Bioreduction using

The reactions shown here illustrate the versatility of yeast, bacterial, and fungal reductions. In all these cases, screening studies were usually conducted first followed by refinement of the bioreduction using the best microorganism. Other examples where reductions are used to produce pharmaceutical intermediates can be found in a review by Patel.107... 

Scheme4.10 Whole-cell bioreduction using a two phase system.

Scheme 2.120 Stereocomplementary bioreduction using a Prelog and anti-Prelog dehydrogenase...

Paul, C.E., Gargiulo, S., Opperman, D.J., Lavandera, 1., Gotor-Femandez, V., Gotor, V., Taglieber, A., Arends, I.W.C.E., and Hollmann, F. (2013) Mimicking nature synthetic nicotinamide cofactors for C=C bioreduction using enoate reductases. Org. Lett., 15,180-183. 

Acetophenone-type compounds dominate in the literature and are a successful class of compounds for bioreductions using CRED enzymes. Their simple availability, minimal steric hindrance around the ketone, and excellent solubility in a range of solvents make them useful substrates for further study. 

Concurrent biooxidation and bioreduction using CRED technology. 

V. Armendariz, Bioreduction of Gold(III) to Gold(O) and Nanoparticle Formation by Oat and Wheat Biomasses The Use of Plants in Nanobiotechnology. Master Thesis, the University of Texas at El Paso, Chemistry Department, El Paso, TX, 2005, p. 107. 

Biological activity can be used in two ways for the bioremediation of metal-contaminated soils to immobilize the contaminants in situ or to remove them permanently from the soil matrix, depending on the properties of the reduced elements. Chromium and uranium are typical candidates for in situ immobilization processes. The bioreduction of Cr(VI) and Ur(VI) transforms highly soluble ions such as CrO and UO + to insoluble solid compounds, such as Cr(OH)3 and U02. The selenate anions SeO are also reduced to insoluble elemental selenium Se°. Bioprecipitation of heavy metals, such as Pb, Cd, and Zn, in the form of sulfides, is another in situ immobilization option that exploits the metabolic activity of sulfate-reducing bacteria without altering the valence state of metals. The removal of contaminants from the soil matrix is the most appropriate remediation strategy when bioreduction results in species that are more soluble compared to the initial oxidized element. This is the case for As(V) and Pu(IV), which are transformed to the more soluble As(III) and Pu(III) forms. This treatment option presupposes an installation for the efficient recovery and treatment of the aqueous phase containing the solubilized contaminants. 

Stuermer, R., Hauer, B., Hall, M. and Faber, K. (2007) Asymmetric bioreduction of activated C C bonds using enoate reductases from the old yellow enzyme family. Current Opinion in Chemical Biology, 11, 203-213. 

Itoh, N., Nakamura, M., Inoue, K. and Makino, Y. (2007) Continuous production of chiral 1,3-butanediol using immobilized biocatalysts in a packed bed reactor promising biocatalysis method with an asymmetric hydrogen-transfer bioreduction. Applied Microbiology and Biotechnology, 75 (6), 1249-1256. 

Transmission electron microscopy energy dispersive X-ray analysis has also been used to image intracellular Se granules present from Se bioreduction in bacteria. Reduction of selenite and the deposition of elemental Se in cell cytoplasm or in the extracellular space may be lead to promising bioremediation schemes.172... 

Burgos WD, Royer RA, Fang Y, Yeh GT, Fisher AS, Jeon BH, Dempsey BA (2002) Theoretical and experimental considerations related to reaction-based modeling a case study using Iron(III) oxide bioreduction. Geomicro J 19 253-287... 

Welch, C. J., Grau, B., Moore, J. and Mathre, D., Use of chiral HPLC-MS for rapid evaluation of the yeast-mediated enantioselective bioreduction of a diaryl ketone. J. Org. Chem., 2001, 66, 6836. 

Oxidoreductases are, after lipases, the second most-used kinds of biocatalysts in organic synthesis. Two main processes have been reported using this type of enzymes-bioreduction of carbonyl groups [39] and biohydroxylation of non-activated substrates [40]. However, in recent few years other processes such as deracemization of amines or alcohols [41] and enzymatic Baeyer-Villiger reactions of ketones and aldehydes [42] are being used with great utility in asymmetric synthesis. 

The reduction of other carbonyHc compounds such as 1,3-diketones or 3-oxo esters has also been extensively successfully described in the literature. In this manner, (R)-fluoxetine can be also synthesized through the bioreduction of ethyl benzoylacetate using Geotrichum sp. G38 that shows a complementary selectivity to the one shown by baker s yeast (Scheme 10.19) [47]. 

R.J. Flodgkiss, Use of 2-nitroimidazoles as bioreductive markers for tumour hypoxia. Anticancer Drug Des. 13 (1998) 687-702. 

Dinitrobenzene, which is used widely in the production of pesticides and dyes, causes testicular cancer in the rat. The compound displays the prototypical aerobic metabolism of the nitroaromatics, namely bioreduction to a radical anion, followed by electron transfer to oxygen ... 

Nitrofurantoin, a anti-microbial agent under investigation for use in cancer therapy, also undergoes bioreduction to a nitro radical anion. Following earlier, contradictory reports, Miller et al. have re-examined the possibility that NF can oxidise GSH. Using three different methods of NF generation, the authors found no evidence for reaction between GSH and the radical.127... 

In summary, organisms can use biological reductants such as NAD(P)H, capable of hydride transfer (two electron transfer), and reduced flavoproteins and metallo-proteins, capable of single electron donation. Although not necessarily intended to interact with xenobiotic organic compounds, when such organic chemicals come in contact with suitably reactive bioreductants in vivo, reductions can occur. 

Tirapazamine (SR 4233) is the lead compound to a class of bioreductive anticancer drugs that makes use of the fact that solid tumors are hypoxic (Brown 1990, 1993 Brown and Wang 1998) and clinical phase III trials are under the way (Gandara et al. 2002). With an anticancer drug that is that far advanced in clinical trials one would like to know the mechanism of its action. Obviously, this has attracted many research teams that are expert in different techniques to tackle the problem. It will be shown below that there is now a host of first-class information, but it is as yet difficult, if not impossible, to arrive at a conclusive mechanism of its action. 

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