp-l-Phe) (10). The structures of these compounds were established by extensive spectroscopic investigation, as well as by detailed comparison with literature data. This is the first report to discover pyridine, pyrimidine and diketopiperazines from the genus of Pseudogymnoascus.     

Synthesis,structure, and reactivity of uranium(vi) nitrides

Uranium nitride compounds are important molecular analogues of uranium nitride materials such as UN and UN₂ which are effective catalysts in the Haber–Bosch synthesis of ammonia, but the synthesis of molecular nitrides remains a challenge and studies of the reactivity and of the nature of the bonding are poorly developed. Here we report the synthesis of the first nitride bridged uranium complexes containing U(vi) and provide a unique comparison of reactivity and bonding in U(vi)/U(vi), U(vi)/U(v) and U(v)/U(v) systems. Oxidation of the U(v)/U(v) bis-nitride [K₂{U(OSi(O^tBu)₃)₃(μ-N)}₂], 1, with mild oxidants yields the U(v)/U(vi) complexes [K{U(OSi(O^tBu)₃)₃(μ-N)}₂], 2 and [K₂{U(OSi(O^tBu)₃)₃}₂(μ-N)₂(μ-I)], 3 while oxidation with a stronger oxidant (“magic blue”) yields the U(vi)/U(vi) complex [{U(OSi(O^tBu)₃)₃}₂(μ-N)₂(μ-thf)], 4. The three complexes show very different stability and reactivity, with N₂ release observed for complex 4. Complex 2 undergoes hydrogenolysis to yield imido bridged [K₂{U(OSi(O^tBu)₃)₃(μ-NH)}₂], 6 and rare amido bridged U(iv)/U(iv) complexes [{U(OSi(O^tBu)₃)₃}₂(μ-NH₂)₂(μ-thf)], 7 while no hydrogenolysis could be observed for 4. Both complexes 2 and 4 react with H⁺ to yield quantitatively NH₄Cl, but only complex 2 reacts with CO and H₂. Differences in reactivity can be related to significant differences in the U–N bonding. Computational studies show a delocalised bond across the U–N–U for 1 and 2, but an asymmetric bonding scheme is found for the U(vi)/U(vi) complex 4 which shows a U–N σ orbital well localised to U N and π orbitals which partially delocalise to form the U–N single bond with the other uranium.

The first examples of molecular compounds containing the cyclic (U(vi)N)₂ and (U(v)U(vi)N)₂ cores were obtained by oxidation of the (U(v)U(v)N)₂ analogue. Different bonding within these complexes yields different stability and reactivity with CO and H₂.     

Selective glucose sensing in complex media using a biomimetic receptor

Glucose is a key biomedical analyte, especially relevant to the management of diabetes. Current methods for glucose determination rely on the enzyme glucose oxidase, requiring specialist instrumentation and suffering from redox-active interferents. In a new approach, a powerful and highly selective achiral glucose receptor is mixed with a sample, l-glucose is added, and the induced CD spectrum is measured. The CD signal results from competition between the enantiomers, and is used to determine the d-glucose content. The involvement of l-glucose doubles the signal range from the CD spectrometer and allows sensitivity to be adjusted over a wide dynamic range. It also negates medium effects, which must be equal for both enantiomers. The method has been demonstrated with human serum, pre-filtered to remove proteins, giving results which closely match the standard biochemical procedures, as well as a cell culture medium and a beer sample containing high (70 mM) and low (0.4 mM) glucose concentrations respectively.

A highly selective receptor, circular dichroism and chiral competition are combined in this versatile method for d-glucose analysis.     

Electrochemical studies of tris(cyclopentadienyl)thorium and uranium complexes in the +2, +3, and +4 oxidation states

Electrochemical measurements on tris(cyclopentadienyl)thorium and uranium compounds in the +2, +3, and +4 oxidation states are reported with C₅H₃(SiMe₃)₂, C₅H₄SiMe₃, and C₅Me₄H ligands. The reduction potentials for both U and Th complexes trend with the electron donating abilities of the cyclopentadienyl ligand. Thorium complexes have more negative An(iii)/An(ii) reduction potentials than the uranium analogs. Electrochemical measurements of isolated Th(ii) complexes indicated that the Th(iii)/Th(ii) couple was surprisingly similar to the Th(iv)/Th(iii) couple in Cp′′-ligated complexes. This suggested that Th(ii) complexes could be prepared from Th(iv) precursors and this was demonstrated synthetically by isolation of directly from UV-visible spectroelectrochemical measurements and reactions of with elemental barium indicated that the thorium system undergoes sequential one electron transformations.

Electrochemical determination of the reduction potentials for a variety of tris(cyclopentadienyl)uranium and thorium complexes, including data on U(ii) and Th(ii) complexes.     

Correction: Direct synthesis of the organic and Ge free Al containing BOG zeolite (ITQ-47) and its application for transformation of biomass derived molecules

Aluminosilicate boggsite (Si/Al-BOG) has been hydrothermally synthesized without adding organic structure-directing agents (OSDAs) in the synthesis gel using the borosilicogermanium ITQ-47 (Si/B-ITQ-47) zeolite as seeds. The introduction of the costly and environmentally less benign phosphazene organic structure-directing agent is not required to grow the zeolite. Physicochemical characterization experiments show that Si/Al-BOG has good crystallinity, high surface area, tetrahedral Al³⁺ species, and acid sites. In order to test the catalytic performance of the zeolite, the synthesis of l,l-lactide from l-lactic acid was performed. Si/Al-BOG exhibits 88.2% conversion of l-lactic acid and 83.8% l,l-lactide selectivity, which are better than those of other zeolites studied up to now.

Aluminosilicate boggsite (Si/Al-BOG) has been hydrothermally synthesized without adding organic structure-directing agents (OSDAs) in the synthesis gel using the borosilicogermanium ITQ-47 (Si/B-ITQ-47) zeolite as seeds.     

Polyphenolic Profile of Callistemon viminalis Aerial Parts: Antioxidant,Anticancer and In Silico 5-LOX Inhibitory Evaluations

Five new compounds viz kaempferol 3-O-(4″-galloyl)-β-d-glucopyranosyl-(1‴→6″)-O-β-d-glucopyranoside (1), kaempferol 3-O-β-d-mannuronopyranoside (2), kaempferol 3-O-β-d-mannopyranoside (3), quercetin 3-O-β-d-mannuronopyranoside (4), 2, 3 (S)- hexahydroxydiphenoyl]-d-glucose (5) along with fifteen known compounds were isolated from 80% aqueous methanol extract (AME) of C. viminalis. AME and compounds exerted similar or better antioxidant activity to ascorbic acid using DPPH, O₂⁻, and NO inhibition methods. In addition, compounds 16, 4, and 7 showed cytotoxic activity against MCF-7 cell lines while 3, 7 and 16 exhibited strong activity against HepG2. An in silico analysis using molecular docking for polyphenolic compounds 2, 3, 7, 16 and 17 against human stable 5-LOX was performed and compared to that of ascorbic acid and quercetin. The binding mode as well as the enzyme-inhibitor interactions were evaluated. All compounds occupied the 5-LOX active site and showed binding affinity greater than ascorbic acid or quercetin. The data herein suggest that AME, a source of polyphenols, could be used against oxidative-stress-related disorders.     

C4-arylation and domino C4-arylation/3,2-carbonyl migration of indoles by tuning Pd catalytic modes: Pd(i)–Pd(ii) catalysis vs. Pd(ii) catalysis

Efficient C4-arylation and domino C4-arylation/3,2-carbonyl migration of indoles have been developed. The former route enables C4-arylation in a highly efficient and mild manner and the latter route provides an alternative straightforward protocol for synthesis of C2/C4 disubstituted indoles. The mechanism studies imply that the different reaction pathways were tuned by the distinct acid additives, which led to either the Pd(i)–Pd(ii) pathway or Pd(ii) catalysis.

C4-arylation via Pd(i)–Pd(ii) catalysis and domino C4-arylation/3,2-carbonyl migration of indoles via Pd(ii) catalysis tuning by acids have been developed.