- Heterologous expression of geraniol dehydrogenase for identifying the metabolic pathways involved in the biotransformation of citral by Acinetobacter sp. Tol 5
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The biotransformation of citral, an industrially important monoterpenoid, has been extensively studied using many microbial biocatalysts. However, the metabolic pathways involved in its biotransformation are still unclear, because citral is a mixture of the trans-isomer geranial and the cis-isomer neral. Here, we applied the heterologous expression of geoA, a gene encoding geraniol dehydrogenase that specifically converts geraniol to geranial and nerol to neral, to identify the metabolic pathways involved in the biotransformation of citral. Acinetobacter sp. Tol 5 was employed in order to demonstrate the utility of this methodology. Tol 5 transformed citral to (1R,3R,4R)-1-methyl-4-(1-methylethenyl)-1,3-cyclohexanediol and geranic acid. Biotransformation of citral precursors (geraniol and nerol) by Tol 5 transformant cells expressing geoA revealed that these compounds were transformed specifically from geranial. Our methodology is expected to facilitate a better understanding of the metabolic pathways involved in the biotransformation of substrates that are unstable and include geometric isomers.
- Usami, Atsushi,Ishikawa, Masahito,Hori, Katsutoshi
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p. 2012 - 2020
(2018/11/06)
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- Reactions of allyl alcohols of the pinane series and of their epoxides in the presence of montmorillonite clay
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The reactivity of allyl alcohols of the pinane series and of their epoxides in the presence of montmorillonite clay in intra- and intermolecular reactions was studied. Mutual transformations of (+)-trans-pino-carveol ((+)-2) and (-)-myrtenol ((-)-3a) were major reactions of these compounds on askanite-bentonite clay (Schemes 1 and 2). However, the two reactions gave different isomerization products, indicating that the reactivity of the starting alcohol (+)-2 or (-)-3a was different from that of the same compound (+)-2 or (-)-3 formed in the course of the reactions, (-)-cis- and (+)-trans-Verbenol ((-)-16 and (+)-12, resp.), as well as (-)-cis-verbenol epoxide ((-)-20) reacted with both aliphatic and aromatic aldehydes on askanite-bentonite clay giving various heterocyclic compounds (Schemes 4, 5 and 7); the reaction path depended on the structure of both the terpenoid and the aldehyde.
- Il'ina, Irina V.,Volcho, Konstantin P.,Korchagina, Dina V.,Barkhash, Vladimir A.,Salakhutdinov, Nariman F.
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p. 353 - 368
(2008/02/08)
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- A SHORT AND EFFICIENT METHOD FOR THE PREPARATION OF α,p-DIMETHYLSTYRENE FROM CITRAL
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Acid catalysed cyclization of citral to give α,p-dimethyl styrene using chloranil as an oxidizing agent is reported.The important aspect of this transformation is the dehydration of intermediate piperitenol followed by dehydrogenation to furnish the target compound in 80.5percent yield.
- Barton, Derek H. R.,Parekh, Shyamal I.
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p. 3353 - 3362
(2007/10/02)
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- Acid-catalysed Terpenylations of Olivetol in the Synthesis of Cannabinoids
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Examination of the toluene-p-sulphonic acid-catalysed reaction of (1S,2S,3R,6R)-(+)-trans-car-2-ene epoxide with olivetol shows that, inconsistently with the accepted mechanism, (3R,4R)-(-)-o- and -p-cannabidiols are produced as well as (3R,4R)-(-)-Δ1- and Δ6-tetrahydrocannabinols.Evidence is now presented that, as in Petrzilka's reaction employing chiral p-mentha-2,8-dien-1-ols, the reacting species is the delocalised (4R)-p-mentha-2,8-dien-1-yl cation (9).Similar terpenylation using (1S,3S,4R,6R)-(+)-trans-car-3-ene epoxide shows that besides the reported (-)-Δ6-THC, o- and p-cannabidiols, Δ1-THC and Δ4,8-iso-THC can also be produced.The nature of the products, the chirality, and the characteristics of the reaction implicate again the delocalised cation (9).Its formation via Kropp-type rearrangement is excluded and a pathway leading to (4R)-p-mentha-2,6,8-triene, which on protonation gives (9), is proposed.Protonated on C-8, the triene can be trapped and isolated as (4R)-p-mentha-2,6-dien-8-ol.The latter, made in (+/-)-form from citral, proved to be an excellent terpenylating agent for producing cannabinoids.Terpenylation of olivetol by the pinanes (1S,4S,5S)-(-)-cis-verbenol and (1R,5S,7R)-(+)-cis-chrysanthenol is compared.A major drawback of the latter is partial racemisation which occurs in the verbenone-chrysanthenone isomerisation during its photochemical preparation.Whilst Δ1-THC cannot be directly obtained from verbenol, its tertiary allylic cation permits a much higher yielding terpenylation than the secondary cation from chrysanthenol.
- Crombie, Leslie,Crombie, W. Mary L.,Jamieson, Sally V.,Palmer, Christopher J.
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p. 1243 - 1250
(2007/10/02)
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