cas 99-50-3, 3,4-Dihydroxybenzoic acid | Articles data

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Quercetin inhibits advanced glycation end product formation via chelating metal ions, trapping methylglyoxal, and trapping reactive oxygen species
Physiological concentration of Mg2+, Cu2+, and Zn2+ accelerated AGE formation only in glucosemediated conditions, which was effectively inhibited by chelating ligands. Only quercetin (10) inhibited MGO-mediated AGE formation as well as glucoseand ribose-mediated AGE formation among 10 polyphenols (1-10) tested. We performed an additional structure-activity relationship (SAR) study on flavanols (10, 11, 12, 13, and 14). Morin (12) and kaempherol (14) showed inhibitory activity against MGO-mediated AGE formation, whereas rutin (11) and fisetin (13) did not. These observations indicate that 3,5,7,4'-tetrahydroxy and 4-keto groups of 10 are important to yield newly revised mono-MGO adducts (16 and 17) and di-MGO adduct (18) having cyclic hemiacetals, while 3'-hydroxy group is not essential. We propose here a comprehensive inhibitory mechanism of 10 against AGE formation including chelation effect, trapping of MGO, and trapping of reactive oxygen species (ROS), which leads to oxidative degradation of 18 to 3,4-dihydroxybenzoic acid (15) and other fragments.
Bhuiyan, Mohammad Nazrul Islam,Mitsuhashi, Shinya,Sigetomi, Kengo,Ubukata, Makoto
p. 882 - 890
(2017)
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Investigating terephthalate biodegradation: Structural characterization of a putative decarboxylating cis-dihydrodiol dehydrogenase
As a highly coveted precursor molecule, terephthalate (Tph) continues to be used extensively for the production of polyethylene Tph bottles, polyester films, and textile fibers worldwide. Based on its detrimental physiological effects, Tph is now recognized as a serious environmental pollutant. While amenable to biodegradation and, in fact, traditionally neutralized by aerobic microbiological processes, our current lack of understanding of the enzymatic degradation of Tph at the molecular level presents a major impediment in the development of robust bioremediation strategies. The biodegradation of Tph proceeds through a single metabolic intermediate (a cis-dihydrodiol), which is subsequently converted to the end product (protocatechuate) by a decarboxylating cis-dihydrodiol dehydrogenase (TphB). Using iodide single-wavelength anomalous dispersion, we report the first structural characterization of TphB to 1.85 A resolution. Contrary to prior speculations, a fluorescent scan unambiguously shows that TphB coordinates Zn2 + and not Fe 2 +. The molecular architecture of TphB provides a rationale to the primary-level divergence observed between TphB and other cis-dihydrodiol dehydrogenases while explaining its intriguingly close evolutionary clustering with non-dihydrodiol dehydrogenases belonging to the isocitrate/isopropylmalate family of enzymes. Sequence and structural analyses reveal a putative substrate-binding pocket proximal to the bound Zn2 +. In silico substrate modeling in this putative binding pocket suggests a mechanistic sequence relying on H291, K295, and Zn2 + as core mediators of catalytic turnover. Overall, this study reveals novel structural and mechanistic insights into a decarboxylating cis-dihydrodiol dehydrogenase that mediates one of the two catalytic steps in the biodegradation of the environmental pollutant Tph.
Bains, Jasleen,Boulanger, Martin J.,Wulff, Jeremy E.
p. 284 - 293,10
(2012)
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Phenolic compounds from Urtica urens growing in Georgia
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Kavtaradze
p. 314 - 314
(2003)
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Multi-Enzymatic Cascade Reactions for the Synthesis of cis,cis-Muconic Acid
Lignin valorization allows the generation of a number of value-added products such as cis,cis-muconic acid (ccMA), which is widely used for the synthesis of chemicals for the production of biodegradable plastic materials. In the present work, we reported the first multi-enzymatic, one-pot bioconversion process of vanillin into ccMA. In details, we used four sequential reactions catalyzed by xanthine oxidase, O-demethylase LigM (and the tetrahydrofolate-regeneration enzyme methyl transferase MetE), decarboxylase AroY (based on the use of E. coli transformed cells) and catechol 1,2-dioxygenase CatA. The optimized lab-scale procedure allowed to reach, for the first time, the conversion of 5 mM vanillin into ccMA in ～30 h with a 90% yield: this achievement represents an improvement in terms of yields and time when compared to the use of a whole-cell system. This multi-enzymatic system represents a sustainable alternative for the production of a high value added product from a renewable resource. (Figure presented.).
Di Nardo, Giovanna,Gazzola, Silvia,Gilardi, Gianfranco,Pollegioni, Loredano,Rosini, Elena,Valetti, Francesca,Vignali, Elisa
p. 114 - 123
(2021/10/07)

Negative correlations between cultivable and active-yet-uncultivable pyrene degraders explain the postponed bioaugmentation
Bioaugmentation is an effective approach to remediate soils contaminated by polycyclic aromatic hydrocarbons (PAHs), but suffers from unsatisfactory performance in engineering practices, which is hypothetically explained by the complicated interactions between indigenous microbes and introduced degraders. This study isolated a cultivable pyrene degrader (Sphingomonas sp. YT1005) and an active pyrene degrading consortium (Gp16, Streptomyces, Pseudonocardia, Panacagrimonas, Methylotenera and Nitrospira) by magnetic-nanoparticle mediated isolation (MMI) from soils. Pyrene biodegradation was postponed in bioaugmentation with Sphingomonas sp. YT1005, whilst increased by 30.17% by the active pyrene degrading consortium. Pyrene dioxygenase encoding genes (nidA, nidA3 and PAH-RHDα-GP) were enriched in MMI isolates and positively correlated with pyrene degradation efficiency. Pyrene degradation by Sphingomonas sp. YT1005 only followed the phthalate pathway, whereas both phthalate and salicylate pathways were observed in the active pyrene degrading consortium. The results indicated that the uncultivable pyrene degraders were suitable for bioaugmentation, rather than cultivable Sphingomonas sp. YT1005. The negative correlations between Sphingomonas sp. YT1005 and the active-yet-uncultivable pyrene degraders were the underlying mechanisms of bioaugmentation postpone in engineering practices.
Jiang, Bo,Chen, Yating,Xing, Yi,Lian, Luning,Shen, Yaoxin,Zhang, Baogang,Zhang, Han,Sun, Guangdong,Li, Junyi,Wang, Xinzi,Zhang, Dayi
(2021/09/24)

Iron-catalyzed arene C-H hydroxylation
The sustainable, undirected, and selective catalytic hydroxylation of arenes remains an ongoing research challenge because of the relative inertness of aryl carbon-hydrogen bonds, the higher reactivity of the phenolic products leading to over-oxidized by-products, and the frequently insufficient regioselectivity. We report that iron coordinated by a bioinspired L-cystine-derived ligand can catalyze undirected arene carbon-hydrogen hydroxylation with hydrogen peroxide as the terminal oxidant. The reaction is distinguished by its broad substrate scope, excellent selectivity, and good yields, and it showcases compatibility with oxidation-sensitive functional groups, such as alcohols, polyphenols, aldehydes, and even a boronic acid. This method is well suited for the synthesis of polyphenols through multiple carbon-hydrogen hydroxylations, as well as the late-stage functionalization of natural products and drug molecules.
Cheng, Lu,Wang, Huihui,Cai, Hengrui,Zhang, Jie,Gong, Xu,Han, Wei
p. 77 - 81
(2021/10/05)

Thiols Act as Methyl Traps in the Biocatalytic Demethylation of Guaiacol Derivatives
Demethylating methyl phenyl ethers is challenging, especially when the products are catechol derivatives prone to follow-up reactions. For biocatalytic demethylation, monooxygenases have previously been described requiring molecular oxygen which may cause oxidative side reactions. Here we show that such compounds can be demethylated anaerobically by using cobalamin-dependent methyltransferases exploiting thiols like ethyl 3-mercaptopropionate as a methyl trap. Using just two equivalents of this reagent, a broad spectrum of substituted guaiacol derivatives were demethylated, with conversions mostly above 90 %. This strategy was used to prepare the highly valuable antioxidant hydroxytyrosol on a one-gram scale in 97 % isolated yield.
Grimm, Christopher,Kroutil, Wolfgang,Pompei, Simona,Schiller, Christine,Schober, Lukas
supporting information
p. 16906 - 16910
(2021/07/02)

Ni-NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics
Herein, we report a facile method for the synthesis of Ni-NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols usingN-bromosuccinimide (NBS). A remarkablepara-selectivity was achieved for the halogenated products under semi-aqueous conditions. Interestingly, blocking of thepara-position of phenol offeredortho-selective halogenation. In addition, the Ni-NiO nanoparticles catalyzed the oxidative esterification of carbonyl compounds with alcohol, diol or dithiol in the presence of a catalytic amount of NBS. It was observed that the aromatic carbonyls substituted with an electron-donating group favoured nuclear halogenation, whereas an electron-withdrawing group substitution in carbonyl compounds facilitated the oxidation reaction. In addition, the catalyst was magnetically separated and recycled 10 times. The tuned electronic structure at the Ni-NiO heterojunction controlled selectivity and activity as no suchpara-selectivity was observed with commercially available NiO or Ni nanoparticles.
Bhardwaj, Nivedita,Goel, Bharat,Indra, Arindam,Jain, Shreyans K.,Singh, Ajit Kumar,Tripathi, Nancy
p. 14177 - 14183
(2021/08/16)

Method for industrially producing protocatechuic acid
The invention discloses a method for industrially producing protocatechuic acid. According to the invention, vanillic aldehyde is used as a raw material. The method comprises the following steps: firstly, performing catalytic oxidation on the raw material in an organic solvent to obtain 4-hydroxy-3-methoxybenzoic acid; and then removing a methyl group under the action of a demethylation reagent soas to finally obtain a target product, namely protocatechuic acid. The method is simple in process, has separation yield reaching 98% or above (metered by vanillin), enables product purity to reach 99% or above, greatly reduces synthesis cost, and is suitable for industrial large-scale production.
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Paragraph 0034; 0036; 0037; 0039; 0040; 0042

(2020/07/15)

Oxidative metabolism of typical phenolic compounds of Danshen by electrochemistry coupled to quadrupole time-of-flight tandem mass spectrometry
An electrochemistry coupled to online quadrupole time-of-flight tandem mass spectrometry (EC/Q-TOF/MS) was applied to investigate the oxidative transformation and metabolic pathway of five phenolic acids in Danshen sample. Simulation of the phase I oxidative metabolism was carried out in an electrochemical reactor equipped with a glassy carbon working electrode. The phase II reactivity of the generated oxidative products towards biomolecules (such as glutathione) was investigated by ways of covalent adduct formation experiments. The results obtained by EC/MS were compared with well-known in vitro studies by conducting rat liver microsome incubations. Structures of the electrochemically produced metabolites were identified by accurate mass measurement and previously results in vivo metabolites. It was indicated that the electrochemical oxidation was in good accordance with similar products found in vivo experiments. In conclusion, this work confirmed that EC/Q-TOF/MS was a promising analytical tool in the prediction of metabolic transformations of functional foods.
Cao, Jun,Chen, Yan,Dong, Xin,Yang, Juan,Ye, Li-Hong,Zhen, Xiao-Ting,Zheng, Hui
(2020/02/04)

The fate of acylated anthocyanins in mildly heated neutral solution
In neutral solution, anthocyanins acylated by hydroxycinnamic acids typically exhibit attractive blue colors and a higher resistance to color loss compared to their nonacylated homologs. However, they remain vulnerable to a poorly understood combination of oxidative and hydrolytic reactions that strongly contribute to color loss and limits their industrial applications. In this work, the thermal degradation of isolated red cabbage anthocyanins (0, 1 or 2 acyl groups) at pH 7 was investigated by UPLC-DAD-MS (low- and high-resolution). Non-oxidative alterations, including deacylation and intramolecular acyl transfer, were observed and found very dependent on the number and position of the acyl group(s) as well as on the presence of iron ions. At intermediate and advanced thermal degradation, several oxidative mechanisms were evidenced that lead to protocatechuic acid, phloroglucinaldehyde 2-O-glucoside, acylglycosides and derivatives of 2,4,6-trihydroxyphenylacetic acid and 3,5,7-trihydroxycoumarin. Based on the product distribution observed and on the impact of added Fe2+ ions and H2O2, possible degradation mechanisms are discussed. They likely start with a one- or two-electron transfer from the anionic base (a major colored form in neutral solution) to O2. The hydrogen peroxide produced could then further react as an electrophile with the anionic base and/or the hemiketal (major colorless hydrated form). This contribution to understanding the degradation mechanisms of anthocyanins around neutrality can open up new stabilization strategies to extend the range of their food applications to neutral media.
Collins, Thomas M.,Dangles, Olivier,Fenger, Julie-Anne,Robbins, Rebecca J.
(2020/03/23)

Synthesis of Lignin-based Phenol Terminated Hyperbranched Polymer
In this work, we proved the efficient synthesis of a bio-based hyper-branched polyphenol from a modified lignin degradation fragment. Protocatechuic acid was readily obtained from vanillin, a lignin degradation product, via alkaline conditions, and further polymerised to yield high molecular weight hyperbranched phenol terminated polyesters. Vanillic acid was also subjected to similar polymerisation conditions in order to compare polymerisation kinetics and differences between linear and hyperbranched polymers. Overall, protocatechuic acid was faster to polymerise and more thermostable with a degradation temperature well above linear vanillic acid polyester. Both polymers exhibited important radical scavenging activity (RSA) compared to commercial antioxidant and present tremendous potential for antioxidant applications.
Longe, Lionel,Garnier, Gil,Saito, Kei
(2019/10/28)

Exploring the Selective Demethylation of Aryl Methyl Ethers with a Pseudomonas Rieske Monooxygenase
Biocatalytic dealkylation of aryl methyl ethers is an attractive reaction for valorization of lignin components, as well as for deprotection of hydroxy functionalities in synthetic chemistry. We explored the demethylation of various aryl methyl ethers by using an oxidative demethylase from Pseudomonas sp. HR199. The Rieske monooxygenase VanA and its partner electron transfer protein VanB were recombinantly coexpressed in Escherichia coli and they constituted at least 25 % of the total protein content. Enzymatic transformations showed that VanB accepts NADH and NADPH as electron donors. The VanA–VanB system demethylates a number of aromatic substrates, the presence of a carboxylic acid moiety is essential, and the catalysis occurs selectively at the meta position to this carboxylic acid in the aromatic ring. The reaction is inhibited by the by-product formaldehyde. Therefore, we tested three different cascade/tandem reactions for cofactor regeneration and formaldehyde elimination; in particular, conversion was improved by addition of formaldehyde dehydrogenase and formate dehydrogenase. Finally, the biocatalyst was applied for the preparation of protocatechuic acid from vanillic acid, giving a 77 % yield of the desired product. The described reaction may find application in the conversion of lignin components into diverse hydroxyaromatic building blocks and generally offers potential for new, mild methods for efficient unmasking of phenols.
Lanfranchi, Elisa,Trajkovi?, Milo?,Barta, Katalin,de Vries, Johannes G.,Janssen, Dick B.
p. 118 - 125
(2019/01/04)

Heterogeneous Nitrogen-doped Graphene Catalysed HOO? Generation via a Non-radical Mechanism for Base-free Dakin Reaction
A heterogeneous nitrogen-doped graphene catalytic pathway for H2O2 activation to generate alkaline hydrogen peroxide (HOO?) through a non-radical mechanism was reported. Remarkably, the heterogeneous catalytic procedure has been used for the evergreen and environmentally Dakin reaction without using any transition metals, homogeneous bases, ligands, additives or promoters, completely. The study of catalyst structure and catalytic activities indicate that the most active sites are created by the graphitic N atoms at zig-zag edges of the sheets. In addition, N as dopant element changes the reactivity of the neighbour C atoms, and leads to the formation of carbon-hydroperoxide (C?(HOOH)) and C?O* (C?O?) transition state species on the graphene surface in catalytic the reaction. (Figure presented.).
Sun, Wei,Gao, Lingfeng,Sun, Xu,Yang, Hua,Zheng, Gengxiu
supporting information
p. 5210 - 5216
(2019/11/03)

Cytochrome P450 CYP199A4 from Rhodopseudomonas palustris Catalyzes Heteroatom Dealkylations, Sulfoxidation, and Amide and Cyclic Hemiacetal Formation
The cytochrome P450 enzymes execute a range of selective oxidative biotransformations across many biological systems. The bacterial enzyme CYP199A4 catalyzes the oxidative demethylation of 4-methoxybenzoic acid. The benzoic acid moiety of the molecule binds in the active site of the enzyme such that the functional group at the para-position is held close to the heme iron. Therefore, CYP199A4 has the potential to catalyze alternative monooxygenase reactions with different para-substituted benzoic acid substrates such as thioethers and alkylamines. The oxidation of 4-methyl- and 4-ethyl-thiobenzoic acids by CYP199A4 resulted in sulfur oxidation. 4-Ethylthiobenzoic acid sulfoxidation and 4-ethylbenzoic acid hydroxylation by CYP199A4 occurred with high enantioselectivity (>74% enantiomeric excess). By way of contrast, CYP199A4 catalyzed exclusive oxidative N-demethylation over N-oxide formation with 4-methyl- and 4-dimethylaminobenzoic acids. Unexpectedly acetamide formation by CYP199A4 competes with dealkylation in the turnover of 4-ethyl- and diethyl-aminobenzoic acids. No oxidative dealkylation was observed with 3,4-ethylenedioxybenzoic with only hydroxylation to form a cyclic hemiacetal being detected. The X-ray crystal structures of four substrate-bound forms of the enzyme were solved and revealed subtle changes in the location of the para substituent which, when combined with the reactivity of the substituents, provided a basis for understanding the changes in selectivity. Furthermore, in the 4-ethylthiobenzoic acid-bound structure, the active site residue Phe298 moves to accommodate the substituent which points away from the heme iron. As such, the CYP199A4 enzyme provides ready access to a combination of structural, binding, and activity data with which to study a variety of reactions which are catalyzed by the P450 superfamily of enzymes.
Coleman, Tom,Wong, Siew Hoon,Podgorski, Matthew N.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
p. 5915 - 5927
(2018/05/29)

Exploring the oxidation and iron binding profile of a cyclodextrin encapsulated quercetin complex unveiled a controlled complex dissociation through a chemical stimulus
Background: Flavonoids possess a rich polypharmacological profile and their biological role is linked to their oxidation state protecting DNA from oxidative stress damage. However, their bioavailability is hampered due to their poor aqueous solubility. This can be surpassed through encapsulation to supramolecular carriers as cyclodextrin (CD). A quercetin- 2HP-β-CD complex has been formerly reported by us. However, once the flavonoid is in its 2HP-β-CD encapsulated state its oxidation potential, its decomplexation mechanism, its potential to protect DNA damage from oxidative stress remained elusive. To unveil this, an array of biophysical techniques was used. Methods: The quercetin-2HP-β-CD complex was evaluated through solubility and dissolution experiments, electrochemical and spectroelectrochemical studies (Cyclic Voltammetry), UV–Vis spectroscopy, HPLC-ESI-MS/MS and HPLC-DAD, fluorescence spectroscopy, NMR Spectroscopy, theoretical calculations (density functional theory (DFT)) and biological evaluation of the protection offered against H2O2-induced DNA damage. Results: Encapsulation of quercetin inside the supramolecule's cavity enhanced its solubility and retained its oxidation profile. Although the protective ability of the quercetin-2HP-β-CD complex against H2O2 was diminished, iron serves as a chemical stimulus to dissociate the complex and release quercetin. Conclusions: We found that in a quercetin-2HP-β-CD inclusion complex quercetin retains its oxidation profile similarly to its native state, while iron can operate as a chemical stimulus to release quercetin from its host cavity. General significance: The oxidation profile of a natural product once it is encapsulated in a supramolecular carrier was unveiled as also it was discovered that decomplexation can be triggered by a chemical stimilus.
Diamantis, Dimitrios A.,Ramesova, Sarka,Chatzigiannis, Christos M.,Degano, Ilaria,Gerogianni, Paraskevi S.,Karadima, Konstantina E.,Perikleous, Sonia,Rekkas, Dimitrios,Gerothanassis, Ioannis P.,Galaris, Dimitrios,Mavromoustakos, Thomas,Valsami, Georgia,Sokolova, Romana,Tzakos, Andreas G.
p. 1913 - 1924
(2018/07/03)

Sphingobacterium sp. T2 Manganese Superoxide Dismutase Catalyzes the Oxidative Demethylation of Polymeric Lignin via Generation of Hydroxyl Radical
Sphingobacterium sp. T2 contains two extracellular manganese superoxide dismutase enzymes which exhibit unprecedented activity for lignin oxidation but via an unknown mechanism. Enzymatic treatment of lignin model compounds gave products whose structures were indicative of aryl-Cα oxidative cleavage and demethylation, as well as alkene dihydroxylation and alcohol oxidation. 18O labeling studies on the SpMnSOD-catalyzed oxidation of lignin model compound guiaiacylglycerol-β-guaiacyl ether indicated that the an oxygen atom inserted by the enzyme is derived from superoxide or peroxide. Analysis of an alkali lignin treated by SpMnSOD1 by quantitative 31P NMR spectroscopy demonstrated 20-40% increases in phenolic and aliphatic OH content, consistent with lignin demethylation and some internal oxidative cleavage reactions. Assay for hydroxyl radical generation using a fluorometric hydroxyphenylfluorescein assay revealed the release of 4.1 molar equivalents of hydroxyl radical by SpMnSOD1. Four amino acid replacements in SpMnSOD1 were investigated, and A31H or Y27H site-directed mutant enzymes were found to show no lignin demethylation activity according to 31P NMR analysis. Structure determination of the A31H and Y27H mutant enzymes reveals the repositioning of an N-terminal protein loop, leading to widening of a solvent channel at the dimer interface, which would provide increased solvent access to the Mn center for hydroxyl radical generation.
Rashid, Goran M. M.,Zhang, Xiaoyang,Wilkinson, Rachael C.,Fül?p, Vilmos,Cottyn, Betty,Baumberger, Stéphanie,Bugg, Timothy D. H.
p. 2920 - 2929
(2018/10/20)

Mechanistic studies of hydrogen-peroxide-mediated anthocyanin oxidation
The oxidation of cyanidin-3-O-glucoside by hydrogen peroxide was investigated in a range of solvents. The reaction products had chemical structures identical to those formed by the reaction of this compound with the alkylperoxyl radical 2,2?-azobis(2,4-dimethyl)valeronitrile. A plausible oxidation mechanism was proposed based on the obtained reaction products, and this mechanism was confirmed by HPLC–MS experiments using 18O-labeled reagents. Further, the reaction conditions were found to influence both the reaction rate and the products formed during the transformation, which validated the proposed mechanism.
Satake, Ryuya,Yanase, Emiko
supporting information
p. 6187 - 6191
(2018/09/17)

Carbodiimides as Acid Scavengers in Aluminum Triiodide Induced Cleavage of Alkyl Aryl Ethers
A practical procedure for the cleavage of alkyl aryl ethers containing labile functional groups has been developed using aluminum triiodide as the ether cleaving reagent. Carbodiimides, typically used as dehydration reagents for the coupling of amines and carboxylic acids to yield amide bonds, are found to be effective hydrogen iodide scavengers that prevent acid-labile groups from deterioration. The method is applicable to variant alkyl aryl ethers such as eugenol, vanillin, ortho -vanillin and methyl eugenol. Suitable substrates are not limited to alkyl o -hydroxyphenyl ethers.
Sang, Dayong,Wang, Jiahui,Zheng, Yun,He, Jianyuan,Yuan, Caili,An, Qing,Tian, Juan
p. 2721 - 2726
(2017/06/13)

Ether bond breakage method for phenylalkyl ethers
The invention discloses an ether bond breakage method for phenylalkyl ethers. The method comprises the step: subjecting the phenylalkyl ethers to an ether bond breakage reaction at the temperature of -20 DEG C to reflux temperature in an organic solvent in the presence of aluminum triiodide and carbodiimide, so as to produce phenols and derivatives thereof. The method is moderate in conditions, simple and convenient in operation, high in yield and wide in applicable phenylalkyl ether range.
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Paragraph 0120-0122

(2017/07/19)

Pyridine Improves Aluminum Triiodide Induced Selective Cleavage of Alkyl o -Hydroxyphenyl Ethers: A Practical and Efficient Procedure for the Preparation of Hydroxychavicol by Demethylation of Eugenol
Demethylation of eugenol with aluminum triiodide is complicated by an unexpected hydrogenation side reaction. The hydrogenation proceeds through a cascade deprotonation, hydroiodination, and hydrogen-halogen exchange process, and can be prevented by suppressing the hydroiodination in advance. A practical demethylation procedure is thus developed that delivers hydryoxychavicol in essentially quantitative yield by using pyridine as an additive. The method is selective towards cleaving alkyl o-hydroxyphenyl ethers and is compatible with a variety of functional groups.
Sang, Dayong,Yao, Ming,Tian, Juan,Chen, Xiaoman,Li, Li,Zhan, Hongju,You, Linhong
p. 138 - 142
(2016/12/26)

Ether bond rupturing method for ortho-hydroxyl phenyl alkyl ether
The invention discloses an ether bond rupturing method for ortho-hydroxyl phenyl alkyl ether. The method comprises the following steps that in a solvent, an ether bond rupturing reaction occurs to ortho-hydroxyl aryl alky ether at the temperature ranging from minus 20 DEG C to the catalyst reflux temperature under the existence of alkali and a catalyst aluminum triiodide, and catechol and derivatives thereof are generated. The method is simple, reaction conditions are simple, and operation is easy; besides, the yield is high, and the applicable ortho-hydroxyl phenyl alkyl ether range is wide.
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Paragraph 0069; 0070; 0071; 0072

(2017/05/27)

Solar light-induced degradation of ethyl paraben with CuOx/BiVO4: Statistical evaluation of operating factors and transformation by-products
In this work, the solar light-induced photocatalytic degradation of ethyl paraben (EP) was studied using CuOx/BiVO4 with 0.75 wt.% copper loading, a relatively new photocatalyst that can exploit a large portion of the solar spectrum. The synthesized catalyst had a primary crystallite size of ca 37 nm, a specific surface area of 1 m2/g and a direct bandgap of 2.3 eV. A factorial design methodology was implemented to evaluate the importance of EP concentration (500–1500 μg/L), catalyst concentration (100–500 mg/L), reaction time (10–60 min), the presence of radical scavengers (pure water or 500 mg/L bicarbonates) and initial solution pH (3–9) on EP removal. All individual effects were statistically significant and so was the second-order interaction of EP concentration with reaction time. Interestingly and differently from the majority of photocatalytic studies, the presence of bicarbonates promotes the photocatalytic degradation of ethyl paraben. The photocatalytic activity drops from 98% to 79% after five consecutive runs, possibly due to accumulation of oxidation by-products. Liquid chromatography-time of flight mass spectrometry (LC-TOF-MS) revealed that EP degradation occurs mainly via dealkylation followed by hydroxylation reactions and the formation of methyl paraben, 4-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid as primary transformation by-products.
Petala, Athanasia,Bontemps, Remi,Spartatouille, Antoine,Frontistis, Zacharias,Antonopoulou, Maria,Konstantinou, Ioannis,Kondarides, Dimitris I.,Mantzavinos, Dionissios
p. 122 - 131
(2016/11/16)

Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway
In the present study, decolorization and mineralization of a cationic dye, Rhodamine 6G (Rh6G), has been carried out using hydrodynamic cavitation (HC). Two cavitating devices such as slit and circular venturi were used to generate cavitation in HC reactor. The process parameters such as initial dye concentration, solution pH, operating inlet pressure, and cavitation number were investigated in detail to evaluate their effects on the decolorization efficiency of Rh6G. Decolorization of Rh6G was marginally higher in the case of slit venturi as compared to circular venturi. The kinetic study showed that decolorization and mineralization of the dye fitted first-order kinetics. The loadings of H2O2 and ozone have been optimized to intensify the decolorization and mineralization efficiency of Rh6G using HC. Nearly 54% decolorization of Rh6G was obtained using a combination of HC and H2O2 at a dye to H2O2 molar ratio of 1:30. The combination of HC with ozone resulted in 100% decolorization in almost 5-10 min of processing time depending upon the initial dye concentration. To quantify the extent of mineralization, total organic carbon (TOC) analysis was also performed using various processes and almost 84% TOC removal was obtained using HC coupled with 3 g/h of ozone. The degradation by-products formed during the complete degradation process were qualitatively identified by liquid chromatography-mass spectrometry (LC-MS) and a detailed degradation pathway has been proposed.
Rajoriya, Sunil,Bargole, Swapnil,Saharan, Virendra Kumar
p. 183 - 194
(2016/06/06)

Solar photocatalytic decomposition of ethyl paraben in zinc oxide suspensions
The photocatalytic degradation of ethyl paraben (EP) in zinc oxide (ZnO) suspensions under simulated solar radiation was investigated. The effect of EP concentration (500–1500 μg/L), ZnO concentration (100–500 mg/L), reaction time (3–9 min), initial pH (3–9), light intensity (7.3 10?7–1.1 10?6 einstein/(L.s)) and the water matrix (0–10 mg/L of humic acid) on degradation was evaluated implementing a factorial design methodology. Of the six variables tested, EP concentration, ZnO concentration, reaction time and the water matrix were found to be statistically significant variables, and also important was the second order interaction of EP concentration with reaction time. With the exception of the water matrix, all other effects were positive with respect to the concentration of EP removed. Experiments at increased EP concentration (20 mg/L) were performed to identify transformation products (TPs) and assess the extent of mineralization. LC-TOF-MS analysis revealed the formation of seven early-stage TPs through hydroxylation and dealkylation reactions and a plausible reaction pathway was proposed. Besides the identified TPs, other unidentified TPs were also formed as has been verified measuring the extent of mineralization and performing a carbon balance in the liquid phase. EP at 20 mg/L exhibited mild estrogenic activity, which was partially removed upon oxidation. The stability of ZnO was evaluated measuring the extent of zinc leaching, which was just 1.5%; moreover, ZnO was found to be more active than reference P25 TiO2 for EP degradation and mineralization.
Frontistis, Zacharias,Antonopoulou, Maria,Venieri, Danae,Dailianis, Stefanos,Konstantinou, Ioannis,Mantzavinos, Dionissios
p. 139 - 148
(2016/11/16)

Ethyl acetate as a co-solvent and sacrificial ester in the aluminum triiodide promoted chemoselective demethylation of methyl vanillate
A synthetic approach towards methyl protocatechuate via chemoselective ether cleavage of methyl vanillate without affecting the carboxylate group is disclosed utilizing a ternary reagent system consisting of aluminum triiodide, 1,3-diisopropylcarbodiimide and ethyl acetate. Ethyl acetate serves as a co-solvent and sacrificial ester. Methyl isovanillate, ethyl vanillate and methyl feruate were analogously demethylated to give methyl protocatechuate, ethyl protocatechuate and methyl caffeate, respectively, in fair to excellent yields.
Tian, Juan,Yi, Cuicui,Fang, Huasheng,Sang, Dayong,He, Zhoujun,Wang, Jiahui,Gan, Yongjiang,An, Qing
p. 3522 - 3524
(2017/10/06)

Plasma-Induced Degradation of Quercetin Associated with the Enhancement of Biological Activities
Nonthermal plasma is a promising technology to improve the safety and to extend the shelf-life of various minimally processed foods. However, research on plasma-induced systemic degradation related to changes in chemical structure and biological activity is still very limited. In this study, the enhancement of biological activity and the mechanism of degradation of the most common type of flavonol, quercetin, induced by a dielectric barrier discharge (DBD) plasma were investigated. Quercetin is dissolved in methanol and exposed to nonthermal DBD plasma for 5, 10, 20, and 30 min. The quercetin treated with the plasma for 20 min showed rapidly increased α-glucosidase inhibitory and radical scavenging activities compared to those of parent quercetin. The structures of the degradation products 1-3 from the quercetin treated with the plasma for 20 min were isolated and characterized by interpretation of their spectroscopic data. Among the generated products, (±)-alphitonin (1) exhibited significantly improved antidiabetic and antioxidant properties compared to those of the parent quercetin. The antidiabetic and antioxidant properties were measured by α-glucosidase inhibition and 1,1-diphenyl-2-picrylhydrazyl radical scavenging assays. These results suggested that structural changes in quercetin induced by DBD plasma might be attributable to improving the biological activity.
Kim, Tae Hoon,Lee, Jaemin,Kim, Hyun-Joo,Jo, Cheorun
p. 6929 - 6935
(2017/08/22)

Regioselective para-Carboxylation of Catechols with a Prenylated Flavin Dependent Decarboxylase
The utilization of CO2 as a carbon source for organic synthesis meets the urgent demand for more sustainability in the production of chemicals. Herein, we report on the enzyme-catalyzed para-carboxylation of catechols, employing 3,4-dihydroxybenzoic acid decarboxylases (AroY) that belong to the UbiD enzyme family. Crystal structures and accompanying solution data confirmed that AroY utilizes the recently discovered prenylated FMN (prFMN) cofactor, and requires oxidative maturation to form the catalytically competent prFMNiminium species. This study reports on the in vitro reconstitution and activation of a prFMN-dependent enzyme that is capable of directly carboxylating aromatic catechol substrates under ambient conditions. A reaction mechanism for the reversible decarboxylation involving an intermediate with a single covalent bond between a quinoid adduct and cofactor is proposed, which is distinct from the mechanism of prFMN-associated 1,3-dipolar cycloadditions in related enzymes.
Payer, Stefan E.,Marshall, Stephen A.,B?rland, Natalie,Sheng, Xiang,Reiter, Tamara,Dordic, Andela,Steinkellner, Georg,Wuensch, Christiane,Kaltwasser, Susann,Fisher, Karl,Rigby, Stephen E. J.,Macheroux, Peter,Vonck, Janet,Gruber, Karl,Faber, Kurt,Himo, Fahmi,Leys, David,Pavkov-Keller, Tea,Glueck, Silvia M.
p. 13893 - 13897
(2017/10/09)

Polypeptides having peroxygenase activity and polynucleotides encoding same
The present invention relates to isolated polypeptides having peroxygenase activity, and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
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Page/Page column 34-35

(2016/08/07)

Polypeptides having peroxygenase activity and polynucleotides encoding same
The present invention relates to isolated polypeptides having peroxygenaseactivity, and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
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Page/Page column 35

(2016/08/29)

Sonochemical degradation of ethyl paraben in environmental samples: Statistically important parameters determining kinetics, by-products and pathways
The sonochemical degradation of ethyl paraben (EP), a representative of the parabens family, was investigated. Experiments were conducted at constant ultrasound frequency of 20 kHz and liquid bulk temperature of 30 °C in the following range of experimental conditions: EP concentration 250-1250 μg/L, ultrasound (US) density 20-60 W/L, reaction time up to 120 min, initial pH 3-8 and sodium persulfate 0-100 mg/L, either in ultrapure water or secondary treated wastewater. A factorial design methodology was adopted to elucidate the statistically important effects and their interactions and a full empirical model comprising seventeen terms was originally developed. Omitting several terms of lower significance, a reduced model that can reliably simulate the process was finally proposed; this includes EP concentration, reaction time, power density and initial pH, as well as the interactions (EP concentration) × (US density), (EP concentration) × (pHo) and (EP concentration) × (time). Experiments at an increased EP concentration of 3.5 mg/L were also performed to identify degradation by-products. LC-TOF-MS analysis revealed that EP sonochemical degradation occurs through dealkylation of the ethyl chain to form methyl paraben, while successive hydroxylation of the aromatic ring yields 4-hydroxybenzoic, 2,4-dihydroxybenzoic and 3,4-dihydroxybenzoic acids. By-products are less toxic to bacterium V. fischeri than the parent compound.
Papadopoulos, Costas,Frontistis, Zacharias,Antonopoulou, Maria,Venieri, Danae,Konstantinou, Ioannis,Mantzavinos, Dionissios
p. 62 - 70
(2015/12/18)

Conversion of Simple Cyclohexanones into Catechols
A novel I2-catalyzed direct conversion of cyclohexanones to substituted catechols under mild and simple conditions has been described. This novel transformation is remarkable with the multiple oxygenation and dehydrogenative aromatization processes enabled just by using DMSO as the solvent, oxidant, and oxygen source. This metal-free and simple system demonstrates a versatile protocol for the synthesis of highly valuable substituted catechols and therefore streamlines the synthesis and modification of biologically important molecules for drug discovery.
Liang, Yu-Feng,Li, Xinyao,Wang, Xiaoyang,Zou, Miancheng,Tang, Conghui,Liang, Yujie,Song, Song,Jiao, Ning
supporting information
p. 12271 - 12277
(2016/09/28)

On the difference in decomposition of taxifolin and luteolin vs. fisetin and quercetin in aqueous media
Abstract: The decomposition of flavonols quercetin and fisetin, flavone luteolin and flavanone taxifolin was studied in slightly alkaline solution under ambient conditions. The study was based on spectrophotometry and high-pressure liquid chromatography. Products formed by atmospheric oxygen oxidation and hydrolysis were identified by HPLC–DAD and HPLC–ESI-MS/MS. Only small differences in the chemical structure of flavonoids resulted in extremely variable oxidation pathways and products. Oxidation of flavonols led to the formation of both a benzofuranone derivative and several open structures. On the contrary, the benzofuranone derivative was not found as a product of taxifolin and luteolin oxidative decomposition. These compounds were oxidized to their hydroxylated derivatives and typical open structures. Quercetin was not identified as a possible oxidation product of taxifolin. Graphical Abstract: [Figure not available: see fulltext.]
Sokolová, Romana,Rame?ová, ?árka,Kocábová, Jana,Kolivo?ka, Viliam,Degano, Ilaria,Pitzalis, Emanuela
p. 1375 - 1383
(2016/08/12)

Modification of quercetin with l-cysteine by horseradish peroxidase
Horseradish peroxidase is a well-known member of the peroxidase family that catalyzes oxidation of flavonoids and phenolic substrates to free phenoxyl or semiquinone radicals. Aim of this study was to investigate in vitro oxidation of quercetin by horseradish peroxidase in the presence of l-cysteine as nucleophilic agent, and its influence on previously formed semiquinone- and quinone-type metabolites. The obtained results showed that in the reaction without l-cysteine several products were present, such as quercetin quinone methide, phloroglucinol carboxylic acid, protocatechuic acid, as well as quercetin heterodimer and derivates of quercetin heterodimer. On the other hand, in the presence of l-cysteine only three products were obtained, quercetin quinone methide and two new isomeric mono-cysteine derivatives of quercetin with mass exp. m/z 420.04 ± 0.1 [quercetin + cysteine–H]– (theor. m/z 420.0389 [quercetin + cysteine–H]–).
Savic, Sasa,Keckes, Silvio,Petronijevic, Zivomir
p. 226 - 235
(2016/12/16)

CYP199A4 catalyses the efficient demethylation and demethenylation of para-substituted benzoic acid derivatives
The cytochrome P450 enzyme CYP199A4, from Rhodopseudomonas palustris strain HaA2, can efficiently demethylate 4-methoxybenzoic acid via hemiacetal formation and subsequent elimination of formaldehyde. Oxidative demethylation of a methoxy group para to the carboxyl moiety is strongly favoured over reaction at one in the ortho or meta positions. Dimethoxybenzoic acids containing a para-methoxy group were also efficiently demethylated exclusively at the para position. The presence of additional methoxy substituents reduces the substrate binding affinity and the activity compared to 4-methoxybenzoic acid. The addition of the smaller hydroxy group to the ortho or meta positions or of a nitrogen heteroatom in the aromatic ring of the 4-methoxybenzoate skeleton was better tolerated by the enzyme and these analogues were also readily demethylated. There was no evidence of methylenedioxy ring formation with 3-hydroxy-4-methoxybenzoic acid, an activity which is observed with certain plant CYP enzymes with analogous substrates. CYP199A4 is also able to deprotect the methylenedioxy group of 3,4-(methylenedioxy)benzoic acid to yield 3,4-dihydroxybenzoic acid and formic acid. This study defines the substrate range of CYP199A4 and reveals that substrates without a para substituent are not oxidised with any significant activity. Therefore para-substituted benzoic acids are ideal substrate scaffolds for the CYP199A4 enzyme and will aid in the design of optimised probes to investigate the mechanism of this class of enzymes. They also allow an assessment of the potential of CYP199A4 for synthetic biocatalytic processes involving selective oxidative demethylation or demethenylation.
Coleman, Tom,Chao, Rebecca R.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
p. 52007 - 52018
(2015/06/25)

Improved selectivity of the production of vanilloids in a recombinant unicellular host
The present invention relates to methods for producing vanilloid compounds in a recombinant host, and in particular for converting a protocatechuic aldehyde into a substantially pure vanilloid. It further relates to novel yeast strains that are suitable for producing such vanilloid compounds.
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Paragraph 0206-0210

(2016/01/11)

Electrophilicity and nucleophilicity of commonly used aldehydes
The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
Pratihar, Sanjay
p. 5781 - 5788
(2014/07/22)

Inclusion complex containing epoxy resin composition for semiconductor encapsulation
The invention is an epoxy resin composition for sealing a semiconductor, including (A) an epoxy resin and (B) a clathrate complex. The clathrate complex is one of (b1) an aromatic carboxylic acid compound, and (b2) at least one imidazole compound represented by formula (II): wherein R2 represents a hydrogen atom, C1-C10 alkyl group, phenyl group, benzyl group or cyanoethyl group, and R3 to R5 represent a hydrogen atom, nitro group, halogen atom, C1-C20 alkyl group, phenyl group, benzyl group, hydroxymethyl group or C1-C20 acyl group. The composition has improved storage stability, retains flowability when sealing, and achieves an effective curing rate applicable for sealing delicate semiconductors.
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(2014/03/21)

Application of photoactive electrospun nanofiber materials with immobilized meso-tetraphenylporphyrin for parabens photodegradation
The pollution of aqueous environment by trace amounts of anthropogenic chemical substances has a hazardous impact on regular development of plants and animals as well as on human health. The paper presents the results of studies on the heterogeneous degradation of butyl- and benzylparaben in aqueous solutions using photochemically catalyzed processes. Meso-tetraphenylporphyrin (TPP) was immobilized in the polyurethane nanofiber material by electro-spinning method. The xenon lamp was used as a simulated sunlight source. The influence of various process parameters on reaction rate was investigated. The reuse of the carrier with the immobilized photosensitizer was examined. The major role of the singlet oxygen (1Δg) during the photodegradation was proved by using sodium azide and radical scavengers. The adsorption isotherms of parabens onto nanofiber material were determined using BET model. The kinetic study showed that the heterogeneous photodegradation of parabens could be modeled using Langmuir-Hinshelwood model and rate constants have been reported. The reaction pathway for the photodegradation of parabens via 1Δg was proposed.
Gmurek,Bizukoj?,Mosinger,Ledakowicz
p. 160 - 167
(2015/02/19)

Novel oxidation products of cyanidin 3-O-glucoside with 2,2′-azobis-(2,4-dimethyl)valeronitrile and evaluation of anthocyanin content and its oxidation in black rice
The radical oxidation mechanism of anthocyanin derivatives was investigated by the reaction of cyanidin 3-O-glucoside in the presence of radical initiator 2,2′-azobis-(2,4-dimethyl)valeronitrile (AMVN) in EtOH and aqueous CH 3CN. Six different oxidation products were isolated, depending on the solvent employed. These products were identified using NMR spectroscopy and multistep derivatisation reactions. Of the products obtained, two novel oxidised anthocyanin derivatives were isolated from black rice under prolonged storage. A radical reaction mechanism is proposed on the basis of these reaction products. Quantification of oxidised anthocyanins in black rice is demonstrated as a method to verify freshness of the rice.
Kamiya, Haruna,Yanase, Emiko,Nakatsuka, Shin-Ichi
p. 221 - 226
(2014/03/21)

Fenpropathrin biodegradation pathway in bacillus sp. DG-02 and its potential for bioremediation of pyrethroid-contaminated soils
The widely used insecticide fenpropathrin in agriculture has become a public concern because of its heavy environmental contamination and toxic effects on mammals, yet little is known about the kinetic and metabolic behaviors of this pesticide. This study reports the degradation kinetics and metabolic pathway of fenpropathrin in Bacillus sp. DG-02, previously isolated from the pyrethroid-manufacturing wastewater treatment system. Up to 93.3% of 50 mg L-1 fenpropathrin was degraded by Bacillus sp. DG-02 within 72 h, and the degradation rate parameters qmax, Ks, and K i were determined to be 0.05 h-1, 9.0 mg L-1, and 694.8 mg L-1, respectively. Analysis of the degradation products by gas chromatography-mass spectrometry led to identification of seven metabolites of fenpropathrin, which suggest that fenpropathrin could be degraded first by cleavage of its carboxylester linkage and diaryl bond, followed by degradation of the aromatic ring and subsequent metabolism. In addition to degradation of fenpropathrin, this strain was also found to be capable of degrading a wide range of synthetic pyrethroids including deltamethrin, λ-cyhalothrin, β-cypermethrin, β-cyfluthrin, bifenthrin, and permethrin, which are also widely used insecticides with environmental contamination problems with the degradation process following the first-order kinetic model. Bioaugmentation of fenpropathrin-contaminated soils with strain DG-02 significantly enhanced the disappearance rate of fenpropathrin, and its half-life was sharply reduced in the soils. Taken together, these results depict the biodegradation mechanisms of fenpropathrin and also highlight the promising potentials of Bacillus sp. DG-02 in bioremediation of pyrethroid-contaminated soils.
Chen, Shaohua,Chang, Changqing,Deng, Yinyue,An, Shuwen,Dong, Yi Hu,Zhou, Jianuan,Hu, Meiying,Zhong, Guohua,Zhang, Lian-Hui
p. 2147 - 2157
(2014/04/03)

On the thermal degradation of anthocyanidins: Cyanidin
Cyanidin was studied by direct pH jumps (from equilibrated solutions at very low pH values to higher pH values) and reverse pH jumps (from equilibrated or not equilibrated solutions at higher pH values to very low ones). The kinetic steps of the direct and reverse pH jumps were followed by stopped flow, absorption spectroscopy and HPLC, at different timescales. The pH dependent rate constant of the slower kinetic process to reach the equilibrium follows a bell shaped curve as described for many synthetic flavylium compounds. Unlike anthocyanins, it was proved that there is no pH dependent reversibility in the system, since the chalcone suffers an irreversible degradation process. The mathematical expression to describe the bell shaped behaviour was deduced. These results contribute to explain why in plants glycosylation is crucial for the stabilization of the anthocyanins.
Cabrita, Luis,Petrov, Vesselin,Pina, Fernando
p. 18939 - 18944
(2014/05/20)

Oxidation of aromatic aldehydes with potassium bromate-bromide reagent and an acidic catalyst
We report herein an easy oxidation procedure for converting aromatic aldehydes to aromatic carboxylic acids by use of a combination of commercially and readily available potassium bromate with potassium bromide in the presence of hydrochloric acid catalyst.
Sharma,Robert, Alice R.
p. 3251 - 3254
(2013/09/23)

SMALL MOLECULE MALARIAL ALDOLASE-TRAP ENHANCERS AND GLIDEOSOME INHIBITORS
In one aspect, the present invention relates to a method of identifying compounds useful in modifying the activity of Aldolase. The method includes providing a first model comprising Aldolase or residues of the amino acid sequence corresponding to SEQ ID NO: 1 said residues being at amino acid positions selected from the group consisting of 10-13, 26, 27, 29, 30, 31, 32, 33, 37, 39, 40, 41, 43, 44, 47, 48, 51, 52, 60, 63, 66, 79, 84, 85, 92, 93, 103, 106-109, 112-117, 138, 142, 146, 148, 151, 153, 179, 182, 183, 185, 186, 194, 196, 197, 198, 199, 208, 226-228, 231- 269, 270, 272, 277-283, 285-289, 294, 295, 297-299, 301-304, 306-310, 312, 313, 316, 317, 319, 321, 323, 326, 330, 344, 345, and 347, providing one or more candidate compounds, evaluating contact between the candidate compounds and the first model to determine which of the one or more candidate compounds have an ability to bind to and/or fit in the first model, and identifying compounds which, based on said evaluating, have the ability to bind to and/or fit in the first model as compounds potentially useful for modifying the activity of Aldolase. The present invention also discloses compounds and compositions which modify the activity of Aldolase, or a complex between Aldolase and TRAP. Methods of treating or preventing malaria, or an infection by apicomplexan organisms are also disclosed.
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(2013/05/21)

Photo-degradation of trans-caffeic acid in aqueous solution and influence of complexation by metal ions
The photo-degradation of metal complexes of caffeic acid was compared to the photo-degradation of free caffeic acid by using UV-vis spectroscopy and HPLC-ESI-mass spectrometry. This article reports first the determination of the products that are formed from the photo-degradation of trans-caffeic acid in aqueous solution and the investigation of the mechanism by a kinetic approach. The good fit between the model and the experimental concentration profiles confirms the photo-isomerization route of the molecule to cis-caffeic acid which then undergoes a cyclization to form the esculetin photo-product. In addition, it reveals, for the first time, another route of major importance leading to the product vinylcatechol. The presence of oxygen leads to an increase of the photo-isomerization rate. Then we report that metallic cations such as Al(III), Pb(II) and Cu(II) can influence the rate and mechanism of caffeic acid photodegradation. Al(III) ions slow down the photo-degradation whereas Pb(II) and Cu(II) ions have a promoter effect on the production of esculetin. In all cases, the photo-isomerization is reduced by the presence of metal ions and the formation of vinylcatechol does not occur.
Le Person, Anna?g,Lacoste, Anne-Sophie,Cornard, Jean-Paul
p. 10 - 19
(2013/10/22)

A new route to Roflumilast via copper-catalyzed hydroxylation
A new route to Roflumilast, a selective phosphodiesterase type 4 (PDE 4) inhibitor, is described. The synthetic procedure starts from 4-hydroxy-3-iodobenzoic acid to access the key intermediate 3- (cyclopropylmethoxy)-4-(difluoromethoxy)benzoic acid via copper-catalyzed hydroxylation and utilizes amide coupling to accomplish the synthesis of Roflumilast in 80% overall yield. Georg Thieme Verlag KG Stuttgart · New York.
Ni, Feng,Li, Jianqi
p. 3598 - 3602
(2013/02/22)

The influence of the host-guest interaction on the oxidation of natural flavonoid dyes
The influence of the molecular cavity protection on degradation processes of bioorganic compounds quercetin and luteolin used as the original dyes in old tapestries was studied. The degradation processes were studied by electrochemical methods in aqueous media. The products of the exhaustive electrolysis were separated and identified by GC-MS analysis. Cyclic voltammetry characteristics indicate that the inclusion complex is formed. The inclusion affects the redox potentials of both oxidation waves related to the different dissociation forms of the flavonoid molecule. It was shown that decomposition products formed by the oxidation of quercetin are stabilized in the cavity of β-cyclodextrin, including the main oxidation product 2(3',4'- dihydroxybenzoyl)-2,4,6-trihydroxybenzofuran-3(2H)-one. The formation of the 1:1 inclusion complex of luteolin with β-cyclodextrin is supported by the enhancement of fluorescence intensity. In the case of quercetin, a decrease of fluorescence intensity occurs when 1:1 inclusion complex with β-cyclodextrin is formed.
Ramesova, Sarka,Sokolova, Romana,Degano, Ilaria,Hromadova, Magdalena,Gal, Miroslav,Kolivoska, Viliam,Colombini, Maria Perla
experimental part
p. 1651 - 1667
(2012/05/19)

Flavonoids and hydroxycinnamic acids from astragalus asper
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Guzhva
body text
p. 303 - 304
(2010/10/01)

Cloning and heterologous expression of two aryl-aldehyde dehydrogenases from the white-rot basidiomycete Phanerochaete chrysosporium
We identified two aryl-aldehyde dehydrogenase proteins (PcALDH1 and PcALDH2) from the white-rot basidiomycete Phanerochaete chrysosporium. Both PcALDHs were translationally up-regulated in response to exogenous addition of vanillin, one of the key aromatic compounds in the pathway of lignin degradation by basidiomycetes. To clarify the catalytic functions of PcALDHs, we isolated full-length cDNAs encoding these proteins and heterologously expressed the recombinant enzymes using a pET/Escherichia coli system. The open reading frames of both PcALDH1 and PcALDH2 consisted of 1503 nucleotides. The deduced amino acid sequences of both proteins showed high homologies with aryl-aldehyde dehydrogenases from other organisms and contained ten conserved domains of ALDHs. Moreover, a novel glycine-rich motif "GxGxxxG" was located at the NAD+-binding site. The recombinant PcALDHs catalyzed dehydrogenation reactions of several aryl-aldehyde compounds, including vanillin, to their corresponding aromatic acids. These results strongly suggested that PcALDHs metabolize aryl-aldehyde compounds generated during fungal degradation of lignin and various aromatic xenobiotics.
Nakamura, Tomofumi,Ichinose, Hirofumi,Wariishi, Hiroyuki
experimental part
p. 470 - 475
(2011/12/15)

Phytochemical investigation of the fruit peels of Citrus reticulata Blanco
Phytochemical investigation of the fruit peels of Citrus reticulata Blanco (Rutaceae) resulted in the isolation of three new phytoconstituents along with n-hexacosonoic acid. Their structures have been established as 18H-urs-5,11-dien-3-ol-11-one-3-D-gluc
Khan, M. Aasim,Ali,Alam, Prawez
experimental part
p. 610 - 620
(2010/08/20)

New oligomeric proanthocyanidin glycosides platanoside-A and platanoside-B from Platanus orientalis trunk bark
Two new oligomeric proanthocyanidin glycosides were isolated from trunk bark of Platanus orientalis. Their structures and relative configurations were found to be 7-O-β-D-Glcp-(-)-epicatechin-(4β-8)-(-)- epicatechin(4β-8)-(-)-epicatechin-3-O-gallate (plat
Nishanbaev,Khidyrova,Vdovin,Abdullaev,Shakhidoyatov,Aripov
experimental part
p. 357 - 362
(2010/10/03)