Journal articles: 'Hydroxylation reactions'

1

Holland, Herbert L., Frances M. Brown, P. Chinna Chenchaiah, and J. Appa Rao. "Hydroxylation of prostanoids by fungi. Synthesis of (−)-15-deoxy-19-(R)-hydroxy-PGE1 and (−)-15-deoxy-18-(S)-hydroxy-PGE1." Canadian Journal of Chemistry 68, no. 2 (February 1, 1990): 282–93. http://dx.doi.org/10.1139/v90-039.

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A series of racemic substituted cyclopentanones, with alkyl groups corresponding to the upper prostanoid side chain and (or) the lower prostanoid side chain without the C-15 alcohol, has been synthesized. Using a steroid template for the prostanoid molecule as a basis for selection, fungi capable of hydroxylating steroids have been used to biotransform the prostanoid substrates. The predominant products were hydroxylated at the prostanoid C-18 and C-19 positions. The hydroxylations were enantioselective, with excesses in the range 10–60%, and in most cases the predominant configuration corresponded to that of the natural prostanoids. The stereochemistry of the C-19 hydroxyl group was found to be R by degradation of products to methyl 6-acetoxyheptanoate and comparison of that material with a resolved sample, obtained via crystallization of the brucine salt of ethyl 6-phthaloxyheptanoate. Hydroxylation at C-18 gave the S configuration of alcohol. Hydroxylation at prostanoid C-15 was observed, but in all cases this was accompanied by other reactions. Hydroxylation of Rhizopusarrhizus has been used in a preparation of (−)-15-deoxy-19-(R)-hydroxy-PGE1 and (−)-15-deoxy-18-(S)-hydroxy-PGE1. Keywords: biotransformation, hydroxylation, prostaglandins, prostanoids.

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2

Holland, Herbert L., and Hedda K. Weber. "Enzymatic hydroxylation reactions." Current Opinion in Biotechnology 11, no. 6 (December 2000): 547–53. http://dx.doi.org/10.1016/s0958-1669(00)00142-7.

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3

Zimniak, P., E. J. Holsztynska, A. Radominska, M. Iscan, R. Lester, and D. J. Waxman. "Distinct forms of cytochrome P-450 are responsible for 6β-hydroxylation of bile acids and of neutral steroids." Biochemical Journal 275, no. 1 (April 1, 1991): 105–11. http://dx.doi.org/10.1042/bj2750105.

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Cytochrome P-450-dependent 6 beta-hydroxylation of bile acids in rat liver contributes to the synthesis of the quantitatively important pool of 6-hydroxylated bile acids, as well as to the detoxification of hydrophobic bile acids. The lithocholic acid 6 beta-hydroxylation reaction was investigated and compared with androstenedione 6 beta-hydroxylation. Differential responses of these two activities to inducers and inhibitors of microsomal P-450 enzymes, lack of mutual inhibition by the two substrates and differential inhibition by antibodies raised against several purified hepatic cytochromes P-450 were observed. From these results it was concluded that 6 beta-hydroxylation of lithocholic acid is catalysed by P-450 form(s) different from the subfamily IIIA cytochromes P-450 which are responsible for the bulk of microsomal androstenedione 6 beta-hydroxylation. Similar, but more tentative, results revealed that the 7 alpha-hydroxylation of lithocholic acid and of androstenedione may be also catalysed by distinct P-450 enzymes. The results indicate that cytochromes P-450 hydroxylating bile acids are distinct from analogous enzymes that carry out reactions of the same regio- and stereo-specificity on neutral steroids (steroid hormones). A comparison of pairs of cytochromes P-450 that catalyse the same reaction on closely related steroid molecules will help to define those structural elements in the proteins that determine the recognition of their respective substrates.

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4

Fan, Tengjiao, Guohui Sun, Lijiao Zhao, Xin Cui, and Rugang Zhong. "Metabolic Activation and Carcinogenesis of Tobacco-Specific Nitrosamine N’-Nitrosonornicotine (NNN): A Density Function Theory and Molecular Docking Study." International Journal of Environmental Research and Public Health 16, no. 2 (January 9, 2019): 178. http://dx.doi.org/10.3390/ijerph16020178.

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N’-nitrosonornicotine (NNN) is one of the tobacco-specific nitrosamines (TSNAs) that exists widely in smoke and smokeless tobacco products. NNN can induce tumors in various laboratory animal models and has been identified by International Agency for Research on Cancer (IARC) as a human carcinogen. Metabolic activation of NNN is primarily initiated by cytochrome P450 enzymes (CYP450s) via 2′-hydroxylation or 5′-hydroxylation. Subsequently, the hydroxylating intermediates undergo spontaneous decomposition to generate diazohydroxides, which can be further converted to alkyldiazonium ions, followed by attacking DNA to form various DNA damages, such as pyridyloxobutyl (POB)-DNA adducts and pyridyl-N-pyrrolidinyl (py-py)-DNA adducts. If not repaired correctly, these lesions would lead to tumor formation. In the present study, we performed density functional theory (DFT) computations and molecular docking studies to understand the mechanism of metabolic activation and carcinogenesis of NNN. DFT calculations were performed to explore the 2′- or 5′- hydroxylation reaction of (R)-NNN and (S)-NNN. The results indicated that NNN catalyzed by the ferric porphyrin (Compound I, Cpd I) at the active center of CYP450 included two steps, hydrogen abstraction and rebound reactions. The free energy barriers of the 2′- and 5′-hydroxylation of NNN are 9.82/8.44 kcal/mol (R/S) and 7.99/9.19 kcal/mol (R/S), respectively, suggesting that the 2′-(S) and 5′-(R) pathways have a slight advantage. The free energy barriers of the decomposition occurred at the 2′-position and 5′-position of NNN are 18.04/18.02 kcal/mol (R/S) and 18.33/19.53 kcal/mol (R/S), respectively. Moreover, we calculated the alkylation reactions occurred at ten DNA base sites induced by the 2′-hydroxylation product of NNN, generating the free energy barriers ranging from 0.86 to 4.72 kcal/mol, which indicated that these reactions occurred easily. The docking study showed that (S)-NNN had better affinity with CYP450s than that of (R)-NNN, which was consistent with the experimental results. Overall, the combined results of the DFT calculations and the docking obtained in this study provide an insight into the understanding of the carcinogenesis of NNN and other TSNAs.

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5

Holland, Herbert L. "ChemInform Abstract: Stereoselective Hydroxylation Reactions." ChemInform 32, no. 21 (May 26, 2010): no. http://dx.doi.org/10.1002/chin.200121255.

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6

Dardonville, Christophe, Henri Virelizier, Jean Boivin, and Christopher K. Jankowski. "Reactions of carboline." Spectroscopy 13, no. 4 (1997): 257–64. http://dx.doi.org/10.1155/1997/821241.

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The reactions of carboline under various oxidative conditions are reported. The soft aerobic radiolysis, hydroxylation and rearrangement transformations are studied using isotopic labelling and GC–MS techniques.

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7

Cryle, Max J., Jeanette E. Stok, and James J. De Voss. "Reactions Catalyzed by Bacterial Cytochromes P450." Australian Journal of Chemistry 56, no. 8 (2003): 749. http://dx.doi.org/10.1071/ch03040.

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The cytochromes P450 are a large family of oxidative haemoproteins that are responsible for a wide variety of oxidative transformations in a variety of organisms. This review focuses upon the reactions catalyzed specifically by bacterial enzymes, which includes aliphatic hydroxylation, alkene epoxidation, aromatic hydroxylation, oxidative phenolic coupling, heteroatom oxidation and dealkylation, and multiple oxidations including C–C bond cleavage. The potential for the practical application of the oxidizing power of these enzymes is briefly discussed.

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8

Agarwal, Mahadev, Neelam Singla, and S. K. Singh. "To Synthesis and Characterization of Novel 1,3,4-Oxadiazinoindole Derivatives for the Purpose of Antidepressant Activity." INTERNATIONAL JOURNAL OF PHARMACEUTICAL QUALITY ASSURANCE 14, no. 03 (September 25, 2023): 656–60. http://dx.doi.org/10.25258/ijpqa.14.3.33.

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The present paper is based on the combination of MAOI hydrazide moiety and tricyclic antidepressant moiety. This combination investigates new compounds as 1,3,4-oxadiazinoindole derivatives to find potent and safer antidepressants. Synthesis of 1,3,4-oxadiazinoindole derivatives are started from various animoacids. The sequence of synthesis reactions such as benzoylation reaction, Halo-De-hydroxylation (Nucleophilic substitution reaction), Schotten-Baumann reaction, Nucleophilic addition and finally cyclization reaction (Cyclo-De-Hydroxylation) are involved. Synthesized compounds are characterized via melting point, TLC, FT infrared spectroscopy, 1H-NMR, and mass spectroscopy techniques. All compound’s structures are confirmed.

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9

Paul, Melanie, Alexander Hoffmann, and Sonja Herres-Pawlis. "Room temperature stable multitalent: highly reactive and versatile copper guanidine complexes in oxygenation reactions." JBIC Journal of Biological Inorganic Chemistry 26, no. 2-3 (February 17, 2021): 249–63. http://dx.doi.org/10.1007/s00775-021-01849-9.

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AbstractInspired by the efficiency of natural enzymes in organic transformation reactions, the development of synthetic catalysts for oxygenation and oxidation reactions under mild conditions still remains challenging. Tyrosinases serve as archetype when it comes to hydroxylation reactions involving molecular oxygen. We herein present new copper(I) guanidine halide complexes, capable of the activation of molecular oxygen at room temperature. The formation of the reactive bis(µ-oxido) dicopper(III) species and the influence of the anion are investigated by UV/Vis spectroscopy, mass spectrometry, and density functional theory. We highlight the catalytic hydroxylation activity towards diverse polycyclic aromatic alcohols under mild reaction conditions. The selective formation of reactive quinones provides a promising tool to design phenazine derivatives for medical applications. Graphic abstract

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10

Cadot, Christine, Peter I. Dalko, Janine Cossy, Cyril Ollivier, Rachel Chuard, and Philippe Renaud. "Free-Radical Hydroxylation Reactions of Alkylboronates." Journal of Organic Chemistry 67, no. 21 (October 2002): 7193–202. http://dx.doi.org/10.1021/jo0201833.

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11

Lee, Gun Dae, Sung Gab Kim, Hee Hoon Jeong, Seong Soo Park, and Seong Soo Hong. "Photocatalytic Hydroxylation of Phenol over Ti-Containing Zeolites (TS-1, Ti-MCM-41)." Solid State Phenomena 124-126 (June 2007): 1793–96. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1793.

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The photo-catalytic hydroxylation of phenol with hydrogen peroxide was carried out over TS-1 and Ti-MCM-41 catalysts. For comparison, the dark (thermal)-catalytic hydroxylation of phenol was also performed. The difference in catalytic behaviors of TS-1 and Ti-MCM-41 and product distribution in both the reactions were investigated. The TS-1 and Ti-MCM-41 catalysts having the Si/Ti ratio of 50 were prepared by in-situ crystallization and characterized using XRD, UV-DRS. In the all reactions, the main products were catechol (CAT), hydroquinone (HQ) and benzoquinone (BQ). In dark (thermal)-reaction, TS-1 showed a higher catalytic activity than Ti- MCM-41. In photo-reaction, however, the activity of Ti-MCM-41 was comparable to that of TS-1. The conversion of phenol and the selectivity to CAT in the photo-catalytic reaction were higher than those in dark (thermal)-reaction. In the all reactions, the selectivity to CAT increased remarkably when the selectivities to HQ and BQ decreased with reaction time.

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12

Flashman, Emily, Sarah L. Davies, Kar Kheng Yeoh, and Christopher J. Schofield. "Investigating the dependence of the hypoxia-inducible factor hydroxylases (factor inhibiting HIF and prolyl hydroxylase domain 2) on ascorbate and other reducing agents." Biochemical Journal 427, no. 1 (March 15, 2010): 135–42. http://dx.doi.org/10.1042/bj20091609.

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The HIF (hypoxia-inducible factor) hydroxylases [PHDs or EGLNs (prolyl hydroxylases), which in humans are PHD isoforms 1–3, and FIH (factor inhibiting HIF)] regulate HIF levels and activity. These enzymes are Fe(II)/2-oxoglutarate-dependent oxygenases, many of which are stimulated by ascorbate. We have investigated the ascorbate dependence of PHD2-catalysed hydroxylation of two prolyl hydroxylation sites in human HIF-1α, and of FIH-catalysed hydroxylation of asparaginyl hydroxylation sites in HIF-1α and in a consensus ankyrin repeat domain peptide. The initial rate and extent of hydroxylation was increased in the presence of ascorbate for each of these reactions. When ascorbate was replaced with structural analogues, the results revealed that the ascorbate side chain was not important in its contribution to HIF hydroxylase catalysis, whereas modifications to the ene-diol portion of the molecule negated the ability to promote hydroxylation. We investigated whether alternative reducing agents (glutathione and dithiothreitol) could be used to promote HIF hydroxylase activity, and found partial stimulation of hydroxylation in an apparently enzyme- and substrate-specific manner. The results raise the possibility of developing reducing agents targeted to specific HIF hydroxylase-catalysed reactions.

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13

Morrone, Dana, Xiaoming Chen, Robert M. Coates, and Reuben J. Peters. "Characterization of the kaurene oxidase CYP701A3, a multifunctional cytochrome P450 from gibberellin biosynthesis." Biochemical Journal 431, no. 3 (October 11, 2010): 337–47. http://dx.doi.org/10.1042/bj20100597.

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KO (kaurene oxidase) is a multifunctional cytochrome P450 catalysing three sequential oxidations in gibberellin phytohormone biosynthesis. These serve to transform the C4α methyl of the ent-kaurene olefin intermediate into the carboxylic acid moiety of ent-kauren-19-oic acid. To investigate the unknown catalytic mechanism and properties of KO, we have engineered the corresponding CYP701A3 from Arabidopsis thaliana (AtKO) for functional recombinant expression in Escherichia coli, involving use of a fully codon-optimized construct, along with additional N-terminal deletion and modification. This recombinant AtKO (rAtKO) was used to carry out 18O2 labelling studies with ent-kaurene, and the intermediates ent-kaurenol and ent-kaurenal, to investigate the multifunctional reaction sequence; revealing catalysis of three hydroxylation reactions, which further requires dehydration at some stage. Accordingly, following initial hydroxylation, ent-kaurenol must then be further hydroxylated to a gem-diol intermediate, and our data indicate that the subsequent reactions proceed via dehydration of the gem-diol to ent-kaurenal, followed by an additional hydroxylation to directly form ent-kaurenoic acid. Kinetic analysis indicates that these intermediates are all retained in the active site during the course of the reaction series, with the first hydroxylation being rate-limiting. In addition, investigation of alternative substrates demonstrated that ent-beyerene, which differs in ring structure distal to the C4α methyl, is only hydroxylated by rAtKO, indicating the importance of the exact tetracyclic ring structure of kaurane for multifunctional KO activity. Thus the results of the present study clarify the reaction sequence and enzymatic mechanism of KO, as well as substrate features critical for the catalysed multiple reaction sequence.

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14

Singh, Kuldeep, Kulbir Kulbir, Tarang Gupta, Rajneesh Kaur, and Raman Singh. "Applications of Rozen’s Reagent in Oxygen-Transfer and C–H Activation Reactions." Synthesis 51, no. 02 (November 22, 2018): 371–83. http://dx.doi.org/10.1055/s-0037-1609638.

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Rozen’s reagent (hypofluorous acid–acetonitrile complex, HOF·MeCN) is a robust nonspecific oxygen-transfer reagent and became a proven tool for the oxidation of difficult-to-oxidize molecules. It has been applied to instant oxygen transfers to functional groups such as alkenes, alkynes, and aromatic hydrocarbons, epoxidation, oxidation of alcohols, amines, and alkynes, oxygen-transfer reactions with nitrogen, phosphorus, and sulfur-containing substrates, and α-hydroxylation of carbonyl groups. Apart from being a potential green oxidizing agent, the complex has applications in 18O-labeling and C–H functionalization strategies. Recent uses of Rozen’s reagent in developing nanomaterials and oxidized expanded graphite indicate the enormous potential of the reagent. These aspects are discussed in this review.1 Introduction2 Synthesis and Physical Properties3 Safety and Handling4 Oxygen-Transfer Reactions4.1 General Mechanism of Oxygen Transfer4.2 Epoxidation4.3 Oxidation of Alkynes4.4 Oxidation of Aromatic Alcohols and Phenols4.5 Oxidation of Nitrogen-Containing Compounds4.6 Conversion of Aldehydes into Nitriles4.7 Oxidation of Alcohols and Ethers4.8 Oxidation of Sulfur-Containing Compounds4.9 Oxygen-Transfer Reaction with Phosphine, Phosphite, and Phosphinite Compounds5 C–H Activation Reactions5.1 Hydroxylation of Nonactivated Tertiary Saturated Carbon Center5.2 Hydroxylation of Aromatic Carbon Center5.3 α-Hydroxylation of Carbonyl Group5.4 Activation of α-Hydrogens of α-Amino Acids6 Other Uses7 Green Chemistry and Rozen’s Reagent8 Experimental Problems9 Further Applications10 Conclusions

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15

Lee, Kyoung. "p-Hydroxylation reactions catalyzed by naphthalene dioxygenase." FEMS Microbiology Letters 255, no. 2 (February 2006): 316–20. http://dx.doi.org/10.1111/j.1574-6968.2005.00079.x.

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16

Ianelli, S., M. Nardelli, D. Belletti, B. Jamart-Grégoire, S. Mercier-Girardot, and P. Caubère. "Stereochemistry of Hydroxylation Reactions on Polycyclic Pyrans." Acta Crystallographica Section C Crystal Structure Communications 51, no. 9 (September 15, 1995): 1885–89. http://dx.doi.org/10.1107/s0108270195001442.

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17

Koziol, A. E., Ruth C. Palenik, Gus J. Palenik, and Dennis W. Wester. "Structural studies of copper catalyzed hydroxylation reactions." Inorganica Chimica Acta 359, no. 8 (May 2006): 2569–74. http://dx.doi.org/10.1016/j.ica.2006.01.042.

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18

Wong, Siew Hoon, Stephen G. Bell, and James J. De Voss. "P450 catalysed dehydrogenation." Pure and Applied Chemistry 89, no. 6 (June 27, 2017): 841–52. http://dx.doi.org/10.1515/pac-2016-1216.

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Abstract Cytochrome P450s belong to a superfamily of enzymes that catalyse a wide variety of oxidative transformations. Hydroxylation is one the most thoroughly investigated of all identified P450-catalysed reactions whilst dehydrogenation has been relatively much less explored to date. P450-catalysed dehydrogenation is often found to occur with hydroxylation and thus, it was initially suspected to be a stepwise process consisting of hydroxylation and subsequent dehydration to yield the final olefin product. This theory has been proven to be invalid and the olefin was shown to be the direct product of a P450-catalysed reaction. This interesting reaction plays a vital role in the metabolism of xenobiotics and the biosynthesis of endogenous compounds, including a number of steroids. A number of well-known examples of P450 mediated dehydrogenation, including those in the metabolism of valproic acid, capsaicin and 3-methylindole and those in the biosynthesis of plant and fungal sterols are discussed in this review.

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19

Skibiński, Robert, Jakub Trawiński, and Maciej Gawlik. "Characterization of Phase I Hepatic Metabolites of Anti-Premature Ejaculation Drug Dapoxetine by UHPLC-ESI-Q-TOF." Molecules 26, no. 13 (June 22, 2021): 3794. http://dx.doi.org/10.3390/molecules26133794.

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Determination of the metabolism pathway of xenobiotics undergoing the hepatic pass is a crucial aspect in drug development since the presence of toxic biotransformation products may result in significant side effects during the therapy. In this study, the complete hepatic metabolism pathway of dapoxetine established according to the human liver microsome assay with the use of a high-resolution LC–MS system was described. Eleven biotransformation products of dapoxetine, including eight metabolites not reported in the literature so far, were detected and identified. N-dealkylation, hydroxylation, N-oxidation and dearylation were found to be the main metabolic reactions for the investigated xenobiotic. In silico analysis of toxicity revealed that the reaction of didesmethylation may contribute to the increased carcinogenic potential of dapoxetine metabolites. On the other hand, N-oxidation and aromatic hydroxylation biotransformation reactions possibly lead to the formation of mutagenic compounds.

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20

Munir, Widad A., and J. Barrett. "The metabolism of xenobiotic compounds by Hymenolepis diminuta (Cestoda: Cyclophyllidea)." Parasitology 91, no. 1 (August 1985): 145–56. http://dx.doi.org/10.1017/s0031182000056584.

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The hydrolytic, reductive and oxidative enzyme systems involved in the phase I biotrans formation of xenobiotic compounds have been investigated in Hymenolepis diminuta. Adult H. diminuta are able to carry out a range of hydrolytic and reductive reactions, but in common with other helminths oxidative detoxification reactions were absent (oxidative demethylation, aniline hydroxylation, nitrobenzene hydroxylation, biphenyl hydroxylation). These oxidative reactions were readily demonstrated in rat liver. Extracts of H. diminuta hydrolysed nitrophenylphosphates and inorganic pyrophosphate, but not arylsulphates, nor could epoxide hydratase activity be detected. N-Deacetylase activity was present. However, O-deacetylase activity could not be demonstrated, although butyrate and palmitate, but not benzoate, esters were hydrolysed. H. diminuta was capable of hydrolysing a range of a-and β-glycosides, but not β-glucuronides. Extracts of H. diminuta reduced azo-compounds, aldehydes and disulphides, but ketones and aromatic nitro-compounds were not reduced. The phase I detoxification systems of H. diminuta differ considerably from those of its rat host; the results also suggest that, within the cestodes, there may be considerable species variation in detoxification reactions.

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21

Crosby, Samantha V., Izzeldin Y. Ahmed, Laura R. Osborn, Zeyuan Wang, Mary A. Schleiff, William E. Fantegrossi, Swati Nagar, Paul L. Prather, Gunnar Boysen, and Grover P. Miller. "Similar 5F-APINACA Metabolism between CD-1 Mouse and Human Liver Microsomes Involves Different P450 Cytochromes." Metabolites 12, no. 8 (August 22, 2022): 773. http://dx.doi.org/10.3390/metabo12080773.

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In 2019, synthetic cannabinoids accounted for more than one-third of new drugs of abuse worldwide; however, assessment of associated health risks is not ethical for controlled and often illegal substances, making CD-1 mouse exposure studies the gold standard. Interpretation of those findings then depends on the similarity of mouse and human metabolic pathways. Herein, we report the first comparative analysis of steady-state metabolism of N-(1-adamantyl)-1-(5-pentyl)-1H-indazole-3-carboxamide (5F-APINACA/5F-AKB48) in CD-1 mice and humans using hepatic microsomes. Regardless of species, 5F-APINACA metabolism involved highly efficient sequential adamantyl hydroxylation and oxidative defluorination pathways that competed equally. Secondary adamantyl hydroxylation was less efficient for mice. At low 5F-APINACA concentrations, initial rates were comparable between pathways, but at higher concentrations, adamantyl hydroxylations became less significant due to substrate inhibition likely involving an effector site. For humans, CYP3A4 dominated both metabolic pathways with minor contributions from CYP2C8, 2C19, and 2D6. For CD-1 mice, Cyp3a11 and Cyp2c37, Cyp2c50, and Cyp2c54 contributed equally to adamantyl hydroxylation, but Cyp3a11 was more efficient at oxidative defluorination than Cyp2c members. Taken together, the results of our in vitro steady-state study indicate a high conservation of 5F-APINACA metabolism between CD-1 mice and humans, but deviations can occur due to differences in P450s responsible for the associated reactions.

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22

Liu, Yi, Puying Luo, Yang Fu, Tianxin Hao, Xuan Liu, Qiuping Ding, and Yiyuan Peng. "Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives." Beilstein Journal of Organic Chemistry 17 (September 22, 2021): 2462–76. http://dx.doi.org/10.3762/bjoc.17.163.

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Great progress has been made in the tandem annulation of enynes in the past few years. This review only presents the corresponding reactions of 1,3-enyne structural motifs to provide the functionalized pyridine and pyrrole derivatives. The functionalization reactions cover iodination, bromination, trifluoromethylation, azidation, carbonylation, arylation, alkylation, selenylation, sulfenylation, amidation, esterification, and hydroxylation. We also briefly introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles.

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23

Amor, Ilef Limem-Ben, Nidhal Salem, Emmanuel Guedon, Jean-Marc Engasser, Leila Chekir-Ghedrira, and Mohamed Ghoul. "Preliminary Investigation of Naringenin Hydroxylation with Recombinant E. coli Expressing Plant Flavonoid Hydroxylation Gene." Natural Product Communications 5, no. 5 (May 2010): 1934578X1000500. http://dx.doi.org/10.1177/1934578x1000500520.

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Flavonoid hydroxylation is one way to increase the biological activities of these molecules and the number of hydroxyl groups needed for polymerization, esterification, alkylation, glycosylation and acylation reactions. These reactions have been suggested as a promising route to enhance flavonoid solubility and stability. In our preliminary study we hydroxylated naringenin (the first flavonoid core synthesized in plants) with recombinant E. coli harboring flavanone 3 hydroxylase (F3H). We demonstrated that recombinant E. coli harboring the F3H from Petroselinum crispum, can convert naringenin to dihydrokaempferol. The whole cell hydroxylase activity was often influenced by the stability of the plasmid harboring the cloned gene and the biomass yield. When the composition of the growth media became richer the amount of formed product decreased about twofold; the naringenin bioconversion yield in LB media was 70% and decreased to 33% in TB. However, the enrichment of culture media increased the biomass yield nearly threefold in LB media, only 0.5 g/L of bacteria was formed, but in TB there was 1.6 g/L. Thus, LB constitutes the best medium for naringenin bioconversion using the recombinant E. coli harboring the F3H; this allows for maximum bioconversion yield and plasmid stability when compared with the fourth tested culture medium. Consequently, E. coli harboring F3H from Petroselinum crispum can be used to produce flavonoids hydroxylated in position 3 that can serve in additional reactions like polymerization, glycosylation, and acylation,

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24

Cox, Robin A., Kap-Soo Cheon, Sam-Rok Keum, and Erwin Buncel. "Mechanism of the benzidine disproportionation of (arylhydrazo)pyridines. The reactions of 4-(4-chlorophenylazo)pyridine and -hydrazo)pyridine in acid media." Canadian Journal of Chemistry 76, no. 6 (June 1, 1998): 896–906. http://dx.doi.org/10.1139/v98-082.

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A kinetic and product analysis study of the reactions of 4-(4-chlorophenylhydrazo)pyridine (1) and 4-(4-chlorophenylazo)pyridine (2) in acid media is reported. The disproportionation of two moles of 1 in aqueous sulfuric acid gives one mole of the oxidized product 2, and one mole each of the reduced products 4-chloroaniline and 4-aminopyridine. The azo compound 2, a product of the reaction of 1, undergoes a slower hydroxylation reaction in acid media, and this process was also investigated. The first-formed product in the reaction of 2 is probably 4-(4-hydroxyphenylazo)pyridine, the 4-chlorine being displaced. At the low substrate concentrations used for the kinetic measurements both reactions are straightforward, but at the much higher concentrations used for product isolation studies a complex product mixture results, one of the products being a dimer. The complexity is increased because 1 had to be used as its hydrochloride salt for reasons of stability, and the chloride ion can also react with the diprotonated substrates; chloride ion also accumulates in the system as it is displaced from 2 during the hydroxylation. Thus chloride ion competes with bisulfate ion (present in large excess) for the diprotonated substrates. Nevertheless, complete mechanistic schemes accounting for all of the observed products, including the dimer, could be derived and are presented. Values of pK BH2 2+ for 2 and two of the azo products, needed for the kinetic analysis, were measured using the excess acidity equilibrium method. The nucleophile reacting with protonated 2 in the rate-determining step of the hydroxylation was positively identified as being bisulfate ion by an excess acidity analysis. A comparison of the reaction of 1 with the equivalent reactions of two previously studied 4-(arylhydrazo)pyridines, 9 and 10, reveals that the benzidine disproportionation of these molecules is an A1 process with the second protonation being a pre-equilibrium; pK BH2 2+ values for the hydrazo compounds could not be measured as they react too quickly, but they could be determined from the kinetic data, using the excess acidity method. The rate-determining step is a thermally allowed 10-electron electrocyclic process of the diprotonated substrate, giving rise to an intermediate that undergoes fast reaction with a molecule of protonated substrate in a thermally allowed 14-electron electrocyclic process to give the observed products.Key words: azopyridines, benzidine, disproportionation, excess acidity, hydrazopyridines, hydroxylation, mechanism.

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25

Funhoff, Enrico G., Jenny Salzmann, Ulrich Bauer, Bernard Witholt, and Jan B. van Beilen. "Hydroxylation and epoxidation reactions catalyzed by CYP153 enzymes." Enzyme and Microbial Technology 40, no. 4 (March 2007): 806–12. http://dx.doi.org/10.1016/j.enzmictec.2006.06.014.

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26

Fan, Boyi, Baocheng Jiang, Sensen Yan, Bohui Xu, Huilian Huang, and Guangtong Chen. "Anti-Inflammatory 18β-Glycyrrhetinin Acid Derivatives Produced by Biocatalysis." Planta Medica 85, no. 01 (August 7, 2018): 56–61. http://dx.doi.org/10.1055/a-0662-0296.

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AbstractIn this study, the biocatalysis of 18β-glycyrrhetinic acid by two strains of filamentous fungi, namely Rhizopus arrhizus AS 3.2893 and Circinella muscae AS 3.2695, was investigated. Scaled-up biotransformation reactions yielded 14 metabolites. Their structures were established based on extensive nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data analyses, and seven of them are new compounds. The two fungal strains exhibited distinct biocatalytic features. R. arrhizus could catalyze hydroxylation and carbonylation reactions, whereas C. muscae preferred to catalyze hydroxylation and glycosidation reactions. These highly specific reactions are difficult to achieve by chemical synthesis, particularly under mild conditions. Furthermore, we found that most of the metabolites exhibited pronounced inhibitory activities on lipopolysaccharides-induced nitric oxide production in RAW264.7 cells. These biotransformed derivatives of 18β-glycyrrhetinic acid could be potential anti-inflammatory agents.

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Amor, Ilef Limem-Ben, Alain Hehn, Emmanuel Guedon, Kamel Ghedira, Jean-Marc Engasser, Leila Chekir-Ghedrira, and Mohamed Ghoul. "Biotransformation of Naringenin to Eriodictyol by Saccharomyces cerevisiea Functionally Expressing Flavonoid 3′ Hydroxylase." Natural Product Communications 5, no. 12 (December 2010): 1934578X1000501. http://dx.doi.org/10.1177/1934578x1000501211.

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To increase the biological activities of flavonoids and to enhance their stability and solubility by functionalization reactions (polymerization, esterification, alkylation, glycosylation and acylation), an increase in the number of hydroxyl groups in these molecules is needed. Hydroxylation reactions may be achieved using either chemical or enzymatic methods, the latter being more highly specific than the former. In our study, the flavonoid 3′ hydroxylase (F3′H) from Gerbera hybrid, functionally expressed in Saccharomyces cerevisiae, was used to hydroxylate naringenin (the first flavonoid core synthesized in plants). Furthermore, we studied factors that may affect naringenin hydroxylation by recombinant cell-like yeast growth on selective or rich media and plasmid stability. The whole recombinant cells hydroxylated naringenin at position 3′ to give eriodictyol. In a selective media, the yeast failed to grow to high cell densities (maximum 5 g/L), but the plasmid stability was nearly 90 %, and naringenin hydroxylation reached 100 %. In a rich complex media, the biomass reached 10 g/L, but the yield of naringenin hydroxylation reached only 71 %, and the plasmid stability decreased. When yeast functionally expressing F3′H from Gerbera hybrid was used, in a selective media, 200 mg/L of eriodictyol from naringenin was produced.

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Łyczko, Paulina, Anna Panek, and Alina Świzdor. "Highly Regioselective and Stereoselective Biohydroxylations of Oxandrolone." Catalysts 11, no. 1 (December 25, 2020): 16. http://dx.doi.org/10.3390/catal11010016.

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Microbially catalyzed reactions are a powerful and valuable tool for organic synthesis of many compounds with potential biological activity. Herein, we report efficient hydroxylations of the steroidal anabolic-androgenic lactone, oxandrolone, in the cultures of three strains of fungi, Fusarium culmorum, Mortierella isabellina, and Laetiporus sulphureus. These reactions resulted in the production of four metabolites identified as 12β-hydroxyoxandrolone (2), 9α-hydroxyoxandrolone (3), 6α-hydroxyoxandrolone (4), and 15α-hydroxyoxandrolone (5), the latter being a new compound. The high substrate conversion rates and the product yields achieved indicate that these strains offer a new way to generate steroidal hydroxylactones with potential pharmaceutical interest. The structures of the isolated derivatives were characterized on the basis of spectroscopic data. The effect of modification of the A-ring structure of the steroid by the lactone group on the selectivity of hydroxylation in cultures of the tested fungi is also discussed.

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ZHOU, YAN, KAI HU, JUNFENG SHEN, ZHENPING JI, and GONGZHEN CHENG. "ROLE OF SOLVENT IN SLURRY PHASE REACTIONS." Surface Review and Letters 15, no. 06 (December 2008): 805–8. http://dx.doi.org/10.1142/s0218625x08012190.

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There exists an optimal amount of solvent (generally water) that can be added to the slurry phase reaction between solid reactants; the reactivity and efficiency of such reactions are different from those without solvent or those with large amount of solvent. Obviously, the solvent plays a crucial role in the process of the reaction, and it is the key to the understanding of unique reactivity and high efficiency of such slurry phase reactions. The water molecule absorbed on the surface of solid reactants, which is called bound water, has uniquely different properties compared with bulk water. Surface hydroxylation resulting from bound water greatly influences the chemical activity of the surface, which could be playing a role as catalyst or as the initialization point for further reactions, so that the reactants can react easily and fast under a simple reaction condition.

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Isobe, Hiroshi, Satomichi Nishihara, Mitsuo Shoji, Shusuke Yamanaka, Jiro Shimada, Masayuki Hagiwara, and Kizashi Yamaguchi. "Extended Hartree-Fock theory of chemical reactions. VIII. Hydroxylation reactions by P450." International Journal of Quantum Chemistry 108, no. 15 (2008): 2991–3009. http://dx.doi.org/10.1002/qua.21874.

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Jing, Xiao-Ran, Huan Liu, Yao Nie, and Yan Xu. "2-Ketoglutarate-Generated In Vitro Enzymatic Biosystem Facilitates Fe(II)/2-Ketoglutarate-Dependent Dioxygenase-Mediated C–H Bond Oxidation for (2s,3r,4s)-4-Hydroxyisoleucine Synthesis." International Journal of Molecular Sciences 21, no. 15 (July 28, 2020): 5347. http://dx.doi.org/10.3390/ijms21155347.

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Fe(II)/2-ketoglutarate-dependent dioxygenase (Fe(II)/2-KG DO)-mediated hydroxylation is a critical type of C–H bond functionalization for synthesizing hydroxy amino acids used as pharmaceutical raw materials and precursors. However, DO activity requires 2-ketoglutarate (2-KG), lack of which reduces the efficiency of Fe(II)/2-KG DO-mediated hydroxylation. Here, we conducted multi-enzymatic syntheses of hydroxy amino acids. Using (2s,3r,4s)-4-hydroxyisoleucine (4-HIL) as a model product, we coupled regio- and stereo-selective hydroxylation of l-Ile by the dioxygenase IDO with 2-KG generation from readily available l-Glu by l-glutamate oxidase (LGOX) and catalase (CAT). In the one-pot system, H2O2 significantly inhibited IDO activity and elevated Fe2+ concentrations of severely repressed LGOX. A sequential cascade reaction was preferable to a single-step process as CAT in the former system hydrolyzed H2O2. We obtained 465 mM 4-HIL at 93% yield in the two-step system. Moreover, this process facilitated C–H hydroxylation of several hydrophobic aliphatic amino acids to produce hydroxy amino acids, and C–H sulfoxidation of sulfur-containing l-amino acids to yield l-amino acid sulfoxides. Thus, we constructed an efficient cascade reaction to produce 4-HIL by providing prerequisite 2-KG from cheap and plentiful l-Glu and developed a strategy for creating enzymatic systems catalyzing 2-KG-dependent reactions in sustainable bioprocesses that synthesize other functional compounds.

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32

Wei, Danlei, Lianqi Huang, Hanying Liang, Junhua Zou, Wenwen Chen, Can Yang, Yidong Hou, Dandan Zheng, and Jinshui Zhang. "Photocatalytic hydroxylation of benzene to phenol over organosilane-functionalized FeVO4 nanorods." Catalysis Science & Technology 11, no. 17 (2021): 5931–37. http://dx.doi.org/10.1039/d1cy00890k.

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Chandra, Bittu, Kundan K. Singh, and Sayam Sen Gupta. "Selective photocatalytic hydroxylation and epoxidation reactions by an iron complex using water as the oxygen source." Chem. Sci. 8, no. 11 (2017): 7545–51. http://dx.doi.org/10.1039/c7sc02780j.

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Suzuki, Kazuto, Joshua Kyle Stanfield, Osami Shoji, Sota Yanagisawa, Hiroshi Sugimoto, Yoshitsugu Shiro, and Yoshihito Watanabe. "Control of stereoselectivity of benzylic hydroxylation catalysed by wild-type cytochrome P450BM3 using decoy molecules." Catalysis Science & Technology 7, no. 15 (2017): 3332–38. http://dx.doi.org/10.1039/c7cy01130j.

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Chen, Xuwen, Wenyan Hao, and Yunyun Liu. "Copper-catalyzed tandem aryl–halogen hydroxylation and CH2Cl2-based N,O-acetalization toward the synthesis of 2,3-dihydrobenzoxazinones." Organic & Biomolecular Chemistry 15, no. 16 (2017): 3423–26. http://dx.doi.org/10.1039/c7ob00625j.

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SAFARI, NASSER, FARZAD BAHADORAN, MOHAMMAD REZA HOSEINZADEH, and REZA GHIASI. "Cytochrome P-450 model reaction: effects of substitution on the rate of aromatic hydroxylation." Journal of Porphyrins and Phthalocyanines 04, no. 03 (April 2000): 285–91. http://dx.doi.org/10.1002/(sici)1099-1409(200004/05)4:3<285::aid-jpp215>3.0.co;2-r.

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The study of haemin-catalysed oxidation reactions was extended to substituted aromatic rings. Both electron-donating and electron-withdrawing substituents on aromatic rings act as para- and meta-directing agents in the presence of tetrakis(2,6-dichlorophenyl)porphyrin iron(III) chloride as catalyst and m-chloroperbenzoic acid as oxidant. A new kinetic method for measuring relative rates of epoxidation of alkenes and related compounds has been developed; while steric hindrance results in decreasing the rate of hydroxylation, electron-rich and electron-withdrawing substituents were found to increase the rate of hydroxylation. A linear relationship between the logarithm of the relative rate of hydroxylation and σ Hammet is obtained, although electron-donating and electron-withdrawing substituents fit separate lines. Addition of pyridine to haemin was shown to increase the yield of epoxidation but decrease the yield of aromatic hydroxylation.

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Jóźwik, Ilona K., Martin Litzenburger, Yogan Khatri, Alexander Schifrin, Marco Girhard, Vlada Urlacher, Andy-Mark W. H. Thunnissen, and Rita Bernhardt. "Structural insights into oxidation of medium-chain fatty acids and flavanone by myxobacterial cytochrome P450 CYP267B1." Biochemical Journal 475, no. 17 (September 11, 2018): 2801–17. http://dx.doi.org/10.1042/bcj20180402.

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Oxidative biocatalytic reactions performed by cytochrome P450 enzymes (P450s) are of high interest for the chemical and pharmaceutical industries. CYP267B1 is a P450 enzyme from myxobacterium Sorangium cellulosum So ce56 displaying a broad substrate scope. In this work, a search for new substrates was performed, combined with product characterization and a structural analysis of substrate-bound complexes using X-ray crystallography and computational docking. The results demonstrate the ability of CYP267B1 to perform in-chain hydroxylations of medium-chain saturated fatty acids (decanoic acid, dodecanoic acid and tetradecanoic acid) and a regioselective hydroxylation of flavanone. The fatty acids are mono-hydroxylated at different in-chain positions, with decanoic acid displaying the highest regioselectivity towards ω-3 hydroxylation. Flavanone is preferably oxidized to 3-hydroxyflavanone. High-resolution crystal structures of CYP267B1 revealed a very spacious active site pocket, similarly to other P450s capable of converting macrocyclic compounds. The pocket becomes more constricted near to the heme and is closed off from solvent by residues of the F and G helices and the B–C loop. The crystal structure of the tetradecanoic acid-bound complex displays the fatty acid bound near to the heme, but in a nonproductive conformation. Molecular docking allowed modeling of the productive binding modes for the four investigated fatty acids and flavanone, as well as of two substrates identified in a previous study (diclofenac and ibuprofen), explaining the observed product profiles. The obtained structures of CYP267B1 thus serve as a valuable prediction tool for substrate hydroxylations by this highly versatile enzyme and will encourage future selectivity changes by rational protein engineering.

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Uehara, Shotaro, Toru Oshio, Kazuyuki Nakanishi, Etsuko Tomioka, Miyu Suzuki, Takashi Inoue, Yasuhiro Uno, Erika Sasaki, and Hiroshi Yamazaki. "Survey of Drug Oxidation Activities in Hepatic and Intestinal Microsomes of Individual Common Marmosets, a New Nonhuman Primate Animal Model." Current Drug Metabolism 20, no. 2 (April 30, 2019): 103–13. http://dx.doi.org/10.2174/1389200219666181003143312.

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Background: Common marmosets (Callithrix jacchus) are potentially useful nonhuman primate models for preclinical studies. Information for major drug-metabolizing cytochrome P450 (P450) enzymes is now available that supports the use of this primate species as an animal model for drug development. Here, we collect and provide an overview of information on the activities of common marmoset hepatic and intestinal microsomes with respect to 28 typical human P450 probe oxidations. Results: Marmoset P450 2D6/8-dependent R-metoprolol O-demethylation activities in hepatic microsomes were significantly correlated with those of midazolam 1′- and 4-hydroxylations, testosterone 6β-hydroxylation, and progesterone 6β-hydroxylation, which are probe reactions for marmoset P450 3A4/5/90. In marmosets, the oxidation activities of hepatic microsomes and intestinal microsomes were roughly comparable for midazolam and terfenadine. Overall, multiple forms of marmoset P450 enzymes in livers and intestines had generally similar substrate recognition functionalities to those of human and/or cynomolgus monkey P450 enzymes. Conclusion: The marmoset could be a model animal for humans with respect to the first-pass extraction of terfenadine and related substrates. These findings provide a foundation for understanding individual pharmacokinetic and toxicological results in nonhuman primates as preclinical models and will help to further support understanding of the molecular mechanisms of human P450 function.

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Grüber, R., J. Aranda, A. Bellili, I. Tuñón, and E. Dumont. "Free energy profiles for two ubiquitous damaging agents: methylation and hydroxylation of guanine in B-DNA." Physical Chemistry Chemical Physics 19, no. 22 (2017): 14695–701. http://dx.doi.org/10.1039/c6cp07966k.

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40

OHKAWA, HIDEO, YOSHIYASU YABUSAKI, TOSHIYUKI SAKAKI, HIROKO MURAKAMI, and MEGUMI SHIBATA. "Hydroxylation Reactions by Recombinant Yeast Cells Expressing P450 Monooxygenases." Annals of the New York Academy of Sciences 613, no. 1 Enzyme Engine (December 1990): 37–43. http://dx.doi.org/10.1111/j.1749-6632.1990.tb18146.x.

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41

Toy, Patrick H., Martin Newcomb, and Lowell P. Hager. "Hypersensitive Radical Probe Studies of Chloroperoxidase-Catalyzed Hydroxylation Reactions." Chemical Research in Toxicology 11, no. 7 (July 1998): 816–23. http://dx.doi.org/10.1021/tx9800295.

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IANELLI, S., M. NARDELLI, D. BELLETTI, B. JAMART-GREGOIRE, S. MERCIER-GIRARDOT, and P. CAUBERE. "ChemInform Abstract: Stereochemistry of Hydroxylation Reactions on Polycyclic Pyrans." ChemInform 27, no. 4 (August 12, 2010): no. http://dx.doi.org/10.1002/chin.199604041.

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Anito, Dejene Assefa, Tian-Xiong Wang, Hai-Peng Liang, Xuesong Ding, and Bao-Hang Han. "Bis(terpyridine) Ru(iii) complex functionalized porous polycarbazole for visible-light driven chemical reactions." Polymer Chemistry 12, no. 31 (2021): 4557–64. http://dx.doi.org/10.1039/d1py00527h.

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Le, Thien-Kim, Jong Hyun Park, Da Som Choi, Ga-Young Lee, Woo Sung Choi, Ki Jun Jeong, Chan Beum Park, and Chul-Ho Yun. "Solar-driven biocatalytic C-hydroxylation through direct transfer of photoinduced electrons." Green Chemistry 21, no. 3 (2019): 515–25. http://dx.doi.org/10.1039/c8gc02398k.

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Photoactivation of flavins is coupled productively with the direct transfer of photoinduced electrons to P450s to achieve photobiocatalytic C-hydroxylation reactions in the absence of nicotinamide cofactors.

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45

El-Sayed, Ashraf S. A., Hanaa Salah Maamoun, Gamal H. Rabie, Ibrahim Shaker, Bothaina A. Alaidaroos, Mostafa G. Ali, and Amgad M. Rady. "Microbial Tyrosinase: Biochemical, Molecular Properties and Pharmaceutical Applications." Biomedical and Pharmacology Journal 14, no. 3 (September 30, 2021): 1281–95. http://dx.doi.org/10.13005/bpj/2229.

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Tyrosinase is a copper-containing monooxygenase involved in thecatalysis of the hydroxylation and oxidation reaction of monophenols and diphenols, respectively, into O-quinones intermediates. Tyrosinase is mainly involved in melanogenesis via two reactions. Firstly, 3,4-dihydroxyphenylalanine is produced through tyrosine hydroxylation the nit oxidized into dopaquinone, and finally gives melanin. However, dopaquinones can results in neuronal damage and cell death through the excessive production, suggesting that tyrosinase may be implanted in the formation human brain’s neuromelanin and association with Parkinson’s diseases. Thus, down regulating the melanin pigments and its intermediates by inhibiting tyrosinase activity is the major pharmaceutical challenge to prevent hyperpigmentation, in addition to therapy of neuromelanin disorders. Thus, this review has been focused on exploring the biochemical and molecular properties of tyrosinase from different sources and its potential inhibition with different natural and synthetic compounds.

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Holland, Herbert L., Michael J. Chernishenko, Morgan Conn, Anthony Munoz, T. Samuel Manoharan, and Michael A. Zawadski. "Enzymic hydroxylation and sulfoxidation of cyclopropyl compounds by fungal biotransformation." Canadian Journal of Chemistry 68, no. 5 (May 1, 1990): 696–700. http://dx.doi.org/10.1139/v90-107.

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A series of compounds containing a cyclopropyl ring adjacent to the position of oxidation during fungal biotransformation has been prepared and subjected to enzymic oxidation using Mortierellaisabellina or Rhizopusarrhizus. Carbon hydroxylation and sulfoxidation reactions were observed, but in neither case did opening of the cyclopropyl ring occur. Both these reactions were subject to inhibition by carbon monoxide but not by cyanide ion, properties characteristic of cytochrome P-450 dependent mono-oxygenase enzymes. Hydroxylation at a cyclopropyl C—H bond has been studied by the use of phenylcyclopropane and phenylthiirane as substrates for the mono-oxygenase of M. isabellina. The former was not oxidized, but the latter was converted to phenyl glyoxylic acid in moderate yield. Keywords: biotransformation, cyclopropanes, fungi, metabolism.

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Atia, Alaa A., and Masanari Kimura. "Oxidative Hydroxylation of Aryl Boronic Acid Catalyzed by Co-porphyrin Complexes via Blue-Light Irradiation." Catalysts 10, no. 11 (October 30, 2020): 1262. http://dx.doi.org/10.3390/catal10111262.

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Oxidative reactions often require unstable and environmentally harmful oxidants; therefore, the investigation of safer alternatives is urgent. Here, the hydroxylation of aryl boronic acid in the presence of Co-complexes is demonstrated. Tetrakis(4-carboxyphenyl) Co(II)-porphyrin was combined with biodegradable polymers such as chitosan catalyzed hydroxylation of phenyl boronic acids to form phenol derivatives under blue-light irradiation. This catalytic system can be used as an eco-friendly oxidation process that does not release oxidizing agents into the atmosphere.

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Lin, Yen-Ting, and Sam P. de Visser. "Product Distributions of Cytochrome P450 OleTJE with Phenyl-Substituted Fatty Acids: A Computational Study." International Journal of Molecular Sciences 22, no. 13 (July 2, 2021): 7172. http://dx.doi.org/10.3390/ijms22137172.

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There are two types of cytochrome P450 enzymes in nature, namely, the monooxygenases and the peroxygenases. Both enzyme classes participate in substrate biodegradation or biosynthesis reactions in nature, but the P450 monooxygenases use dioxygen, while the peroxygenases take H2O2 in their catalytic cycle instead. By contrast to the P450 monooxygenases, the P450 peroxygenases do not require an external redox partner to deliver electrons during the catalytic cycle, and also no external proton source is needed. Therefore, they are fully self-sufficient, which affords them opportunities in biotechnological applications. One specific P450 peroxygenase, namely, P450 OleTJE, reacts with long-chain linear fatty acids through oxidative decarboxylation to form hydrocarbons and, as such, has been implicated as a suitable source for the biosynthesis of biofuels. Unfortunately, the reactions were shown to produce a considerable amount of side products originating from Cα and Cβ hydroxylation and desaturation. These product distributions were found to be strongly dependent on whether the substrate had substituents on the Cα and/or Cβ atoms. To understand the bifurcation pathways of substrate activation by P450 OleTJE leading to decarboxylation, Cα hydroxylation, Cβ hydroxylation and Cα−Cβ desaturation, we performed a computational study using 3-phenylpropionate and 2-phenylbutyrate as substrates. We set up large cluster models containing the heme, the substrate and the key features of the substrate binding pocket and calculated (using density functional theory) the pathways leading to the four possible products. This work predicts that the two substrates will react with different reaction rates due to accessibility differences of the substrates to the active oxidant, and, as a consequence, these two substrates will also generate different products. This work explains how the substrate binding pocket of P450 OleTJE guides a reaction to a chemoselectivity.

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Shang, Ming, Qian Shao, Shang-Zheng Sun, Yan-Qiao Chen, Hui Xu, Hui-Xiong Dai, and Jin-Quan Yu. "Identification of monodentate oxazoline as a ligand for copper-promoted ortho-C–H hydroxylation and amination." Chemical Science 8, no. 2 (2017): 1469–73. http://dx.doi.org/10.1039/c6sc03383k.

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The use of a weakly coordinating monodentate directing group for copper-mediated ortho-hydroxylation and amination reactions allows for the identification of an external oxazoline ligand as a promoter.

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Liu, Yunyun, Meiying Huang, and Li Wei. "Copper-catalyzed synthesis of benzo[d][1,3]dioxin-4-ones via tandem Ar–halogen bond hydroxylation and dichloromethane-based double Williamson etherification." New Journal of Chemistry 41, no. 12 (2017): 4776–78. http://dx.doi.org/10.1039/c7nj00180k.

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The copper-catalyzed tandem reactions of o-halobenzoic acids, dichloromethane and KOH giving benzo[d][1,3]dioxin-4-ones via tandem Ar–X hydroxylation and double Williamson etherification are reported.

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Journal articles on the topic 'Hydroxylation reactions'

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