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Deracemization of secondary alcohols by chemo-enzymatic sequence with plant cells

Magallanes-Noguera, Cynthia, Ferrari, Mónica M., Kurina-Sanz, Marcela, Orden, Alejandro A.
Journal of biotechnology 2012 v.160 no.3-4 pp. 189-194
Gardenia jasminoides, alcohols, biocatalysts, calcium alginate, cells, enzymes, immobilized cells, oxidation, screening, viability
A screening based on undifferentiated plant cells allowed identifying Gardenia jasminoides as the best biocatalyst to perform the kinetic resolution of 1-phenylethanol. This species was further tested for its ability to oxidize stereoselectively the (S)-isomers from racemic mixtures of secondary alcohols leaving their antipodes unaffected in Tris–HCl buffer. Those substrates which afforded the best results in the kinetic resolution were subjected to a chemo-enzymatic sequence of deracemization. G. jasminoides immobilized cells in calcium alginate were used for the oxidation of the (S)-enantiomers and, in a second step, NaBH₄ was added to the same vessel for the reduction of the corresponding ketone. The sequential repetition of these two steps allowed obtaining the R-alcohols in 82–90% yield in high optical purity (71–96% ee). Despite the viability of the cells is affected by the chemical reagent, their enzymes remain active due to the protective environment of the calcium alginate beads.