Whole‐Cell Carboxylate Reduction for the Synthesis of 3‐Hydroxytyrosol. Issue 4 (17th January 2014)

• Record Type: Journal Article
• Authors: Napora‐Wijata, Kamila; Robins, Karen; Osorio‐Lozada, Antonio; Winkler, Margit
• Is Part Of: ChemCatChem. Volume 6:Issue 4(2014:Apr.)
• Page Start: 1089
• Page End: 1095
• Publication Date: 2014-01-17
• Subjects: antioxidants -- biocatalysis -- carboxylic acids -- cofactors -- reduction; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201300913
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: 3‐Hydroxytyrosol (3‐HT) is a phenolic antioxidant that has a number of beneficial effects on human health and is a valuable building block in the synthesis of various pharmaceuticals. Herein, we report a new method for the production of 3‐HT through reduction of 3, 4‐dihydroxyphenylacetic acid. The reduction was performed in whole Escherichia coli BL21 (DE3) cells overexpressing carboxylic acid reductase from Nocardia and phosphopantetheinyl transferase from E. coli. An endogenous E. coli aldehyde reducing activity turned out to be highly efficient for further reduction of the aldehyde intermediate to the desired alcohol. The influence of different buffer components, cofactors, and cofactor recycling systems was investigated. A very economic combination of glucose, citrate, and air proved sufficient for recycling of the essential cofactors ATP and NAD(P)H. Selected crucial parameters were then further optimized within a "design of experiments" approach. Finally, first preparative‐scale bioreductions resulted in pure 3‐HT. Abstract : All in a cell's work: An enzymatic carboxylic acid reduction is the key step of a new route to the potent antioxidant from olives: 3‐hydroxytyrosol. In addition to the substrate 3, 4‐dihydroxyphenylacetic acid, only citrate, glucose, and oxygen are required to regenerate the essential cofactors ATP and NAD(P)H. CAR=carboxylate reductase; PPTase= phosphopantetheinyl transferase.