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    Asymmetric reduction of prochiral aromatic and hetero aromatic ketones using whole-cell of Lactobacillus senmaizukei biocatalyst
    (Taylor & Francis Inc, 2021) Colak, Nida Sezin; Kalay, Erbay; Sahin, Engin
    Asymmetric bioreduction of aromatic and heteroaromatic ketones is an important process in the production of precursors of biologically active molecules. In this study, the bioreduction of aromatic and hetero aromatic prochiral ketones into optically active alcohols was investigated using Lactobacillus senmaizukei as a whole-cell catalyst, since whole-cells are less expensive than pure enzymes. The study indicates enantioselective bioreduction of various substituted aromatic ketones (1-16) to the corresponding (R)-and (S)-chiral secondary alcohols (1a-16a) in low to excellent enantioselectivity (6-94%) with good yields (58-95%). In addition, heteroaromatic prochiral ketones 1-(pyridin-2-yl)ethanone (17) and 1-(furan-2-yl)ethanone (18) were reduced to (R)-17a and (R)-18a in enantiopure form with excellent conversion (>99%) and yields. These findings show that L. senmaizukei is a very important biocatalyst for asymmetric reduction of both 6-membered and 5-member heteroaromatic methyl ketones. This method promising a green synthesis for the synthesis of biologically important secondary chiral alcohols in an environmentally friendly and inexpensive process.
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    Response surface methodology as optimization strategy for asymmetric bioreduction of acetophenone using whole cell of Lactobacillus senmaizukei
    (Taylor & Francis Inc, 2019) Colak, Nida Sezin; Sahin, Engin; Dertli, Enes; Yilmaz, Mustafa Tahsin; Taylan, Osman
    Whole cell applications are one of the main methodologies for the bioreduction of prochiral ketones to obtain enantiomerically rich chiral secondary alcohols which are mainly affected by the culture parameters of the whole cell. In this study, whole cell of Lactobacillus senmaizukei as a safe Lactic Acid Bacteria (LAB) was used for the reduction of acetophenone and Response Surface Methodology (RSM) application was used to optimize the culture parameters in terms of temperature, pH, incubation time, and agitation level to obtain the highest enantiomeric excess (ee) and conversion rate. The predicted optimum conditions for the bioreduction with whole cell Lactobacillus senmaizukei were found to be pH of 5.25, temperature of 25 degrees C, incubation time of 72 hr, and agitation level of 100 rpm. Importantly, the efficiency of the reduction of the acetophenone was significantly affected by the linear and quadratic effects of culture parameters. These findings are important to show the role of culture parameters for the bioreduction reactions and also the efficiency of the RSM technique to optimize these parameters.