- Syntheses of chiral 1,8-cineole metabolites and determination of their enantiomeric composition in human urine after ingestion of 1,8-cineole- containing capsules
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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.
- Schaffarczyk, Monika,Balaban, Teodor Silviu,Rychlik, Michael,Buettner, Andrea
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- Superacidic cyclization of ω-hydroxygeraniol diacetate and ω-hydroxygeraniol benzyl ether acetate
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Low-temperature superacidic cyclization of (E,E)-3,7-dimethylocta-2,6-diene-1,8-diol (ω-hydroxygeraniol) diacetate and (E,E)-8-acetoxy-1-benzyloxy-3,7-dimethylocta-2,6-diene leads to the same mixtures of two diastereomeric 9-acetoxy-8-hydroxy-p-menth-1-enes epimeric at the C(8) atom.
- Kulcitki,Ungur,Deleanu,Vlad
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p. 136 - 138
(2007/10/03)
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