- Analysis of Fluorescence Spectra of Citrus Polymethoxylated Flavones and Their Incorporation into Mammalian Cells
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Citrus polymethoxylated flavones (PMFs) influence biochemical cascades in human diseases, yet little is known about how these compounds interact with cells and how these associations influence the actions of these compounds. An innate attribute of PMFs is their ultraviolet-light-induced fluorescence, and the fluorescence spectra of 14 PMFs and 7 PMF metabolites were measured in methanol. These spectra were shown to be strongly influenced by the compounds' hydroxy and methoxy substituents. For a subset of these compounds, the fluorescence spectra were measured when bound to human carcinoma Huh7.5 cells. Emission-wavelength maxima of PMF metabolites with free hydroxyl substituents exhibited 70-80 nm red shifts when bound to the Huh7.5 cells. Notable solvent effects of water were observed for nearly all these compounds, and these influences likely reflect the effects of localized microenvironments on the resonance structures of these compounds when bound to human cells.
- Gon?alves, Danielle R.,Manthey, John A.,Da Costa, Paulo I.,Rodrigues, Marilia C. M.,Cesar, Thais B.
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- Direct comparison of the enzymatic characteristics and superoxide production of the four aldehyde oxidase enzymes present in mouse
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Aldehyde oxidases (AOXs) are molybdoflavoenzymes with an important role in the metabolism and detoxification of heterocyclic compounds and aliphatic as well as aromatic aldehydes. The enzymes use oxygen as the terminal electron acceptor and produce reduced oxygen species during turnover. Four different enzymes, mAOX1, mAOX3, mAOX4, and mAOX2, which are the products of distinct genes, are present in the mouse. A direct and simultaneous comparison of the enzymatic properties and characteristics of the four enzymes has never been performed. In this report, the four catalytically active mAOX enzymes were purified after heterologous expression in Escherichia coli. The kinetic parameters of the four mouse AOX enzymes were determined and compared with the use of six predicted substrates of physiologic and toxicological interest, i.e., retinaldehyde, N1-methylnicotinamide, pyridoxal, vanillin, 4-(dimethylamino)cinnamaldehyde (p-DMAC), and salicylaldehyde. While retinaldehyde, vanillin, p-DMAC, and salycilaldehyde are efficient substrates for the four mouse AOX enzymes, N1-methylnicotinamide is not a substrate of mAOX1 or mAOX4, and pyridoxal is not metabolized by any of the purified enzymes. Overall, mAOX1, mAOX2, mAOX3, and mAOX4 are characterized by significantly different KM and kcat values for the active substrates. The four mouse AOXs are also characterized by quantitative differences in their ability to produce superoxide radicals. With respect to this last point, mAOX2 is the enzyme generating the largest rate of superoxide radicals of around 40% in relation to moles of substrate converted, and mAOX1, the homolog to the human enzyme, produces a rate of approximately 30% of superoxide radicals with the same substrate.
- Kücükg?ze, G?khan,Terao, Mineko,Garattini, Enrico,Leimkühler, Silke
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- Two lignans and an aryl alkanone from Myristica dactyloides
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Chemical investigation of the hot hexane extract of the stem bark of Myristica dactyloides has resulted in the isolation of two new lignans, rel- (8S,8'R)-dimethyl-(7S,7'R)-bis(3,4-methylenedioxyphenyl)tetrahydrofuran and rel-(8R,8'R)-dimethyl-(7S,7'R)-bis(3,4-methylenedioxyphenyl)tetrahydrofuran, a new diaryl alkanone, 1-(2,6-dihydroxyphenyl)-9-(4-hydroxy-3- methoxyphenyl)nonan-1-one, sitosterol and six other previously reported aryl alkanones. The structures of the new compounds were deduced from their spectral data and chemical transformations.
- Herath, H. M. T. Bandara,Priyadarshani, A. M. Anoma
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- A new glucoside with a potent α-glucosidase inhibitory activity from Lycium schweinfurthii
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A new glucoside, 3-methoxy-4-O-β-D-glucopyranosyl-methyl benzoate, has been isolated from Lycium schweinfurthii along with five known compounds through bioactivity guided fractionation of the total plant methanolic extract towards α-glucosidase inhibitory activity. All the isolated compounds were tested for their inhibitory effect on α-glucosidase enzyme. As a result, four of them showed a potent inhibitory activity and thus constitute a therapeutic approach to decrease postprandial hyperglycemia in diabetic patients.
- Elbermawi, Ahmed,Halim, Ahmed F.,Mansour, El-Sayed S.,Ahmad, Kadria F.,Ashour, Ahmed,Amen, Yhiya,Shimizu, Kuniyoshi
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- Demethoxylation and hydroxylation of methoxy- and hydroxybenzoic acids by OH-radicals. Processes of potential importance for food irradiation
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The hydroxylation process for methoxy- and hydroxy-benzoic acids (MBA, HBA) induced by γ-radiation is compared. 2-, 3-, and 4-methoxybenzoic acid as well as 3-hydroxybenzoic acid have been irradiated in N2O and aerated solutions up to 1.5 kGy. The products were analyzed by HPLC. The results for 2- and 4-HBA have been taken from literature data. The OH·-adduct distribution is generally the same for the hydroxy- as well as for the methoxy-benzoic acid isomers. With both 4-HBA and 4-MBA more than 65% C3-adducts and about 15% C4-adducts are formed, which could be proved by their reactions with K3 Fe(CN)6. Oxidation of the nonipso-adducts of 3-HBA and 3-MBA results in 84 and 87% of the corresponding phenols. Whereas in N2O-saturated solutions only part of the OH·-radicals leads to substrate decomposition, in the presence of air, the degradation of both kinds of compounds is equivalent to [OH·]. The nonipso OH·-adducts of the HBAs are converted into 68-77% hydroxylation products. With the MBAs, the hydroxylation process is ≤10%. This is attributed to different decay pathways of the peroxyl radicals, intermediates formed by O2 addition to the OH·-adducts. The hydroxyperoxycyclohexadienyl radicals of the HBAs decay mainly by HO2· elimination to the corresponding phenols, those of the MBAs decay predominantly by fragmentation of the benzene ring, yielding to nonidentified aliphatic products. The replacement of -OCH3 by -OH is practically not influenced by the presence of oxygen, it increases in the sequence 3-MBA 4-MBA 2-MBA. For 2-MBA, yields of more than 15% are obtained. Both processes, hydroxylation as well as demethoxylation, might be of importance for the recognition of radiolytical changes in foodstuff.
- Gaisberger,Solar
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- A dual-phase oscillatory behavior in Belousov Zhabotinsky system with vanillin as the substrate
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Dual-phase oscillations are observed in Belousov-Zhabotinsky system with 4-hydroxy-3-methoxybenzaldehyde (vanillin) as the substrate and manganous sulphate or ammonium Ce(IV) sulphate as the catalyst. The nonoscillatory period of time between the two phases decreases with increase in the concentration of the catalyst and the substrate. Under uncatalyzed and ferroin catalyzed conditions the system exhibits single-phase oscillations. The first-phase oscillations are due to vanillin whereas the second-phase oscillations are brought about by 4-hydroxy-3-methoxybenzoic acid (vanillic acid) formed during the course of the first-phase reactions. The reactions are explained with relevant steps of the FKN mech- anism. 1998 lohn Wiley & Sons, Inc.
- Sridevi,Ramaswamy
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- CYP199A4 catalyses the efficient demethylation and demethenylation of para-substituted benzoic acid derivatives
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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.
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- Oxidation of vanillin by diperiodatocuprate(III) in aqueous alkaline medium: A kinetic and mechanistic study by stopped flow technique
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The kinetics of oxidation of vanillin (VAN) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.50 mol dm -3 was studied spectrophotometrically. The reaction between DPC and vanillin in alkaline medium exhibits 1:2 stoichiometry (vanillin: DPC). The reaction is of first order in [DPC] and has less than unit order in both [VAN] and [alkali]. Intervention of free radicals was observed in the reaction. Increase in periodate concentration decreases the rate. The oxidation reaction in alkaline medium has been shown to proceed via a monoperiodatocuprate(III)- vanillin complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main products were identified by spot test, IR, and MS studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined.
- Hiremath,Kiran,Nandibewoor
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- ESTERS FROM Ferula stylosa
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From the total extractive substances of the roots of Ferula stylosa two esters have been isolated: chimganin and a new one - stylosin.The structure of stylosin is suggested as the ester of 4-hydroxy-3-methoxybenzoic acid and the monoterpene alcohol fenchol.
- Bagirov, V. Yu.,Sheichenko, V. I.,Aliev, G. V.,Pimenov, M. G.
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- C-glucosyl flavones from the seeds of ziziphus jujuba var. spinosa
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A new C-glucosyl flavone, 6'-vanilloylspinosin (1), was isolated from the seeds of Ziziphus jujuba var. spinosa, together with three known C-glucosyl flavones, spinosin (2), 6'-feruloylspinosin (3), and isospinosin (4). The structure of 1 was elucidated by spectral methods (1D NMR, ESI-MS, HR-MS, 2D NMR).
- Wu, Yi,He, Feng,Pan, Qin,Shi, Yao,Min, Zhida,Liang, Jingyu
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- Reactivity in the Para Oxo Ketene Route of Ester Hydrolysis. The Effect of Internal Nucleophilicity and the Irrelevance of B Strain
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The hydrolysis of 2,4-dinitrophenyl (DNP) esters of substituted 4-hydroxybenzoic acids obeys the equation kobsd = (ka + kb->)/(1 + +>/Ka) and involves a para oxo ketene intermediate.The ka term fits a Broensted equation against the pK of the 4-hydroxybenzoate (log ka = 1.15pKa - 11.71) provided the 2,6-positions of the benzoate are free.The ka term for the 2,6-dimethyl-4-hydroxybenzoate ester is 1015-fold larger than that for the parent 4-hydroxybenzoate ester.An electronic effect due to different hydroxyl pKa's may be calculated from the above linear free energy relationship to contribute 1.6percent of the discrepancy.The other component of the discrepancy is ascribed to a preferred alignment of the ester in the 2,6-dimethyl case perpendicular to the plane of the aromatic ring. The fused ketene in the microscopic reverse reaction has a LUMO acceptor orbital perpendicular to the plane of the ring, in agreement with our conclusions.Force-field calculations of nonbonding interactions indicate no strain release in the elimination mechanism giving rise to ka.The dramatic (107-fold) enhancement of the apparent second-order rate constant for alkaline hydrolysis of the 2,6-dimethyl ester compared with that of the corresponding 2',4'-dinitrophenyl 4-methoxy-2,6-dimethylbenzoate is due mostly to the steric strain imposed in the tetrahedral transition state for the latter reaction.This strain is not sufficient, however, to cause the normal BAc2 mechanism in the alkaline hydrolysis of mesitoates to change to a "square planar" concerted process.
- Thea, Sergio,Cevasco, Giorgio,Guanti, Giuseppe,Kashefi-Naini, Nasrin,Willams, Andrew
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- STRUCTURES OF FERSIN AND FERSININ
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Two new compounds - fersin and fersinin - have been isolated from the neutral fraction of the total extractive substances from the roots of Ferula soongorica.Their structures have been established on the basis of chemical transformations and spectral characteristics.
- Nazhimitdinova, N. N.,Saidkodzhaev, A. I.,Malikov, V. M.
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- ISOFLAVONES OF TWO IRIS SPECIES
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Analysis of the methanol extracts of the rhizomes of Iris milesii resulted in the isolation of a new isoflavone, 5,6,7,4'-tetrahydroxy-3'-methoxyisoflavone and that of Iris kumaonensis, iriskumaonin methyl ether, iriskumaonin, irisflorentin, junipegenin-A, irigenin and iridin.Key Word Index - Iris milesii; Iris kumaonensis; Iridaceae; rhizomes; isoflavones.
- Agarwal, W. K.,Thappa, R. K.,Agarwal, S. G.,Mehra, M. S.,Dhar, K. L.
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- Hydroxybenzoic acids from Boreava orientalis
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A new guaiacylglycerol ether, threo-guaiacylglycerol-8'-vanillic acid ether, pyrocatechuic acid, pyrocatechuic acid 3-O-β-D-glucoside, gentisic acid, gentisic acid 5-O-β-D-glucoside, vanillic acid and vanillic acid 4-O-β-D-glucoside were identified from fruits of Boreava orientalis.Structural elucidation was carried out on the basis of UV, mass, 1H and 13C NMR spectral data, including 2D shift-correlation and selective INEPT experiments.
- Sakushima, Akiyo,Coskun, Maksut,Maoka, Takashi
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- Synthesis and characterization of biobased polyesters derived from vanillin-based schiff base and cinnamic acid derivatives
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Renewable resources-based homo- and copolyesters were prepared from novel vanillin-based Schiff base and biobased cinnamic acid derivatives by transesterification. Chemical structures of the Schiff base and resulting polyesters were confirmed by FT-IR, 1HNMR, and 13CNMR. Glass-transition temperatures of polymers were determined by DSC and showed over 100 °C. Photoluminescence properties were investigated for the Schiff base and polyesters. For polymers, broader emission spectra were observed compared with monomers, which probably originated from intramolecular charge transfer in each monomeric unit.
- Sun, Hong,Kanehashi, Shinji,Tsuchiya, Kousuke,Ogino, Kenji
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- Dianthosaponins G–I, triterpene saponins, an anthranilic acid amide glucoside and a flavonoid glycoside from the aerial parts of Dianthus japonicus and their cytotoxicity
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Extensive isolation work on the 1-BuOH-soluble fraction of a MeOH extract of the aerial parts of Dianthus japonicus afforded three further triterpene glycosyl estsers, termed dianthosaponins G–I, an anthranilic acid amide glucoside and a C-glycosyl flavonoid along with one known triterpene saponin. Their structures were elucidated from spectroscopic evidence. The cytotoxicity of the isolated compounds toward A549 cells was evaluated.
- Kanehira, Yuka,Kawakami, Susumu,Sugimoto, Sachiko,Matsunami, Katsuyoshi,Otsuka, Hideaki
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- Crystal Structure and Regiospecificity of Catechol O-Methyltransferase from Niastella koreensis
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Catechol O-methyltransferase (COMT) is an enzyme that transfers a methyl group to the catechol-derivative substrates using S-adenosyl-l-methionine (SAM) and Mg2+. We report the biochemical and structural analysis of COMT from Niastella koreensis (NkCOMT). NkCOMT showed the highest activity with Mg2+, although the enzyme also showed a significant level of activity with Cu2+ and Zn2+. NkCOMT structures complexed with SAH and Mg2+ elucidated how the enzyme stabilized the cosubstrate and the metal ion and revealed that the region near the SAM binding site undergoes conformational changes upon the binding of the cosubstrate and the metal ion. We also identified the catechol binding pocket of the enzyme and explained a broad substrate specificity of the bacterial enzyme and its ability to accommodate the catechol derivatives. In addition, we developed the NkCOMTE211R and NkCOMTE211K variants that showed both enhanced activities and regiospecificity for the production of the para-forms. Our study provides a structural basis for regiospecificity of NkCOMT, which is related with the conformational change upon binding of SAM and Mg2+.
- Lee, Seul Hoo,Kim, Bongsang,Kim, Kyung-Jin
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- Synthesis of Lignin-based Phenol Terminated Hyperbranched Polymer
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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
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- Mechanistic Investigations of Uncatalyzed and Ruthenium(III) Catalyzed Oxidation of Vanillin by Periodate in Aqueous Alkaline Medium
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Abstract The kinetics and mechanism of uncatalyzed and ruthenium(III) catalyzed oxidation of vanillin (Van) by periodate were studied in alkaline medium at 298 K, and at constant ionic strength of 0.3 mol·dm-3. The reaction exhibits 1:1 stoichiometry ([Van]:[periodate]). The reaction shows first-order kinetics in [periodate] and [Ru(III)] and less than unit order with respect to [Van] and [OH-]. The ionic strength and dielectric constant of the medium did not affect the rate significantly. The main products were identified by spot tests, melting temperature and FT-IR. From the effect of temperature on the reaction rate, the Arrhenius and activation parameters have been calculated. The catalytic constant (K C) was also calculated for Ru(III) catalysis at different temperatures. Plausible mechanisms have been proposed and rate laws explaining the experimental results are derived. Kinetic studies suggest that the active species of periodate and Ru(III) were [H2IO6]3- and [Ru(H2O)5OH]2+, respectively. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to the slow step of the mechanism, along with the corresponding thermodynamic quantities, were determined and discussed.
- Patil, Deepa G.,Magdum, Prashant A.,Nandibewoor, Sharanappa T.
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- Total synthesis of triazole-linked C-glycosyl flavonoids in alternative solvents and environmental assessment in terms of reaction, workup and purification
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An efficient total synthesis of triazole-linked C-glycosyl flavonoids was developed without the use of protective groups in order to promote atom economy, employing alternative solvents, and choosing the least toxic reagents. Aiming to measure the impact of the operation that affects the mass intensity to a greater extent, we envisaged first determining this green metric for the reaction (MIR), the workup (MIW), and the purification (MIP) for each step and then taking advantage of these values to calculate the contributions to the total synthesis.
- Pessel, Freddy,Billault, Isabelle,Scherrmann, Marie-Christine
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- Kinetics and mechanism of the oxidation of vanillin by hexacyanoferrate(III) in aqueous alkaline medium
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The title reaction was investigated in aqueous alkaline medium. A first-order dependence in hexacyanoferrate(III) concentration and a fractional order in both vanillin and alkali were obtained at the concentrations studied. The added product, hexacyanoferrate(II), had a retarding effect on the rate of reaction. Ionic strength and dielectric constant of the reaction medium have little effect on the reaction rate. The effect of temperature on the rate of reaction has also been studied and activation parameters have been evaluated. A mechanism based on the experimental results is proposed and the rate law is derived. The reaction constants are calculated and used to regenerate the k obs values, which are compared with the experimental values.
- Jose, Timy P.,Nandibewoor, Sharanappa T.,Tuwar, Suresh M.
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- Multi-Enzymatic Cascade Reactions for the Synthesis of cis,cis-Muconic Acid
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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
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p. 114 - 123
(2021/10/07)
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- Oxidative cleavage of C-C double bond in cinnamic acids with hydrogen peroxide catalysed by vanadium(v) oxide
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We have developed a cheap, green, mild and environmentally friendly method for the selective cleavage of carbon-carbon double bonds with a 30% aqueous solution of hydrogen peroxide as the oxidant and vanadium(v) oxide as the catalyst. The selectivity of the oxidative cleavage of cinnamic acid derivatives 1 depends on the substituents and the solvent used (DME - MeOCH2CH2OMe, TFE - 2,2,2-trifluoroethanol or MeCN). In DME, p-hydroxy derivatives were selectively converted to benzaldehyde derivatives 2, in TFE, oxidative cleavage led to the formation of benzoquinone derivatives 4, while in MeCN, cinnamic acid derivatives were selectively converted to benzoic acid derivatives 3. Ferulic acid 1a was quantitatively and selectively converted to vanillin 2a in a 91% isolated yield on a gram scale. Dimeric difurandione 1a′ was isolated as an intermediate, which was confirmed by in situ ATR-IR spectroscopy, while the formation of diols or epoxides was not observed. The analogous styrene derivative, 4-vinylguaiacol 1e was also selectively converted to either vanillin 2a or 2-methoxyquinone 4a in a high yield. The green metric for the conversion of ferulic acid to vanillin by different methods was calculated and compared to our method, and showed that our method has better environmental parameters.
- Horvat, Monika,Iskra, Jernej
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p. 2073 - 2081
(2022/04/07)
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- Correlation studies in the oxidation of Vanillin Schiff bases by acid bromate - A kinetic and semi-empirical approach
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Kinetics and mechanistic aspects of oxidation of Vanillin Schiff bases (obtained from Vanillin and p-substituted anilines) by bromate in acid medium has been studied at 313 ?K. The reaction exhibited first order in [bromate] and less than unity order each in [Vanillin Schiff base] and [acid]. The increase in the rate of reaction with decrease in dielectric constant of the medium is observed with all the studied substrates. The reaction failed to induce the polymerization of acrylonitrile. Electron withdrawing substituents in the aniline ring moiety of Vanillin Schiff base accelerate the rate of oxidation to a large extent and electron releasing substituents retard the rate. The order of reactivity is found to be p-nitro ?> ?p-bromo ?> ?p-chloro ?> ?–H ?> ?p-fluoro ?> ?p-methyl ?> ?p-methoxy ?> ?p-ethoxy and the sensitivity of the substrates towards the reaction rate is further supported by the semi-empirical calculation of electronic properties and global descriptors of the substrates (Vanillin Schiff bases) with different substituents in the aniline ring moiety. The observed trend in the reactivity of the substrates was correlated with the calculated descriptors like electronegativity, chemical potential, electrophilicity index, chemical hardness and frontier molecular orbitals. The linear free-energy relationship is characterized by a straight line in the Hammett's plot of log k versus σ. The ρ values are positive and increase with increase in temperature. From the Exner and Arrhenius plots, the isokinetic relationship is discussed. Oxidation products identified are p-substituted azobenzene and vanillic acid. Based on the experimental observations, a plausible mechanism is proposed and rate law is derived.
- Sathish,Teja, P. Ravi,Ramudu, M. Parusha,Manjari, P. Sunitha,Rao, R. Koteshwar
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- An efficient environmentally friendly CuFe2O4/SiO2catalyst for vanillyl mandelic acid oxidation in water under atmospheric pressure and a mechanism study
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With the aim of the green production of vanillin, a highly efficient environmentally friendly oxidation system was introduced to oxidize vanillyl mandelic acid (VMA) with a porous CuFe2O4/SiO2 component nano-catalyst in aqueous solution under atmospheric pressure. The N2 adsorption-desorption pattern indicated that CuFe2O4/SiO2 possessed a much higher specific surface area (49.98 m2 g-1) than that of CuFe2O4 (5.02 m2 g-1), which further indicated that the SiO2 substrate restrained the aggregation of CuFe2O4 nanoparticles. The conversion for VMA and selectivity for vanillin reached 98% and 96%, respectively, under atmospheric pressure. The excellent catalytic performance was attributed to the synergistic effect of the catalytic capacity of CuFe2O4 and the adsorption capacity for the reactant of SiO2. Simultaneously, the effect of different reaction conditions for catalyst activity and selectivity were investigated. Furthermore, the probable mechanism of VMA oxidation was investigated by in situ ATR-FTIR, H2-TPR, XPS and 1H NMR. More importantly, the decarboxylation was verified to proceed in basic conditions rather than in conventional acidic conditions. This journal is
- Mao, Haifang,Wang, Hongzhao,Meng, Tao,Wang, Chaoyang,Hu, Xiaojun,Xiao, Zuobing,Liu, Jibo
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p. 982 - 992
(2021/01/25)
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- A chlorogenic acid esterase from a metagenomic library with unique substrate specificity and its application in caffeic and ferulic acid production from agricultural byproducts
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Soil microbes are an abundant source of enzymes with unique properties that may be useful for industrial applications. As most wild-type strains show low chlorogenic acid esterase expression and activity, and most microbes cannot be cultured in the laboratory, a metagenomic approach provides methods of identifying new enzymes. In this study, a gene encoding a chlorogenic acid esterase, named Tan410, was isolated from a soil metagenomic library and overexpressed in Escherichia coli BL21 (DE3). The recombinant enzyme, with a predicted molecular weight of 54.88 kDa, was purified to homogeneity. The K m and V max values for Tan410 were 1.26 mM and 0.33 mM min–1, respectively, with chlorogenic acid as the substrate. Its optimum temperature and pH for reaction were 30 °C and 7.5, respectively. The enzyme exhibited moderate thermostability and broad pH stability (3.0–10.0). Tan410 was also able to hydrolyse ethyl ferulate, methyl caffeate, propyl gallate, ethyl gallate, methyl vanillate, methyl benzoate, ethyl benzoate, methyl 2,5-dihydroxybenzoate, and methyl 3,5-dihydroxybenzoate, and it released caffeic and ferulic acids from agricultural byproducts (destarched wheat bran and coffee pulp). Tan140 has potential for industrial application in biomass valorization.
- Gui, Lun,Long, Qizhang,Yao, Jian
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- Method for industrially producing protocatechuic acid
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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; 0035; 0037; 0038; 0040; 0041
(2020/07/15)
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- Highly efficient oxidation of alcohols to carboxylic acids using a polyoxometalate-supported chromium(iii) catalyst and CO2
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Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes.
- Han, Sheng,Wang, Ying,Wei, Yongge,Wu, Zhikang,Yu, Han
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p. 3150 - 3154
(2020/06/19)
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- Regioselectivity of Cobalamin-Dependent Methyltransferase Can Be Tuned by Reaction Conditions and Substrate
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Regioselective reactions represent a significant challenge for organic chemistry. Here the regioselective methylation of a single hydroxy group of 4-substituted catechols was investigated employing the cobalamin-dependent methyltransferase from Desulfitobacterium hafniense. Catechols substituted in position four were methylated either in meta- or para-position to the substituent depending whether the substituent was polar or apolar. While the biocatalytic cobalamin dependent methylation was meta-selective with 4-substituted catechols bearing hydrophilic groups, it was para-selective for hydrophobic substituents. Furthermore, the presence of water miscible co-solvents had a clear improving influence, whereby THF turned out to enable the formation of a single regioisomer in selected cases. Finally, it was found that also the pH led to an enhancement of regioselectivity for the cases investigated.
- Pompei, Simona,Grimm, Christopher,Farnberger, Judith E.,Schober, Lukas,Kroutil, Wolfgang
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p. 5977 - 5983
(2020/10/06)
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- Mechanochemical cleavage of lignin models and ligninviaoxidation and a subsequent base-catalyzed strategy
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Mechanochemical cleavage of lignin dimer model compounds to phenolic monomers has been developedviaa two-step strategy under milling conditions. In the first step of this process, the secondary benzylic alcohol of lignin β-O-4 linkages was selectively oxidized to the corresponding ketones over a 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)/NaNO2catalytic system under milling conditions. In the subsequent step, mechanochemical selective cleavage of the Cβ-O bonds and Cα-Cβbonds of lignin β-O-4 ketones to acids and phenols was promoted by NaOH-catalyzed depolymerization. In addition, this two-step strategy was performed to depolymerize organosolv birch lignin, giving aromatic monomers with good selectivity for syringate. This approach provides an efficient method to convert the β-O-4 linkages of lignin to valuable aromatic monomers under mild reaction conditions.
- Dushkin, Alexandr V.,Su, Weike,Sun, Chen,Xu, Wenhao,Zheng, Lei
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supporting information
p. 3489 - 3494
(2020/07/30)
-
- Selective production of bio-based aromatics by aerobic oxidation of native soft wood lignin in tetrabutylammonium hydroxide
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Aerobic oxidation of native soft wood lignin in an aqueous solution of Bu4NOH facilitates efficient production of vanillin (4-hydroxy-3-methoxybenzaldehyde), which is one of the platform chemicals in industry. Oxidation of Japanese cedar (Cryptomeria japonica) wood flour at 120 °C for 4 h under O2in Bu4NOH-based aqueous solutions produced vanillin in 23.2 wt% yield based on the Klason lignin content of the starting material. This yield was comparable to that in alkaline nitrobenzene oxidation of the same material (27.2%), which indicated that our aerobic oxidation exploited the full potential of the wood flour for vanillin production. Further mechanical investigation with lignin model compounds suggested that the vanillin formation occurred mainly through following successive reactions: alkaline-catalyzed degradation of ?-ether linkages in middle units of lignin polymer to form a glycerol end group, oxidation of the glycerol end group by O2to a HCa?O moiety, and release of vanillin from the HCa?O end. One of the reasons for the high performance of Bu4NOH for the vanillin production was explained by the general understanding in organic chemistry that Bu4OH is a stronger base than simple alkali,e.g.NaOH. The other more fundamental mechanical aspect was that Bu4N+suppressed disproportionation of the vanillin precursor (the CaHO end group) probably due to strong interaction between the cation and the HCa?O end group.
- Hosoya, Takashi,Miyafuji, Hisashi,Yamada, Tatsuhiko,Yamamoto, Kohei
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p. 19199 - 19210
(2020/06/04)
-
- Directly Microwave-Accelerated Cleavage of C?C and C?O Bonds of Lignin by Copper Oxide and H2O2
-
Model erythro, phenolic, and nonphenolic lignin β-O-4 dimer compounds are treated with copper oxide and H2O2 at the electronic field maximum position of a single-mode 2.45 GHz microwave system equipped with a cavity resonator. The products obtained through microwave heating and oil-bath heating with the same reaction vessel and temperature profile are quantitatively compared. Dimer degradation is found to proceed through consecutive elementary reactions. The phenolic dimer is dehydroxylated and this is followed by the spontaneous cleavage of Cα?Cβ and C?O?C bonds to produce guaiacol, vanillin, and vanillic acid. The reaction of the nonphenolic dimer produces veratric acid, veratraldehyde, and guaiacol. Microwave irradiation accelerates cleavage of the side chain and the oxidation of vanillin to vanillic acid. However, no acceleration of veratraldehyde oxidation to veratric acid or aromatic ring cleavage to produce dicarboxylic acids is observed. The selective acceleration of elementary reactions during the degradation of model lignin compounds indicates that microwaves interact with reaction intermediates that are sensitive to electromagnetic waves.
- Qu, Chen,Ito, Keigo,Katsuyama, Isamu,Mitani, Tomohiko,Kashimura, Keiichiro,Watanabe, Takashi
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p. 4510 - 4518
(2020/05/18)
-
- Acylated iridoid glycosides with hyaluronidase inhibitory activity from the rhizomes of Picrorhiza kurroa Royle ex Benth
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Seven new acylated iridoid glycosides, picrorhizaosides A–G (1–7), were isolated from the methanol extract of the rhizomes of Picrorhiza kurroa Royle ex Benth. (Plantaginaceae), in addition to six known iridoid glycosides (8–13). The structures of these new iridoids, including their stereochemistry, were determined based on chemical and physicochemical evidence derived from NMR and MS analysis. Of the isolates, picrorhizaosides D (4, IC50 = 43.4 μM) and E (5, 35.8 μM); picrosides I (8, 60.7 μM), II (9, 22.3 μM), and IV (11, 59.2 μM); and minecoside (13, 57.2 μM), exhibited a similar or stronger hyaluronidase inhibitory activity than those of the antiallergic medicines disodium cromoglycate (64.8 μM), ketotifen fumarate (76.5 μM), and tranilast (227 μM).
- Morikawa, Toshio,Nakanishi, Yusuke,Inoue, Naoki,Manse, Yoshiaki,Matsuura, Hideyuki,Hamasaki, Shinya,Yoshikawa, Masayuki,Muraoka, Osamu,Ninomiya, Kiyofumi
-
-
- Microbial conversion of vanillin from ferulic acid extracted from raw coir pith
-
Coir pith, an agro-industrial residue, is resistant to natural degradation, and its accumulation causes environmental pollution. Ferulic acid, a precursor of vanillin, was extracted from the raw coir pith by chemical pre-treatment such as alkaline hydrolysis, acidification, and liquid–liquid extraction method. The obtained ferulic acid (1.2 g/50 g) was analysed using high-performance liquid chromatography (HPLC) and used as a substrate for biotransformation by Aspergillus niger to vanillic acid, which, in turn, was fermented by using Phanerochaete chrysosporium to vanillin. The quantity of vanillic acid detected by HPLC on the third day of incubation was 0.773 g/L, while the optimal yield of vanillin on the subsequent third day of incubation was 0.628 g/L. Thus, the chemical extraction of ferulic acid from coir pith ensued bioconversion into vanillin. These products are highly valuable and economical to be used in industries such as pharmaceuticals, health, cosmetics, and neutraceuticals.
- Radhakrishnan, Sivaramapillai,Rejani, Chalikkaran Thilakan
-
-
- Effective Control of Particle Size and Electron Density of Pd/C and Sn-Pd/C Nanocatalysts for Vanillin Production via Base-Free Oxidation
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The effective control of particle size and electron density of metal active sites is challenging yet important for supported nanoparticles, as size effects and promoter effects play vital roles in heterogeneous catalysis on the nanoscale. In this work, we report Pd/C and Sn-Pd/C nanocatalysts for the base-free aerobic oxidation of vanillyl alcohol to vanillin, a challenging reaction not only in the fundamental research of selective oxidation of alcohols but also for the practical transformation of bio-based alcohols to value-added chemicals. We effectively tuned the mean size of Pd nanoparticles from 1.8 to 6.7 nm by varying the temperature used for catalyst preparation and further modified the electron density of the Pd/C catalyst by adding a SnO2 promoter with different loadings. TEM, HAADF-STEM, XPS, CO chemisorption, and in situ DRIFT-IR of CO adsorption characterizations allowed us to get insight into the unique catalytic properties of Pd nanocatalysts. It was conjectured that the base-free aerobic oxidation of vanillyl alcohol to vanillin over the Pd/C catalyst can be a structure-sensitive reaction and the Pd particle size was decisive for the dispersion of Pd, the proportion of catalytically active Pd0 sites, and the intrinsic turnover frequency (iTOF). The 1 wt % Pd/C (1.8 nm) catalyst showed an iTOF value of 268 h-1 and 100% yield to vanillin at 120 °C, 5 bar of O2, and 20 mg of the catalyst within 9 h. We further demonstrated that Sn4+ ions in SnO2 as an electronic promoter can promote Pd/C activity by the formation of highly active, electron-sufficient Pd0 sites which significantly lowered the apparent activation energy of reaction. The 0.1Sn-Pd/C catalyst showed a higher iTOF value of 458 h-1 and a yield of 100% to vanillin at 120 °C, 3 bar of O2 and 15 mg of the catalyst within 6 h. Moreover, we verified a satisfying reusability and an adequate substrate scope over the 0.1Sn-Pd/C catalyst.
- Cao, Qiue,Fang, Wenhao,Lu, Yaowei,Sun, Weixiao,Wang, Yongxing,Wu, Shipeng
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p. 7699 - 7709
(2020/08/21)
-
- Mpsc6 binuclear complexes immobilized on graphene oxide for oxidation of lignin model compounds and lignin
-
An efficient process for the oxidative degradation of lignin using M-GO (MPSC6 binuclear complexes immobilized on graphene oxide) biomimetic catalysts in acetonitrile was developed in this work. Different M-GO catalysts (M=Co, Cu, Zn and Ni) were used to catalyze the depolymerization of lignin model compounds and organosolv lignin. The results showed that the immobilization of MPSC6 complexes on GO was favorable for regulating the valuable depolymerization of the model compounds and lignin. The optimal solid catalyst Co-GO exhibited high catalytic activity, which showed a 83.04% conversion of phenolic β-O-4 lignin model compound, a 91.26% conversion of veratryl alcohol and a 96.24% conversion of vanillyl alcohol with a catalyst/model compound ratio of 50 mg:10 mmol and a dosage of 15 mmol H2O2 at 80 °C for 3 h. The stuctural changes of organosolv lignin occurred in catalytic oxidation were analyzed in terms of O/C ratio, molecular weight and OH content of lignin samples, and a plausible mechanism involving the formation of aromatic products and muconolactone from lignin depolymerization over M-GO was also proposed.
- Yang, Xiao-Jun,Zhou, Xue-Fei,Zou, Zheng-Rong
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p. 973 - 982
(2021/06/26)
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- Specific Residues Expand the Substrate Scope and Enhance the Regioselectivity of a Plant O-Methyltransferase
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An isoeugenol 4-O-methyltransferase (IeOMT), isolated from the plant Clarkia breweri, can be engineered to a caffeic acid 3-O-methyltransferase (CaOMT) by replacing three consecutive residues. Here we further investigated functions of these residues by constructing the triple mutant T133M/A134N/T135Q as well as single mutants of each residue. Phenolics with different chain lengths and different functional groups were investigated. The variant T133M improves the enzymatic activities against all tested substrates by providing beneficial interactions to residues which directly interact with the substrate. Mutant A134N significantly enhanced the regioselectivity. It is meta-selective or even specific against most of the tested substrates but para-specific towards 3,4-dihydroxybenzoic acid. The triple mutant T133M/A134N/T135Q benefits from these two mutations, which not only expand the substrate scope but also enhance the regioselectivity of IeOMT. On the basis of our work, regiospecific methylated phenolics can be produced in high purity by different IeOMT variants.
- Tang, Qingyun,Bornscheuer, Uwe T.,Pavlidis, Ioannis V.
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p. 3227 - 3233
(2019/07/04)
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- PROCESS FOR PRODUCTION OF CARBOXYLATED PHENOL DERIVATIVES
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Disclosed is a new process for the production of carboxylated phenol derivatives comprising at least a step of carboxylation of a mixture of (i) phenol derivative and (ii) phenolate derivative, wherein the molar ratio of (i) / (ii) is comprised between 0.8 and 1.2, in presence of CO2. A process for the production of said mixture of (i) phenol derivative and (ii) phenolate derivative is also disclosed.
- -
-
Page/Page column 11-13
(2019/02/25)
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- Comprehensive kinetic and substrate specificity analysis of an arylsulfatase from Helix pomatia using mass spectrometry
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Sulfatases hydrolyze sulfated metabolites to their corresponding alcohols and are present in all domains of life. These enzymes have found major application in metabolic investigation of drugs, doping control analysis and recently in metabolomics. Interest in sulfatases has increased due to a link between metabolic processes involving sulfated metabolites and pathophysiological conditions in humans. Herein, we present the first comprehensive substrate specificity and kinetic analysis of the most commonly used arylsulfatase extracted from the snail Helix pomatia. In the past, this enzyme has been used in the form of a crude mixture of enzymes, however, recently we have purified this sulfatase for a new application in metabolomics-driven discovery of sulfated metabolites. To evaluate the substrate specificity of this promiscuous sulfatase, we have synthesized a series of new sulfated metabolites of diverse structure and employed a mass spectrometric assay for kinetic substrate hydrolysis evaluation. Our analysis of the purified enzyme revealed that the sulfatase has a strong preference for metabolites with a bi- or tricyclic aromatic scaffold and to a lesser extent for monocyclic aromatic phenols. This metabolite library and mass spectrometric method can be applied for the characterization of other sulfatases from humans and gut microbiota to investigate their involvement in disease development.
- Correia, Mário S.P.,Ballet, Caroline,Meistermann, Hannes,Conway, Louis P.,Globisch, Daniel
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p. 955 - 962
(2019/02/09)
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- Transition-metal-free conversion of lignin model compounds to high-value aromatics: Scope and chemoselectivity
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An efficient and straightforward reaction protocol for the conversion of lignin model compounds was developed based on a simple system consisting of a base, oxygen, and a green solvent under mild conditions in the absence of metals. This protocol was successfully applied to the cleavage of both 'β-O-4' dimeric and trimeric compounds, and a controlled selective degradation was achieved depending on the bond type. The feasibility of this method to provide aromatic compounds in high yields from lignin by a sequential oxidative dehomologation reaction was clearly demonstrated.
- Lee, Tae Woo,Yang, Jung Woon
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p. 3761 - 3771
(2018/08/21)
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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supporting information
p. 3931 - 3943
(2018/09/11)
-
- FLAME-RETARDANT VANILLIN-DERIVED SMALL MOLECULES
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A flame-retardant vanillin-derived small molecule, a process for forming a flame-retardant polymer, and an article of manufacture comprising a material that contains the flame-retardant vanillin-derived small molecule are disclosed. The flame-retardant vanillin-derived small molecule can be synthesized from vanillin obtained from a bio-based source, and can have at least one phosphoryl or phosphonyl moiety with phenyl, allyl, or thioether substituents. The process for forming the flame-retardant polymer can include reacting a diol vanillin derivative and a flame-retardant phosphorus-based molecule to form the flame-retardant vanillin-derived small molecule, and binding the flame-retardant vanillin-derived small molecule to a polymer. The material in the article of manufacture can be flame-retardant, and contain the flame-retardant vanillin-derived small molecules. Examples of materials that can be in the article of manufacture can include resins, plastics, adhesives, polymers, etc.
- -
-
Paragraph 0005
(2018/11/24)
-
- FLAME-RETARDANT VANILLIN-DERIVED MONOMERS
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A flame-retardant vanillin-derived monomer, a process for forming a flame-retardant polymer, and an article of manufacture comprising a material that contains flame-retardant vanillin-derived monomer are disclosed. The flame-retardant vanillin-derived monomer can be synthesized from vanillin obtained from a bio-based source, and can have at least one phosphoryl or phosphonyl moiety with phenyl, allyl, epoxide, or propylene carbonate substituents. The process for forming the flame-retardant polymer can include reacting a vanillin derivative and a flame-retardant phosphorus-based molecule to form the flame-retardant vanillin-derived monomer, and then polymerizing the flame-retardant vanillin-derived monomer. The material in the article of manufacture can be flame-retardant, and contain the flame-retardant vanillin-derived monomer. Examples of materials that can be in the article of manufacture can include resins, plastics, adhesives, polymers, etc.
- -
-
Paragraph 0036
(2018/11/26)
-
- Sphingobacterium sp. T2 Manganese Superoxide Dismutase Catalyzes the Oxidative Demethylation of Polymeric Lignin via Generation of Hydroxyl Radical
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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.
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p. 2920 - 2929
(2018/10/20)
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- Electrochemical Lignin Degradation in Ionic Liquids on Ternary Mixed Metal Electrodes
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Lignin is the second most abundant natural polymer and a promissing feedstock for the generation of renewable aromatic chemicals. We present an fundamental approach for the electrocatalytic cleavage of lignin dissolved in a recoverable, inexpensive ionic liquid using mixed metal oxide electrodes of different compositions. The distribution of depolymerization products generated by electrochemical oxidation were analyzed by means of mass spectrometry. The distribution and yield of the cracked species was found to depended strongly on the implemented metal catalyst and therefore offers the potential to tailor the amount and composition of the low molecular weight cleavage products. This approach could help to provide a more sustainable valorization of lignin for the potential production of high value aromatic compounds due to synergistic effects.
- Rauber, Daniel,Dier, Tobias K.F.,Volmer, Dietrich A.,Hempelmann, Rolf
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p. 189 - 208
(2017/12/18)
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- NOVEL MANUFACTURING METHOD OF LOW MOLECULAR COMPOUND FROM LIGNIN
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PROBLEM TO BE SOLVED: To provide a manufacturing method of dehydro divanillic acid dialkyl ester using lignin contained in a needle-leaves trees or the like as a raw material. SOLUTION: The manufacturing method of dehydro divanillic acid dialkyl ester through following process 1 to process 5 with using lignin as a raw material. Process 1: a process for conducting an oxidation reaction on the lignin. Process 2: a process for purifying a reaction product obtained in the process 1. Process 3: a process for conducting the oxidation reaction on a component obtained in the process 2. Process 4: a process for conducting an esterification reaction on a reaction product of the process 3 and alcohol. Process 5: a process for conducting a coupling reaction (dimerization reaction) on a reaction product in the process 4. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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-
Paragraph 0056; 0057
(2018/02/10)
-
- Catalytic Alkylation Using a Cyclic S-Adenosylmethionine Regeneration System
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S-Adenosylmethionine-dependent methyltransferases are versatile tools for the specific alkylation of many compounds, such as pharmaceuticals, but their biocatalytic application is severely limited owing to the lack of a cofactor regeneration system. We report a biomimetic, polyphosphate-based, cyclic cascade for methyltransferases. In addition to the substrate to be methylated, only methionine and polyphosphate have to be added in stoichiometric amounts. The system acts catalytically with respect to the cofactor precursor adenosine in methylation and ethylation reactions of selected substrates, as shown by HPLC analysis. Furthermore, 1H and 13C NMR measurements were performed to unequivocally identify methionine as the methyl donor and to gain insight into the selectivity of the reactions. This system constitutes a vital stage in the development of economical and environmentally friendly applications of methyltransferases.
- Mordhorst, Silja,Siegrist, Jutta,Müller, Michael,Richter, Michael,Andexer, Jennifer N.
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supporting information
p. 4037 - 4041
(2017/03/27)
-
- Tuning the photocatalytic activity of bismuth wolframate: Towards selective oxidations for the biorefinery driven by solar-light
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The sol-gel entrapment of nanostructured Bi2WO6 enhances the activity and the selectivity of the short-gap semiconductor in the sunlight-driven photo-oxidation of trans-ferulic and trans-cinnamic acid dissolved in water with air as the primary oxidant. Valuable products such as vanillin, benzaldehyde, benzoic acid and vanillic acid are obtained. This provides the proof of concept that photocatalysis could be a promising technology in tomorrow's solar biorefineries.
- Ciriminna, Rosaria,Delisi, Riccardo,Parrino, Francesco,Palmisano, Leonardo,Pagliaro, Mario
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supporting information
p. 7521 - 7524
(2017/07/12)
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- CuZrO3 nanoparticles catalyst in aerobic oxidation of vanillyl alcohol
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A highly crystalline, mesoporous and perovskite type CuZrO3 nanoparticles catalyst was prepared via a simple and facile one pot solvent evaporation method. The crystal planes (112) and (211) of CuZrO3 were evidenced in HRTEM and SAED imagery by their lattice parameters, 2.83 and 3.15 ?. Also, the crystallite size of synthesized catalyst was measured in a range of 7-10 nm. The catalyst was superior as it possessed many physiochemical properties to perform a liquid phase aerobic oxidation of vanillyl alcohol to selectively produce vanillin under base free conditions. Catalytic activity of the synthesized perovskite type CuZrO3 catalyst was substantially improved by the presence of surface oxygen vacancies speculated in O 1s spectra. Furthermore, a O2-TPD technique was applied to understand the role of surface oxygen vacancy in enhancing catalytic activity. Moreover, numerous partial and full lattice dislocated grain boundaries were observed as a form of structural defects between different planes in HRTEM imagery. The redox capability of this superior catalyst was significantly enriched by the high content of Zr loading and confirmed by low temperature reduction in H2-TPR analysis. Excellent catalytic behavior of CuZrO3 (Cu:2Zr) catalyst (91% conversion and 76% selectivity to vanillin) in liquid phase aerobic oxidation was well correlated with the structural and chemical properties of the catalyst. Moreover, the catalyst was stable for four consecutive oxidation reactions without appreciable loss of catalytic activity.
- Saha, Subrata,Abd Hamid, Sharifah Bee
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p. 9914 - 9925
(2017/02/15)
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- Cobalt-catalyzed Aerobic Oxidation of Eugenol to Vanillin and Vanillic Acid
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A novel, simple, one-step method of synthesizing vanillin and vanillic acid from eugenol has been developed. The method uses ligand- and additive-free Co(OAc)2·4H2O as catalyst and molecular oxygen as oxidant to achieve catalytic process without isomerizing eugenol. Extensive screening efforts were used to optimize eugenol to obtain vanillin and vanillic acid. Under optimal conditions, the reaction provided vanillin and vanillic acid with 68.5% and 15.2% yields, respectively. Apart from the desired products, coniferyl alcohol 9-methyl ether and 4-hydroxy-3-methoxycinnamaldehyde as two intermediates were also detected in the reaction process. Level changes of all compounds over time were presented in the reaction. The reaction pathway from eugenol to vanillic acid was validated by conducting several control experiments. Furthermore, a possible reaction mechanism dominated by a circular redox reaction from Co(III) and Co(II) species was proposed. This method offers a potentially practical alternative for manufacturing vanillin and vanillic acid efficiently.
- Mao, Haifang,Wang, Lizhi,Zhao, Feifei,Wu, Jianxin,Huo, Haohua,Yu, Jun
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p. 261 - 266
(2016/04/19)
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- Role of alkali in catalytic oxidation of p-cresols
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The investigation of alkali acting as the key component during the liquid-phase catalytic oxidation of p-cresols to p-hydroxyl aromatic aldehydes is far from satisfied, thus a detailed exploration is presented. It was observed that the p-cresols were activated by alkali to form phenolate salt to ensure mild reaction conditions demonstrated by comparing the oxidation of p-cresol and its phenolate sodium. It was also found that excess alkali improved the selectivity of aldehyde by inhibiting the formation of dimeric side products in view of an analysis of the side products distribution. The alkaline alcoholic anion facilitates the 1,6-addition reaction between p-benzoquinone methide and solvent. Thus, more alkali was needed in solvents with high pKa values and high water content. The detection of trace acid during the oxidation of p-cresols suggested the phenoxy radical mechanism rather than the classic benzyl radical mechanism proposed for interpreting the oxidation of non-hydroxyl aromatic hydrocarbons. These conclusions contribute significantly to both the understanding of role of alkali during the reaction process and the mechanism study for the catalytic oxidation of cresols and non-hydroxyl aromatic hydrocarbons.
- Ma, Qiyi,Liang, Cheng,Chen, Kexian,Liu, Kejing,Mao, Jianyong,Chen, Zhirong,Li, Haoran
-
-
- NMR Assignment for Diaryl Ether Structures (4-O-5 Structures) in Pine Wood Lignin
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A 4-O-5-tetramer lignin model compound carrying β-O-4 linkages on each of the side-chain moieties was synthesized, as well as 4-O-5-coupled dehydrodiconiferyl alcohol. By comparison with their NMR data, two cross-signals in the HSQC spectrum of pine milled wood lignin recorded in DMSO-d6 were assigned to H2/C2 and H6/C6 correlations on the aromatic rings of 4-O-5-linked units. Although the H2/C2 correlation peak appeared in the same region as syringyl units, nitrobenzene oxidation of the pine lignin did not yield any syringyl-type product, but did release a 4-O-5-type product.
- Li, Yanding,Akiyama, Takuya,Yokoyama, Tomoya,Matsumoto, Yuji
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p. 1921 - 1929
(2016/07/06)
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- GENETIC ENGINEERING OF PSEUDOMONAS PUTIDA KT2440 FOR RAPID AND HIGH YIELD PRODUCTION OF VANILLIN FROM FERULIC ACID
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The present invention relates to an improved biocatalytic process for producing vanillin from ferulic acid based on a genetically engineered Pseudomonas strains, as well as to said Pseudemonas strains.
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-
Paragraph 0185; 0186
(2016/07/05)
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- Synthesis and characterization of di-μ-oxidovanadium(V), oxidoperoxido-vanadium(V) and polymer supported dioxidovanadium(V) complexes and catalytic oxidation of isoeugenol
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The tridentate ONN donor ligand, Hbzpy-fah (I) (Hbzpy-fah = Schiff base derived from 2-benzoylpyridine and 2-furoylhydrazide) upon reaction with [VIVO(acac)2] in methanol followed by aerial oxidation give a dinuclear complex, [{VVO(bzpy-fah)}2(μ-O)2] (1) having [{VVO}2(μ-O)2]2+ core. Treatment of 1 with H2O2 in methanol results in the formation of dinuclear peroxido complex, [{VVO(bzpy-fah)}2(μ-O2)2] (2). The molecular structure of 2 was determined by single-crystal X-ray diffraction, confirming the ONN binding mode of I and μ-bis(peroxido) with side-on coordination. Reaction of 1 with imidazolomethylpolystyrene cross-linked with 5% divinylbenzene (PS-im) in DMF gives the polymer-supported complex 3 (abbreviated as PS-im[VVO2(bzpy-fah)]) which was characterized by field-emission scanning electron micrographs (FE-SEM) as well as energy dispersive X-ray (EDAX), atomic force microscopy (AFM) and thermal analysis along with usual spectroscopic techniques. Complexes 1 and 3 have been used as catalyst precursors for the oxidation of isoeugenol in the presence of aqueous H2O2 as oxidant and gave vanillin, vanillic acid and dehydrodiisoeugenol. The polymer-supported complex showed higher conversion than its neat counterpart. This has also allowed for recyclable catalytic system with increased catalyst lifetime and thus proved to be better over the homogeneous counterpart.
- Maurya, Mannar R.,Uprety, Bhawna,Chaudhary, Nikita,Avecilla, Fernando
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p. 230 - 238
(2015/06/30)
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- Purification, characterization and in-silico analysis of nitrilase from Gordonia terrae
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An inducible and aromatic nitrilase from Gordonia terrae was purified with a yield of 19%. The enzyme had turnover number of 63 s-1 × 10-3, Km1.4 mM and Vmax95 Umg-1 protein for benzonitrile. The nitrilase of G. terrae was active at basic pH (7-10), moderate temperature (20-45 °C) and has a half-life of 4 h at 35 °C. MALDI analysis and amino acid sequence deduced from cloned nucleotide fragment showed 97% homology with putative amidohydrolase of Gordonia sputi NBRC 100414 and G. namibiensis. The enzyme showed regioselectivity towards hydroxybenzonitriles, as different position of hydroxyl group i.e. meta-, para- and orthosubstitutions on benzonitrile effect enzyme activity. The in-silico interactions of these substrates with the predicted 3D model of this enzyme also showed differential interaction between hydroxyl group of substrates and the polar amino acids surrounding enzyme's active site. This leads to different proximity and orientation of substrates vis-a-vis their interaction with catalytic residues.
- Kumar, Vijay,Seth, Amit,Kumari, Vijaya,Kumar, Virender,Bhalla, Tek C.
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- METHOD OF PRODUCING BENZOIC ACID
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PROBLEM TO BE SOLVED: To provide a novel synthesis method in the production of a benzoic acid, which is an important compound for the synthesis of an organic compound, and an industrially suitable production method using main materials derived from nonfossil resources. SOLUTION: This invention provides a method of producing a benzoic acid with a substituted hydroxyl group, methoxy group, or acetoxy group, comprising the step of the ozonation of a compound represented by formula (I), where R1 is H, a methyl group or an acetyl group; R2 is H or an acetoxy group; R3 is an alkyl group, a carboxy group, a formyl group, an alkoxycarbonyl group, an amide group, an acid chloride group, a halogenation alkyl group, or a hydroxyalkyl group. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0148-0151
(2016/10/08)
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- Improved selectivity of the production of vanilloids in a recombinant unicellular host
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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 0218-0220; 0221
(2016/01/11)
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- SELECTIVE C-O BOND CLEAVAGE OF OXIDIZED LIGNIN AND LIGNIN-TYPE MATERIALS INTO SIMPLE AROMATIC COMPOUNDS
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A method to cleave C-C and C-0 bonds in β-Ο-4 linkages in lignin or lignin sub-units is described. The method includes oxidizing at least a portion of secondary benzylic alcohol groups in β-Ο-4 linkages in the lignin or lignin sub-unit to corresponding ketones and then leaving C-0 or C-C bonds in the oxidized lignin or lignin sub-unit by reacting it with an organic carboxylic acid, a salt of an organic carboxylic acids, and/or an ester of an organic carboxylic acids. The method may utilize a metal or metal-containing reagent or proceed without the metal or metal-containing reagent.
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- Performance of cobalt titanate towards H2O2 based catalytic oxidation of lignin model compound
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Mixed metal cobalt titanium oxide (CoTiO3) prepared by solution phase method has been evaluated for the liquid phase catalytic oxidation of vainlly alcohol to vanillin using H2O2 as an oxygen source. The morphology, phase composition and crystal structure of the freshly prepared and reused CoTiO3 catalyst was studied by SEM, EDX, XRD, XPS and Raman spectroscopy. Vanillyl alcohol conversion was influenced by various experimental conditions such as reaction time, temperature, molar ratio of reactants, catalyst loading, nature of solvent and reaction medium. The design a heterobimetallic oxide catalyst which can efficiently perform the high conversion and selective oxidation of vanillyl alcohol into fine chemicals, such as vanillin and vanillic acid. It has been found that during the 5 h reaction in NaOH, the CoTiO3 exhibits remarkable conversion of 99% and excellent selectivity of 99.8% to vanillin was achieved in acetic acid and isopropanol solvents, respectively. The oxidation reaction mechanism over the catalyst was postulated based on the observation product from the HPLC analysis. CoTiO3 catalyst can retain its performance without significant change in the catalytic activity after four consecutive cycles.
- Shilpy, Mariom,Ehsan, Muhammad Ali,Ali, Tammar Hussein,Abd Hamid, Sharifah Bee,Ali, Md. Eaqub
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p. 79644 - 79653
(2015/10/05)
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- Enzymatic allylation of catechols
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Enzymatic allylation of catechols was realized via catechol O-methyltransferase (COMT) using an allylated S-adenosyl- L-methionine (allyl-SAM) analog, with relatively good chemoand regioselectivities. This new reaction offered an alternative procedure for allylation of catechols, which can be expanded as a biocatalytic allylation method in organic synthesis.
- Zhang, Yixin,Liu, Wujun,Sohail, Muhammad,Wang, Xueying,Liu, Yuxue,Zhao, Zongbao K.
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supporting information
p. 949 - 951
(2015/08/24)
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- New synthesis of vanillin by degradation of lignin in presence of functional basic ionic liquid
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The degradation of lignin catalyzed by functional basic ionic liquid was investigated. Higher conversion of lignin and simpler degradation product composition were obtained in the presence of basic ionic liquid, comparing with that under traditional NaOH
- Yi, Fengping,Jiang, Xiaoyan,Niu, Jihua,Zhang, Lirong,Wang, Zhen
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p. 885 - 888
(2015/02/05)
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