Biosynthesis Of (S)-3-chloro-1-phenylpropanol, The Intermediate Of Anti-depression Drug(R)-tomoxetine

(S)-3-chloro-1-phenylpropanol is an important building block in thesynthesis of the anti-depression drugs (R)-tomoxetine, fluoxetine andnisoxetine, which are widely used in the treatment of depression. So,preparation of optically active (S)-3-chloro-1-phenylpropanol throughbiological methods will show important practical significance and bringeconomic benefits.In this research, a yeast strain Saccharomyces cerevisiae FU5whichshowed good transformation ability and high activity in asymmetricreduction of3-chloropropiophenone to (S)-3-chloro-1-phenylpropanol hadbeen screened from6strains which preserved by the laboratory. Inmonophasic aqueous system, when the concentration of3-chloropropiophenone was15mmol/L,(S)-3-chloro-1-phenylpropanolcould be obtained after20h of reaction with the yield and enantiomericexcess (e.e.) were65%and98%, respectively.The characteristics of asymmetric reduction of3-chloropropiophenonewith Saccharomyces cerevisiae FU5in monophasic aqueous system had alsobeen comprehensively studied. The results shown that neither substrate norproduct inhibitions were found in the monophasic aqueous system in theasymmetric reduction under the concentration investigated, but the toxicityof product which induced the cell inactivation prevented the yield from beingelevated. The proper concentration of additives in reaction system assisted toimprove the yield, for example, when the concentration of Tween80andβ-cyclodextrin was2.0mmol/L and5.0mmol/L, the yields would beincreased from the control of64.7%to73.8%and70.6%, respectively. Theadditives with the abilities of inclusion and improvement of cell membranepermeability would take better effect on the yield than those only with theability of inclusion. However, no marked promotion on the product e.e. valuewas observed in the system.The asymmetric reduction in aqueous/organic solvent biphasic system has been studied. In aqueous/n-hexane biphasic system, when the volumeratio of buffer to n-hexane was10/1.5(mL/mL), the substrate concentrationwas20mmol/L, the cell concentration was100g/L, the co-substrateconcentration was70g/L,the buffer pH was9.0, the shaking rate was150r/min, and the reaction temperature was28℃, the yield and enantiomericexcess (e.e.) of (S)-3-chloro-1-phenylpropanol were84%and98%afterreaction of40h, respectively. Compared with the monophasic aqueoussystem, the aqueous/n-hexane biphasic system markly improved the substrateconcentration and the yield.Sereval ionic liquids were added to the aqueous/n-hexane biphasicsystem to increase the yield and the e.e.. But the results showed that all ofthe ionic liquids would inhibit the reaction even at a low concentration.Furthermore, the cellular biological characteristics of the yeast had beenstudied in the monophasic aqueous system and aqueous/n-hexane biphasicsystem. The results showed that no significant difference of membraneintegrality rather than the fluidity of membrane were observed in thedifferent reaction system.