Production of precursors for anti-Alzheimer drugs: Asymmetric bioreduction in a packed-bed bioreactor using immobilized D. carota cells

Abstract

(S)-1-Phenylethanol derivatives, which are the precursors of many pharmacological products, have also been used as anti-Alzheimer drugs. Bioreduction experiments were performed in a batch and packed-bed bioreactor. Then, the kinetics constants were determined by examining the reaction kinetics in the batch system with free and immobilized carrot cells. Also, the effective diffusion coefficient (D) of acetophenone in calcium alginate-immobilized carrot cells was investigated. Kinetics constants for free cells, which are intrinsic values, are reaction rate V = 0.052 mmol L min, and constants of the Michaelis-Menten K = 2.31 mmol L. Kinetics constants for immobilized cells, which are considered apparent values, are V = 0.0407 mmol L min, K = 3.0472 mmol L for 2 mm bead diameter, and V = 0.0453 mmol L min, K = 4.9383 mmol L for 3 mm bead diameter. Average value of effective diffusion coefficient of acetophenone in immobilized beads was determined as 1.97 × 10 cm s. Using immobilized carrot cells in an up-flow packed-bed reactor, continuous production of (S)-1-phenylethanol through asymmetric bioreduction of acetophenone was performed. The effects of the residence time and concentrations of substrate were investigated at pH 7.6 and 33°C. Enantiomerically pure (S)-1-phenylethanol (ee > 99%) was produced with 75% conversion at 4-hr residence time.

Plant-Mediated Enantioselective Transformation of Indan-1-One and Indan-1-ol

“…In the biological approaches using biocatalysts, optically active alcohols are prepared from prochiral ketones [8][9][10][11], or racemic alcohols as starting materials [8,[12][13][14][15]. Biocatalytic desymmetrization using ketones is highly significant in several processes, as this allows one to obtain pure enantiomer in a 100% theoretical yield.…”

“…Plant biocatalysts have been applied primarily in the reduction of ketones. [8][9][10][11][19][20][21][22][23][24][25]. Biooxidation of alcohols has been described much less [8,[12][13][14][15]22].…”

Plant-Mediated Enantioselective Transformation of Indan-1-one and Indan-1-ol. Part 2

“…Plant cell cultures have been employed for the enantioselective transformation of xenobiotics and have been shown to be good biochemical systems for enantioselective synthesis. Among the used cell and roots cultures, carrots seem to be very efficient for asymmetric reduction of prochiral ketones, not only in the form of crushed pulp [11,12,13,14,15,16,17,18,19,20,21,22] but also cell [17,23,24,25,26] and hairy roots cultures [27]. Based on literature date, [11,28,29,30,31] only few biocatalytic methods were used to obtain indan-1-ol enantiomers.…”