18679-48-6Relevant articles and documents
Dysprosium-doped zinc tungstate nanospheres as highly efficient heterogeneous catalysts in green oxidation of terpenic alcohols with hydrogen peroxide
Batalha, Daniel Carreira,Mesquita Borges, Kellen Cristina,de Fátima Gon?alves, Rosana,de Matos Rodrigues, Murillo Henrique,Godinho, Mário Júnior,Fajardo, Humberto Vieira,de Oliveira Bruziquesi, Carlos Giovani,da Silva, Márcio José
, p. 6661 - 6670 (2021/04/22)
A green route to oxidize terpenic alcohols (nerol and geraniol) with H2O2over a solid catalyst was developed. The Dy-doped ZnWO4catalyst was synthesized by coprecipitation and microwave-assisted hydrothermal heating, containing different dysprosium loads. All the catalysts were characterized through infrared spectroscopy, powder X-ray diffraction, surface area and porosimetry, transmission electronic microscopy image, andn-butylamine potentiometric titration analyses. The influence of main reaction parameters such as temperature, the stoichiometry of reactants, loads, and catalyst nature was assessed. ZnWO42.0 mol% Dy was the most active catalyst achieving the highest conversion (98%) and epoxide selectivity (78%) in nerol oxidation. The reaction scope was extended to other terpenic alcohols (i.e., geraniol, borneol, and α-terpineol). The highest activity of ZnWO42.0 mol% Dy was assigned to the lower crystallite size, higher surface area and pore volume, higher acidity strength and the greatest dysprosium load.
Syntheses of chiral 1,8-cineole metabolites and determination of their enantiomeric composition in human urine after ingestion of 1,8-cineole- containing capsules
Schaffarczyk, Monika,Balaban, Teodor Silviu,Rychlik, Michael,Buettner, Andrea
, p. 77 - 85 (2013/06/27)
The chiral metabolites in human urine were investigated after ingestion of a 1,8-cineole (eucalyptol)-containing enterocoated capsule (Soledum). For identification of the various enantiomers the enantiomerically pure (-/+)-α2-hydroxy-1,8- cineole, (-/+)-β2-hydroxy-1,8-cineole, (-/+)-9-hydroxy-1,8-cineole, and (-/+)-2-oxo-1,8-cineole were prepared. To achievethis aim, after acetylation of the synthesized racemic 2-and 9-hydroxy-1,8-cineoles, pig liver esterase- or yeast-mediated hydrolysis provided the (-)-alcohols with their antipodal(+)-acetates with enantiomeric excess of 33-100 %. Dess-Martin periodinane oxidation of the alcohol (+)-α2-hydroxy-1,8-cineole, obtained by hydrolysis of the resolved acetate, provided the corresponding (+)-2-oxo-1,8-cineole, meanwhile the oxidation of (-)-α2-hydroxy-1,8-cineole gave (-)-2-oxo-1,8-cineole. Using these standards seven metabolites (+/-)-α2-hydroxy-1,8-cineole, (+/-)-β2-hydroxy-1,8-cineole, (+/-)-α3-hydroxycineole,(+/-)-3-oxo-1, 8-cineole, 4-hydroxy-1,8-cineole, 7-hydroxy-1,8-cineole, and (+/-)-9-hydroxy-1,8-cineole, all liberated from their glucuronides, were identified in urine by GCMS on a chiral stationary phase after consumption of 10 mg of 1,8-cineole. Metabolite screening using 2H3-1,8- cineol as the internal standard revealed (+/-)-α2-hydroxy-1,8-cineole as the predominant metabolite followed by (+/-)-9-hydroxy-1,8-cineole. Furthermore, the results showed that one enantiomer is always formed preferentially.
Cineole biodegradation: Molecular cloning, expression and characterisation of (1R)-6β-hydroxycineole dehydrogenase from Citrobacter braakii
Slessor, Kate E.,Stok, Jeanette E.,Cavaignac, Sonia M.,Hawkes, David B.,Ghasemi, Younes,De Voss, James J.
experimental part, p. 81 - 86 (2010/05/17)
The first steps in the biodegradation of 1,8-cineole involve the introduction of an alcohol and its subsequent oxidation to a ketone. In Citrobacter braakii, cytochrome P450cin has previously been demonstrated to perform the first oxidation to produce (1R)-6β-hydroxycineole. In this study, we have cloned cinD from C. braakii and expressed the gene product, which displays significant homology to a number of short-chain alcohol dehydrogenases. It was demonstrated that the gene product of cinD exhibits (1R)-6β-hydroxycineole dehydrogenase activity, the second step in the degradation of 1,8-cineole. All four isomers of 6-hydroxycineole were examined but only (1R)-6β-hydroxycineole was converted to (1R)-6-ketocineole. The (1R)-6β-hydroxycineole dehydrogenase exhibited a strict requirement for NAD(H), with no reaction observed in the presence of NADP(H). The enzyme also catalyses the reverse reaction, reducing (1R)-6-ketocineole to (1R)-6β-hydroxycineole. During this study the N-terminal His-tag used to assist protein purification was found to interfere with NAD(H) binding and lower enzyme activity. This could be recovered by the addition of Ni2+ ions or proteolytic removal of the His-tag.
