Oxygen mediated oxidative couplings of flavones in alkaline water.

Catalyzed oxidative C-C bond coupling reactions play an important role in the chemical synthesis of complex natural products of medicinal importance. However, the poor functional group tolerance renders them unfit for the synthesis of naturally occurring polyphenolic flavones. We find that molecular oxygen in alkaline water acts as a hydrogen atom acceptor and oxidant in catalyst-free (without added catalyst) oxidative coupling of luteolin and other flavones.

Metabolic characterisation of eight Escherichia coli strains including "Big Six" and acidic responses of selected strains revealed by NMR spectroscopy.

The metabolic diversity of Escherichia coli strains (non-pathogenic E. coli ATCC 25922, and pathogenic E. coli O157:H7, O26:H11, O45:H2, O103:H11, O111, O121:H19, and O145) was tested using nuclear magnetic resonance.

Metabolic analysis of salicylic acid-induced chilling tolerance of banana using NMR.

Banana is highly susceptible to low temperature and salicylic acid (SA) can effectively improve the chilling tolerance. The metabolic changes of SA induced chilling responses of banana were studied. Bananas normally ripened under 15 °C and dramatic metabolic difference compared with other groups was recorded.

Elucidating antimicrobial mechanism of nisin and grape seed extract against Listeria monocytogenes in broth and on shrimp through NMR-based metabolomics approach.

Nisin and grape seed extract (GSE) have been widely used as food preservatives; however, the mechanism against pathogens at molecular level has not been well elucidated. This work aimed to investigate their antimicrobial effect against Listeria monocytogenes and to elucidate the mechanism by NMR-based metabolomics. Nisin exhibited enhanced in vitro antilisterial effect when combined with GSE (4.

Comparison of metabolic response between the planktonic and air-dried Escherichia coli to electrolysed water combined with ultrasound by H NMR spectroscopy.

The antimicrobial effects of electrolysed water and ultrasound have been well reported; however, little attention was paid to their effects on the metabolite changes of bacteria in different states. In this study, the metabolomic variations of Escherichia coli ATCC 25922 in planktonic and adherent state (air-dried on stainless steel coupons) after the combination treatment of low-concentration acidic electrolysed water (AEW, free available chlorine (FAC): 4 mg/L) and ultrasound were characterised, by conducting multivariate data analysis based on nuclear magnetic resonance (NMR) spectroscopy. Overall, 43 metabolites were identified in two states of E.

Cyclohexyl-Fused, Spirobiindane-Derived, Phosphine-Catalyzed Synthesis of Tricyclic γ-Lactams and Kinetic Resolution of γ-Substituted Allenoates.

A C-symmetric chiral phosphine catalyst, NUSIOC-Phos, which can be easily derived from cyclohexyl-fused spirobiindane, was introduced. A highly enantioselective domino process involving pyrrolidine-2,3-diones and γ-substituted allenoates catalyzed by NUSIOC-Phos has been disclosed. Diastereospecific tricyclic γ-lactams containing five contiguous stereogenic centers were obtained in high yields and with nearly perfect enantioselectivities.

Effect of vacuum impregnated fish gelatin and grape seed extract on metabolite profiles of tilapia (Oreochromis niloticus) fillets during storage.

Traditional methods evaluating fish quality do not involve comprehensive qualification and quantification of quality-related components. The objective of this study was to investigate the effect of vacuum impregnated fish gelatin (FG) and grape seed extract (GSE) on metabolites of tilapia fillets during storage using nuclear magnetic resonance (NMR). Totally 42 metabolites were identified, 36 of which were quantified.

Metabolomic analysis of energy regulated germination and sprouting of organic mung bean (Vigna radiata) using NMR spectroscopy.

Germination and sprouting are regulated by the energy status. In the present study, mung bean seeds were treated with adenosine triphosphate and 2,4-dinitrophenol (DNP). The metabolomic changes during development of mung beans under different energy statuses were investigated.

Graphene-Oxide-Catalyzed Direct CH-CH-Type Cross-Coupling: The Intrinsic Catalytic Activities of Zigzag Edges.

The development of graphene oxide (GO)-based materials for C-C cross-coupling represents a significant advance in carbocatalysis. Although GO has been used widely in various catalytic reactions, the scope of reactions reported is quite narrow, and the relationships between the type of functional groups present and the specific activity of the GO are not well understood. Herein, we explore CH-CH-type cross-coupling of xanthenes with arenes using GO as real carbocatalysts, and not as stoichiometric reactants.

Metabolite profiling of Listeria innocua for unravelling the inactivation mechanism of electrolysed water by nuclear magnetic resonance spectroscopy.

Bactericidal effects of low concentration electrolysed water (LcEW) on microorganisms are previously well reported; however, the inactivation mechanism of EW is not understood. The lethal and sublethal injuries of L. monocytogenes and L.

Identification of Cyclic Dipeptides from Escherichia coli as New Antimicrobial Agents against Ralstonia Solanacearum.

is a causative agent of bacterial wilt in many important crops throughout the world. How to control bacterial wilt caused by is a major problem in agriculture. In this study, we aim to isolate the biocontrol agents that have high efficacy in the control of bacterial wilt.

Divergent reactivities in fluoronation of allylic alcohols: synthesis of -fluoroalkenes carbon-carbon bond cleavage.

An unconventional cleavage of an unstrained carbon-carbon bond in allylic alcohols can be induced by the use of -fluorobenzenesulfonimide (NFSI) under catalyst-free conditions. By using this simple procedure, a wide range of functionalized -fluoroalkenes can be accessed in high yield and selectivity from cyclic and acyclic allylic alcohols.

Three-component reactions of isocyanoacetates, amines and 3-formylchromones initiated by an unexpected aza-Michael addition.

We present herein a new mode of three-component reactions between isocyanoacetates, amines and 3-formylchromones. Both experimental and DFT studies revealed that this Ag-catalyzed unusual transformation is initiated by a facile aza-Michael addition instead of the conventional imine condensation. This catalytic method enables an efficient synthesis of polysubstituted pyrroles.

Fused Bicyclic Caspase-1 Inhibitors Assembled by Copper-Free Strain-Promoted Alkyne-Azide Cycloaddition (SPAAC).

Challenges exist in the development of potent and selective small-molecule inhibitors against caspase-1. Herein, by making use of the copper-free strain-promoted alkyne-azide cycloaddition (SPAAC) reaction between difluorinated cyclooctynes (DIFOs) and various azide-containing compounds, we showed for the first time that potential caspase-1 inhibitors could be rapidly synthesized. The resulting fused bicyclic compounds structurally resembled the central portion (P -P ) of Pralnacasan (a well-known small molecule caspase-1 inhibitor), with diversity at the P -position of the parental inhibitor conveniently installed from the azide component.

Enantioselective desymmetrization of cyclohexadienones via an intramolecular Rauhut-Currier reaction of allenoates.

The Rauhut-Currier (RC) reaction represents an efficient method for the construction of carbon-carbon bond in organic synthesis. However, the RC reactions involving allenoate substrates are very rare, and in particular, asymmetric intramolecular RC reaction of allenoates is yet to be discovered. Here, we show that the intramolecular RC reaction proceeds smoothly in the presence of 1 mol% β-ICD, and bicyclic lactones are obtained in high yields and with excellent enantiomeric excesses.

Synthesis of Disubstituted 3-Phenylimidazo[1,2-a]pyridines via a 2-Aminopyridine/CBrCl α-Bromination Shuttle.

A versatile protocol for the synthesis of disubstituted 3-phenylimidazo[1,2-a]pyridines by coupling 2-aminopyridine with phenylacetophenones, phenylacetones, or β-tetralone has been developed. Isolated yields of up to 97% were obtained at 80 °C within 5 h. The 2-aminopyridine/CBrCl system acts as an α-bromination shuttle by transferring Br from CBrCl to the α-carbon of the carbonyl moiety.

Highly emissive, solution-processable and dynamic Eu(III)-containing coordination polymers.

A new class of soluble Eu(III) coordination polymers based on a tridentate ditopic pybox ligand has been developed displaying high metal emission quantum yields of up to 73% as well as a unique dynamic behaviour in solution.

The host plant metabolite glucose is the precursor of diffusible signal factor (DSF) family signals in Xanthomonas campestris.

Plant pathogen Xanthomonas campestris pv. campestris produces cis-11-methyl-2-dodecenoic acid (diffusible signal factor [DSF]) as a cell-cell communication signal to regulate biofilm dispersal and virulence factor production. Previous studies have demonstrated that DSF biosynthesis is dependent on the presence of RpfF, an enoyl-coenzyme A (CoA) hydratase, but the DSF synthetic mechanism and the influence of the host plant on DSF biosynthesis are still not clear.

Biosynthesis of mupirocin by Pseudomonas fluorescens NCIMB 10586 involves parallel pathways.

Mupirocin, a clinically important antibiotic produced via a trans-AT Type I polyketide synthase (PKS) in Pseudomonas fluorescens, consists of a mixture of mainly pseudomonic acids A, B, and C. Detailed metabolic profiling of mutant strains produced by systematic inactivation of PKS and tailoring genes, along with re-feeding of isolated metabolites to mutant stains, has allowed the isolation of a large number of novel metabolites, identification of the 10,11-epoxidase, and full characterization of the mupirocin biosynthetic pathway, which proceeds via major (10,11-epoxide) and minor (10,11-alkene) parallel pathways.

New stilbenoids isolated from fungus-challenged black skin peanut seeds and their adipogenesis inhibitory activity in 3T3-L1 cells.

One new stilbene derivative (3,5,3'-trihydroxy-4'-methoxy-5'-isopentenylstilbene, MIP) and two new stilbene dimers (arahypin-11 and arahypin-12) together with three known stilbenoids (arachidin-1, arachidin-3, and SB-1) were isolated from black skin peanut seeds challenged by the fungal strain Rhizopus oligoporus . The structures of the three new compounds were elucidated by analysis of HRESIMS, UV, 1D and 2D NMR spectra. The antiadipogenic and cytotoxic effects of the isolated compounds were investigated using 3T3-L1 cells at a concentration range of 1-10 μM.

The diffusible factor synthase XanB2 is a bifunctional chorismatase that links the shikimate pathway to ubiquinone and xanthomonadins biosynthetic pathways.

The diffusible factor synthase XanB2, originally identified in Xanthomonas campestris pv. campestris (Xcc), is highly conserved across a wide range of bacterial species, but its substrate and catalytic mechanism have not yet been investigated. Here, we show that XanB2 is a unique bifunctional chorismatase that hydrolyses chorismate, the end-product of the shikimate pathway, to produce 3-hydroxybenzoic acid (3-HBA) and 4-HBA.

Patterned recognition of amines and ammonium ions by a pyridine-based helical oligoamide host.

In response to binding to amine and ammonium guests of varying types, a pyridine-based folding oligomer displays fingerprint regions in its (1)H NMR spectra that allow for the easy identification and classification of the bound guests.

Copper-mediated C-H activation/C-S cross-coupling of heterocycles with thiols.

We report the synthesis of a series of aryl- or alkyl-substituted 2-mercaptobenzothiazoles by direct thiolation of benzothiazoles with aryl or alkyl thiols via copper-mediated aerobic C-H bond activation in the presence of stoichiometric CuI, 2,2'-bipyridine and Na(2)CO(3). We also show that the approach can be extended to thiazole, benzimidazole, and indole substrates. In addition, we present detailed mechanistic investigations on the Cu(I)-mediated direct thiolation reactions.

Xanthomonas campestris diffusible factor is 3-hydroxybenzoic acid and is associated with xanthomonadin biosynthesis, cell viability, antioxidant activity, and systemic invasion.

Xanthomonas campestris pv. campestris produces a membrane-bound yellow pigment called xanthomonadin. A diffusible factor (DF) has been reported to regulate xanthomonadin biosynthesis.

Manipulation of quorum sensing regulation in Pseudomonas fluorescens NCIMB 10586 to increase mupirocin production.

Transcription of the 74 kb Pseudomonas fluorescens mupirocin [pseudomonic acid (PA)] biosynthesis cluster depends on quorum sensing-dependent regulation via the LuxI/LuxR homologues MupI/MupR. To facilitate analysis of novel PAs from pathway mutants, we investigated factors that affect mup gene expression. First, the signal produced by MupI was identified as N-(3-oxodecanoyl)homoserine lactone, but exogenous addition of this molecule did not activate mupirocin production prematurely nor did expression of mupI in trans increase metabolite production.