Phenolic Ring Research Articles

Self-assembled supramolecular structures of O,N,N' tridentate imidazole-phenol Schiff base compounds.

Three imidazole-derived Schiff base compounds comprising an N-methyl imidazole group coupled to a phenol ring through an imine bond were synthesised. The structures differ by the substituent on the phenol ring at the 4-position: methyl (1), tert-butyl (2) and hydrogen (3). The compounds were synthesised using both a traditional reflux in solvent as well as an environmentally friendly solid-state reaction. Compounds (1)–(3) as well as the hemihydrate of (3) were all studied by single crystal X-ray diffraction. The asymmetric unit of compound (1) consists of two nominally planar molecules linked by hydrogen bonds to form a dimeric supramolecular structure. This dimeric structure was ubiquitous for the anhydrous forms of (1)–(3). The complementary hydrogen bonding motif between the imidazole N atoms and the phenol OH results in a stable 16-membered hydrogen-bonded ring. The asymmetric unit of (3) comprises two symmetry-independent molecules one of which has co-planar imidazole and phenol rings while the other shows a significantly oblique orientation. The hemihydrate of (3) similarly forms extensive hydrogen bonds, though in the form of a water-bridged dimeric structure. The hydrogen bond lengths (D⋯A) for compounds (1)–(3) are relatively short, ranging from 2.662(1) to 2.688(1) Å. DFT was used to understand the relative stability of the monomeric and dimeric species. These showed the hydrogen-bonded supramolecular structures were ca. 101 kJ mol−1 lower in energy than the non-interacting monomers. Scan simulations were used to calculate the total energy of the molecule as a function of phenyl ring rotation and showed why the expected planar configuration for a conjugated π-system was not observed experimentally. The barrier to rotation was found to be relatively low, 7.97(6) kJ mol−1, with the lowest energy conformations subtending dihedral angles of 22.319, 24.265 and 25.319° for molecules (1), (2) and (3), respectively. The electrostatic potential maps are able to succinctly explain the stability of the hydrogen bonds through the partial charges of the interacting atoms. TD-DFT simulations and analysis of the simulated and experimental UV/visible spectra suggest that the dimeric supramolecular structure is a stable species in solution. This was confirmed through 1H NMR titrations and an equilibrium constant of 0.16(5) M−1 was estimated.

Control of DNA structure and function by phytochemicals/DNA interaction: Resveratrol/piceatannol induces Cu2+-independent, cleavage of supercoiled plasmid DNA

Topoisomerases are enzymes that catalyze DNA unwinding and scissions to resolve topological entanglements possibly arising during DNA replication/transcription. Chemicals which disrupt or inhibit topoisomerase-mediated DNA unwinding can induce breaks that subsequently lead to programmed cell death. Herein we perform experiments guided by the following considerations. First, topoisomerase 1 initiates DNA cleavage utilizing the hydroxyl group of tyrosine 723 on its catalytic site as a nucleophile to attack the electrophilic phosphate on the DNA sugar-phosphate backbone. Secondly, the grape polyphenol resveratrol displays both topoisomerase inhibitory and Cu2+-dependent DNA-cutting activities, which contribute to its DNA replication/transcription inhibitory/anti-tumorigenic effects. Lastly, resveratrol contains a tyrosine-like phenolic ring; thus, upon binding to DNA whether resveratrol could act as a tyrosine mimetic to unwind and cut DNA via its hydroxyl groups warrants investigation. Polyphenol-DNA interactions (PDIs) were investigated using UV–visible spectral analysis; additionally, PDI mediated DNA changes were further analyzed by agarose gel electrophoresis using 3 supercoiled plasmid DNAs (pBR322, pSJ3, pHOT-1) as substrates. Resveratrol mediates time- and temperature-dependent, Cu2+-independent, non-enzymatic cleavage of supercoiled plasmid DNA into open, circular DNA products. Varying degree of unwinding of supercoiled DNA nucleolytic activity was also observed with other polyphenols including, piceatannol, quercetin, myricetin and EGCG. Interestingly, we found that piceatannol mediated Cu2+-independent DNA-cleavage activity was abolished by EDTA. The PDI-mediated nucleolytic cleavage of supercoiled DNA reported herein shows that polyphenolic phytochemicals display genome-active, nuclear effects by directly targeting the DNA topology which in turn could impact macromolecular processes associated with faithful replication and transmission of genetic information.

Sequential Detection of Palladium and Chromium Oxyanion by a Fluorescein Based Chemosensor in Mixed Aqueous Media

A new highly selective chemosensor, based on fluorescein-allyloxy benzene conjugate 1, was developed for the sequential detection of palladium and chromium oxyanions in a mixed aqueous media, and was studied by UV-visible and fluorescence spectroscopy. The sensing of palladium ions produces a chemodosimetric and ratiometric change in the emission band of 1 from 450 to 525 nm, followed by the sensing of chromate ions by 2 that quenches the emission band at 525 nm in a buffered H2O: DMF solution (9:1, pH = 7.4). The rate constants of palladium and chromate ions were found to be 8.6 × 105 M−1, 2.1 × 105 M−1, and 5.4 × 104 M−1 respectively. The chemosensor 1 has a palladium detection limit of 49 ppb while the sequential detection limit of chromate ions (CrO42− and Cr2O72−) were 127 and 259 ppb. The ratiometric change in the emission is produced due to the deallylation of 1 by palladium to produce 2 that restores the ESIPT (excited state intramolecular proton transfer) of the phenolic ring and enhances the electron transfer (ET) phenomenon from the phenolic group to fluorescein. The sequential binding of chromate ions to 2 inhibits the ESIPT and causes chelation enhanced quenching (CHEQ) of the fluorescence.

Topical Application of 7,3',4'-Trihydroxyisoflavone Alleviates Atopic Dermatitis-Like Symptoms in NC/Nga Mice.

Atopic dermatitis is a skin disease characterized by chronic inflammatory lesions, and new therapies are needed to address its rising prevalence. Soy isoflavone has been highlighted as a potential new cosmeceutical material that may have applications in atopic dermatitis care. We have developed a technique to attach an additional -OH group to the ortho position of -OH in the phenol ring using a special enzyme. By adding the -OH group to daidzein, 7,3',4'-trihydroxyisoflavone can be generated for possible use as a cosmeceutical and functional food material. In this study, we sought to examine the anti-atopic effects of 7,3',4'-trihydroxyisoflavone, an analog of daidzein. Topical application of 7,3',4'-trihydroxyisoflavone reduced Dermatophagoides farina extract-induced atopic dermatitis symptoms in NC/Nga mice. Histological analysis demonstrated that 7,3',4'-trihydroxyisoflavone suppressed D. farina extract-induced infiltration of eosinophils and mast cells into skin lesions. We also found that 7,3',4'-trihydroxyisoflavone significantly reduces the D. farina extract-induced increases in serum IgE and macrophage-derived chemokine (CCL22) levels. We observed that 7,3',4'-trihydroxyisoflavone suppresses atopic markers including macrophage-derived chemokine (CCL22) and thymus and activation-regulated chemokine (CCL17) in HaCaT cells. 7,3',4'-Trihydroxyisoflavone also reduced TNF-α/IFN-γ-induced phosphorylation of ERK1/2 and JNK1/2. These results highlight several desirable properties of 7,3',4'-trihydroxyisoflavone, which support its use as a cosmeceutical ingredient for the treatment of atopic dermatitis.

Degradation and transformation of bisphenol A in UV/Sodium percarbonate: Dual role of carbonate radical anion

The bicarbonate and carbonate ions (HCO3− &CO32−) will consume hydroxyl radical (HO•) to generate carbonate radical anion (CO3•−) in hydroxyl radical based advanced oxidation processes (HO•−AOPs) resulting in reduced oxidation efficiencies of the systems. However, despite the HO• quenching effect of carbonate species, the contribution of CO3•− to the degradation of bisphenol A (BPA) was observed in UV/sodium percarbonate (UV/SPC). In order to study the performance of UV/SPC for BPA degradation and the role of CO3•− in this process, the degradation kinetics and mechanisms of BPA in UV/SPC and in UV/hydrogen peroxide (UV/H2O2) were compared at equivalent concentration of H2O2. In this study, the observed degradation rates of BPA by UV/SPC and by UV/H2O2 in Milli-Q water were similar. Variation of the BPA degradation rates in the presence of radical quenchers, tert-butanol and phenol, suggested that both CO3•− and HO• contributed to the degradation of BPA in UV/SPC. Second order rate constant of CO3•− towards BPA (kCO3•−+BPA = 2.23 × 108 M−1 s−1) and steady state concentrations of CO3•− ([CO3•−]ss = 2.3 × 10−12 M) and HO• ([HO•]ss = 1.82 × 10−14 M) in UV/SPC were determined with competition kinetics at 1 mM SPC and pH 8.5. The high [CO3•−]ss observed in UV/SPC compensated for the smaller kCO3•−+BPA compared to kHO•+BPA and the consumption of HO• making the degradation rate of BPA in UV/SPC comparable to that in UV/H2O2. Detailed studies on identification of transformation products (TPs) of BPA in UV/SPC revealed that phenol ring and isopropylidene bridge were the main reactive sites of BPA. Degradation pathways were proposed accordingly. The results of kinetic and mechanistic studies provide better fundamental understanding of the degradation of BPA in UV/SPC and HCO3−&CO32− impact on BPA degradation by HO•−AOPs. This also demonstrates potential for CO3•− based water purification technologies.

Metabolism of 17β-estradiol by Novosphingobium sp. ES2-1 as probed via HRMS combined with 13C3-labeling

This study investigated the biodegradation and metabolic mechanisms of 17β-estradiol (E2) by Novosphingobium sp. ES2-1 isolated from the activated sludge in a domestic sewage treatment plant (STP). It could degrade 97.1% E2 (73.5 μmol/L) in 7 d with a biodegradation half-life of 1.29 d. E2 was initially converted to estrone (E1), then to 4-hydroxyestrone (4-OH-E1), before subsequent monooxygenation reactions cleaved 4-OH-E1 into a metabolite with long-chain ketones structure (metabolite P8). However, when 4-OH-E1 was cleaved through the 4,5-seco pathway, the resulting phenol ring cleavage product could randomly condense with NH3 to yield a pyridine derivative, accompanied by the uncertain loss of a carboxy group at C4 before the condensation. The derivative was further oxidized into the metabolites with both pyridine and long-chain ketones structure (metabolite N5) through a similar formation mechanism as for P8 performed. This research presents several novel metabolites and shows that E2 can be biodegraded into the metabolite with long-chain structure through three optional pathways, thereby reducing E2 contamination.

Phenolic Compound Biotransformation by Trametes versicolor ATCC 200801 and Molecular Docking Studies.

The filamentous fungus Trametes versicolor is a rich source of laccase (Tvlac). Laccases catalyze reactions that convert substituted phenol substrates into diverse derivatives through aromatic oxidation. We investigated methyl p-coumarate, methyl ferulate, and methyl caffeate biotransformation by Trametes versicolor ATCC 200801. Despite substrate similarity, the biotransformation reactions varied widely. Only methyl p-coumarate was converted into three derivatives. We isolated and identified the chemical structures of such derivatives by NMR and IR analysis. Hydroxylation, methylation, and hydrolysis were the main reactions resulting from the studied biotransformation. We also analyzed the interactions between Tvlac (PDB ID: 1GYC) and the three phenolic substrates by molecular docking simulations. The substituents in the phenol ring influenced substrate conformation and orientation in the Tvlac site. The biotransformation reaction selectivity correlated with the different binding energies to the Tvlac site. Our results demonstrated that docking studies successfully predict the biotransformation of cinnamic acid analogs by T. versicolor.

Multivariate characterisation of Italian monovarietal red wines using MIR spectroscopy

Aim: The aim of this study was to investigate the application of mid-infrared (MIR) spectroscopy combined with multivariate analysis, to provide a rapid screening tool for discriminating among different Italian monovarietal red wines based on the relationship between grape variety and wine composition in particular phenolic compounds.Methods and results: The MIR spectra (from 4000 to 700 cm‒1) of 110 monovarietal Italian red wines, vintage 2016, were collected and evaluated by selected multivariate data analyses, including principal component analysis (PCA), linear discriminant analysis (DA), support vector machine (SVM), and soft intelligent modelling of class analogy (SIMCA). Samples were collected directly from companies across different regions of Italy and included 11 grape varieties: Sangiovese, Nebbiolo, Aglianico, Nerello Mascalese, Primitivo, Raboso, Cannonau, Teroldego, Sagrantino, Montepulciano and Corvina.
 PCA showed five wavelengths that mainly contributed to the PC1, including a much-closed peak at 1043 cm‒1, which correspond to the C–O stretch absorption bands that are important regions for glycerol, whereas the ethanol peaks at around 1085 cm‒1. The band at 877 cm‒1 are related to the C–C stretching vibration of organic molecules, whereas the asymmetric stretching for C–O in the aromatic –OH group of polyphenols is within spectral regions from 1050 to 1165 cm‒1. In particular, the (1175)–1100–1060 cm‒1 vibrational bands are combination bands, involving C–O stretching and O–H deformation of phenolic rings. The 1166–1168 cm‒1 peak is attributable to in-plane bending deformations of C–H and C–O groups of polyphenols, respectively, for which polymerisation may cause a slight peak shift due to the formation of H-bridges.The best result was obtained with the SVM, which achieved an overall correct classification for up to 72.2% of the training set, and 44.4% for the validation set of wines, respectively. The Sangiovese wines (n=19) were split into two sub-groups (Sang-Romagna, n=12 and Sang-Tuscany, n=7) considering the indeterminacy of its origins, which is disputed between Romagna and Tuscany. Although the classification of three grape varieties was problematic (Nerello Mascalese, Raboso and Primitivo), the remaining wines were almost correctly assigned to their actual classes.Conclusions: MIR spectroscopy coupled with chemometrics represents an interesting approach for the classification of monovarietal Italian red wines, which is important in quality control and authenticity monitoring.Significance and impact of the study: Authenticity is a main issue in winemaking in terms of quality evaluation and adulteration, in particular for origin certified/protected wines, for which the added marketing value is related to the link of grape variety with the area of origin. This study is part of the D-wine project “The diversity of tannins in Italian red wines”.

Enhancing thermal properties of polybenzoxazine by incorporation of 4-cyanophenol

In order to study the effect of strong electron-withdrawing group on thermal properties of polybenzoxazine, 4-cyanophenol-based benzoxazines were prepared and their cured samples were investigated by FTIR, TGA, TGA-FTIR, Py-GC–MS and LOI tests. FTIR results indicate that nitrile group hardly polymerized and existed in polybenzoxazine at present cured conditions. TGA results show that the introduction of nitrile group in phenol could remarkably improve the char yield at 800 °C, thermal and thermo-oxidative stability of polybenzoxazine compared with the analogous polybenzoxazines without electron-withdrawing group. Moreover, nitrile group decreased the charge density of phenolic ring and made hydroxyl be cleared more easily, the free hydroxyl not only could oxidize −CH2- of −CH2-NR−CH2- in polybenzoxaizne into CO2 but also transformed into H2O, resulting in that there was always a volatilization of CO2 and H2O during thermal degradation process. Furthermore, the incorporation of nitrile group also increased significantly the flame retardancy of polybenzoxazine.

The Fluid Aspect of the Mediterranean Diet in the Prevention and Management of Cardiovascular Disease and Diabetes: The Role of Polyphenol Content in Moderate Consumption of Wine and Olive Oil.

A growing interest has emerged in the beneficial effects of plant-based diets for the prevention of cardiovascular disease, diabetes and obesity. The Mediterranean diet, one of the most widely evaluated dietary patterns in scientific literature, includes in its nutrients two fluid foods: olive oil, as the main source of fats, and a low-to-moderate consumption of wine, mainly red, particularly during meals. Current mechanisms underlying the beneficial effects of the Mediterranean diet include a reduction in inflammatory and oxidative stress markers, improvement in lipid profile, insulin sensitivity and endothelial function, as well as antithrombotic properties. Most of these effects are attributable to bioactive ingredients including polyphenols, mono- and poly-unsaturated fatty acids. Polyphenols are a heterogeneous group of phytochemicals containing phenol rings. The principal classes of red wine polyphenols include flavonols (quercetin and myricetin), flavanols (catechin and epicatechin), anthocyanin and stilbenes (resveratrol). Olive oil has at least 30 phenolic compounds. Among them, the main are simple phenols (tyrosol and hydroxytyrosol), secoroids and lignans. The present narrative review focuses on phenols, part of red wine and virgin olive oil, discussing the evidence of their effects on lipids, blood pressure, atheromatous plaque and glucose metabolism.

Structural, spectroscopic and first-principles studies of new aminocoumarin derivatives.

The new aminocoumarin derivatives 3-[1-(3-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (1), 3-[1-(4-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (2), and 3-[1-(2-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (3), all C17H13NO4, were synthesized by reacting an equimolar amount of 3-acetyl-4-hydroxycoumarin and the corresponding aminophenol in absolute ethanol. Structural and spectroscopic analysis of these phases revealed that derivatives (1) and (2) are isomers of previously reported (3) [Brahmia et al. (2013). Acta Cryst. E69, o1296]. The crystal structures of meta derivative (1) and para derivative (2) were ab initio determined from powder X-ray diffraction data using the direct-space approach. Both (1) and (2) adopt the orthorhombic space group P212121. These isomers show hydrogen bonds and rich π-π stacking, together with π...H interactions, which are built by conjugated systems of coumarin and phenol rings. In the crystalline lattice, the packing of (1) and (3) are mainly stabilized through O-H...O hydrogen bonding between neighbouring coumarin molecules, while hydrogen bonds between coumarin and water molecules build the stable crystal structure of derivative (2). A big similarity in the skeletons of the IR spectra of these isomers was noticed. Derivative (2) exhibits two weak bands which were not present in the spectra of the other two derivatives, at 2370 and 2948 cm-1, which can be assigned to the O-H vibrations of the solvent (H2O) trapped in the structure of (2). These aminocoumarin derivatives display absorption maxima in the visible region, attributed to π-π delocalization involving the whole electronic system of the compounds with a considerable charge-transfer character originating from the aminophenyl ring and pointing towards the coumarin system which is characterized by a high electron-accepting character. Additionally, the isolated molecular ground-state geometries were optimized at the PBE0/TZP level and the electronic properties, molecular electrostatic potential and Hirshfeld charges were determined.

Nitric Oxide Dioxygenase Activity of a Nitrosyl Complex of Mn(II)-Porphyrinate in the Presence of Superoxide: Formation of a Mn(IV)-oxo Species through a Putative Peroxynitrite Intermediate.

A nitrosyl complex of MnII-porphyrinate, [(F20TPP)MnII(NO)], 1 (F20TPPH2 = 5,10,15,20 tetrakis(pentafluorophenyl)porphyrin), was synthesized and characterized. Spectroscopic and structural characterization revealed complex 1 as a penta-coordinated MnII-nitrosyl with a linear Mn-N-O (180.0°) moiety. Complex 1 does not react with O2. However, it reacts with superoxide (O2-) in THF at -80 °C to result in the corresponding nitrate (NO3-) complex, 2, via the formation of a presumed MnIII-peroxynitrite intermediate. ESI-mass spectrometry and UV-visible and X-band EPR spectroscopic studies suggest the generation of MnIV-oxo species in the reaction through homolytic cleavage of the O-O bond of the peroxynitrite ligand as proposed in NOD activity. The intermediate formation of the MnIII-peroxynitrite was further supported by the well accepted phenol ring nitration which resembles the biologically well-established tyrosine nitration.

Relevance of the antioxidant properties of methotrexate and doxycycline to their treatment of cardiovascular disease.

Many medications exhibit clinical benefits that are unrelated to their primary therapeutic uses. In many cases, the mechanisms underpinning these pleotropic effects are unknown. Two commonly prescribed medications that exhibit pleotropic benefits in cardiovascular disease and other diseases associated with chronic inflammation are methotrexate (MTX) and doxycycline (DOX). The vast majority of cardiovascular disease is associated with atherosclerosis. Because atherosclerosis is a chronic inflammatory disease, possible mechanisms by which MTX and DOX reduce inflammation have been investigated. Interestingly, the primary structure of both of these medications contain aromatic phenolic rings, which resemble polyphenols that are known to possess antioxidant activity. Inflammation and oxidative stress are intimately related. Inflammation promotes oxidative stress, which in turn leads to further inflammation; in this way, oxidative stress and inflammation can establish a self-perpetuating cycle. It has been shown that MTX and DOX act as antioxidants and are capable of scavenging free radicals and the reactive oxygen species (ROS) superoxide (O2-). Furthermore, both MTX and DOX inhibit the formation of malondialdehyde acetaldehyde (MAA) adducts, products of oxidative stress and lipid peroxidation. Importantly, MAA-adducts are highly immunogenic and initiate inflammatory responses; thereby, fueling the cycle of inflammation and oxidative stress that results in chronic inflammation. Thus, reducing the formation of MAA-adducts may ameliorate inflammation that leads to ROS production and in this way, break the self-sustaining cycle of oxidative stress and inflammation. It is possible that the under-recognized antioxidant properties of these medications may be a mechanism by which they and other medications provide pleotropic benefit in the treatment of chronic inflammatory disease.

Design, synthesis and preliminary in-vitro studies of novel boronated monocarbonyl analogues of Curcumin (BMAC) for antitumor and β-amiloyd disaggregation activity

Curcumin is currently being investigated for its capacity to treat many types of cancer and to prevent the neuron damage that is observed in Alzheimer’s disease (AD). However, its clinical use is limited by its low stability and solubility in aqueous solutions. In this study, we propose a completely new class of boronated monocarbonyl analogues of Curcumin (BMAC, 6a-c), in which a carbonyl group replaces the Curcumin β-diketone functionality, and an ortho-carborane, an icosahedral boron cluster, substitutes one of the two phenolic rings. BMAC antitumor activity against MCF7 and OVCAR-3 cell lines was assessed in vitro and compared to that of Curcumin and the corresponding MAC derivative. BMAC 6a-c showed efficiencies that are comparable to that of MAC and superior to that of Curcumin in both the cell lines. Moreover, the inhibition of the formation of β-amyloid aggregates by BMAC 6a-c was evaluated and it was shown that compound 6c, which contains two OH moieties, has a better efficiency than Curcumin. The presence of a second –OH group can enhance the compound’s binding efficacy with β-amyloid aggregates. For the future, the presence of at least one carborane group means that the BMAC antitumor effect can be coupled with Boron Neutron Capture Therapy.

Accelerated biodegradation of p-tert-butylphenol in the Phragmites australis rhizosphere by phenolic root exudates

Phenolic root exudates (PREs) released from plants are potentially effective for the degradation of aromatic compounds, yet the inherent process and mechanism remain insufficiently elucidated. In this study, we selected four representative PREs of P. australis, namely p-hydroxybenzoic acid (PHA), p-coumaric acid (PCA), caffeic acid (CA), and ferulic acid (FA), to investigate the accelerated biodegradation of p-tert-butylphenol (PTBP) by PREs in the rhizosphere and their mechanisms. The results showed that PTBP was initially adsorbed to root surface, and subsequently degraded by rhizosphere microbes of P. australis. The presence of PHA, PCA, and FA was beneficial for the enrichment of PTBP-degrading bacteria and the decomposition of PTBP, particularly PCA. Although CA was also favorable to microbial accumulation, it had no effect on PTBP degradation. This is possibly because PHA, PCA, and FA with monohydroxy structure similar like PTBP may promote the microbes for releasing hydroxylase to catalyze the phenolic ring hydroxylation followed by a cleavage pathway, whereas CA with ortho-dihydroxy structure cannot act on this reaction. Collectively, our data suggest PREs can accelerate biodegradation of specific aromatic compounds (e.g. PTBP) via co-metabolism in the rhizosphere of plants, according to their functional structures.

(E)-1-(2-Hydroxy-6-methoxyphenyl)-3-(2-methoxynaphthalen-1-yl)prop-2-en-1-one

In the title compound, C21H18O4, the dihedral angle between the naphthelene ring system (r.m.s. deviation = 0.014 Å) and the benzene ring is 9.68 (1)°. The C atom of the methoxy group of the naphthalene ring system is almost coplanar with the ring [C—O—C—C = −2.0 (3)°], whereas the C atom of the methoxy group of the phenol ring is slightly twisted [C—O—C—C = 6.2 (3)°]. An intramolecular O—H...O hydrogen bond generates an S(6) ring motif.

Structural Evidence of Photoisomerization Pathways in Fluorescent Proteins.

Double-bond photoisomerization in molecules such as the green fluorescent protein (GFP) chromophore can occur either via a volume-demanding one-bond-flip pathway or via a volume-conserving hula-twist pathway. Understanding the factors that determine the pathway of photoisomerization would inform the rational design of photoswitchable GFPs as improved tools for super-resolution microscopy. In this communication, we reveal the photoisomerization pathway of a photoswitchable GFP, rsEGFP2, by solving crystal structures of cis and trans rsEGFP2 containing a monochlorinated chromophore. The position of the chlorine substituent in the trans state breaks the symmetry of the phenolate ring of the chromophore and allows us to distinguish the two pathways. Surprisingly, we find that the pathway depends on the arrangement of protein monomers within the crystal lattice: in a looser packing, the one-bond-flip occurs, whereas, in a tighter packing (7% smaller unit cell size), the hula-twist occurs.

CRYSTAL STRUCTURE OF (E)-N′-((1H-PYRROL-2-YL)METHYLENE)-4-HYDROXYBENZOHYDRAZIDE

The title compound corresponds to an enaminone E isomer in the solid state. X-ray structure shows that this crystallizes in the orthorrombic system, with space group Pna21 with 2 independent molecules in the asymmetric unit in a non-centrosymmetric setting. The CNNC unit forms dihedral angles of 5.9(3)/2.1(3); 19.7(3)/17.6(3)° with the pyrrole and phenol rings for molecules A and B respectively. The main differences between both molecules is the dihedral torsion between rings, their mean planes form dihedral angles of 25.45(15) and 15.38(15)° for the molecules A and B. In the asymmetric unit, molecules are linked by two weak N – H···O hydrogen bonds with set graph-motif

Patent Highlights April–May 2019

Patent Highlights April–May 2019

Correlation between catalysis properties of activated carbon and nature/position of substitution in the aromatic ring of phenol

ABSTRACT The objective of this work is the valorisation of activated carbon as a catalyst for the electrochemical reactions of phenolic compounds in particular: catechol (CC), resorcinol (RS), hydroquinone (HQ) and paracetamol (PCT). For that, the graphite electrode has been modified by activated carbon for the electrochemical study in phosphate buffer. The effect of the nature and position of the substitution in the phenol chain was investigated. Finally, this behaviour was studied simultaneously for the four target compounds.