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Kundu S, Sarkar D. Synthetic Attempts Towards α‐Tocopherol – An Overview. J Heterocycl Chem 2022. [DOI: 10.1002/jhet.4565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Subhradip Kundu
- Organic Synthesis and Molecular Engineering Lab, Department of Chemistry National Institute of Technology Rourkela Odisha India
| | - Debayan Sarkar
- Organic Synthesis and Molecular Engineering Lab, Department of Chemistry National Institute of Technology Rourkela Odisha India
- Department of Chemistry Indian Institute of Technology Indore Madhya Pradesh India
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Kennemur J, Maji R, Scharf MJ, List B. Catalytic Asymmetric Hydroalkoxylation of C-C Multiple Bonds. Chem Rev 2021; 121:14649-14681. [PMID: 34860509 PMCID: PMC8704240 DOI: 10.1021/acs.chemrev.1c00620] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Indexed: 01/30/2023]
Abstract
Asymmetric hydroalkoxylation of alkenes constitutes a redox-neutral and 100% atom-economical strategy toward enantioenriched oxygenated building blocks from readily available starting materials. Despite their great potential, catalytic enantioselective additions of alcohols across a C-C multiple bond are particularly underdeveloped, especially compared to other hydrofunctionalization methods such as hydroamination. However, driven by some recent innovations, e.g., asymmetric MHAT methods, asymmetric photocatalytic methods, and the development of extremely strong chiral Brønsted acids, there has been a gratifying surge of reports in this burgeoning field. The goal of this review is to survey the growing landscape of asymmetric hydroalkoxylation by highlighting exciting new advances, deconstructing mechanistic underpinnings, and drawing insight from related asymmetric hydroacyloxylation and hydration. A deep appreciation of the underlying principles informs an understanding of the various selectivity parameters and activation modes in the realm of asymmetric alkene hydrofunctionalization while simultaneously evoking the outstanding challenges to the field moving forward. Overall, we aim to lay a foundation for cross-fertilization among various catalytic fields and spur further innovation in asymmetric hydroalkoxylations of C-C multiple bonds.
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Affiliation(s)
| | | | - Manuel J. Scharf
- Max-Planck-Institut für
Kohlenforschung, Kaiser Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Benjamin List
- Max-Planck-Institut für
Kohlenforschung, Kaiser Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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Sathish S, Preethy KS, Venkatesh R, Sathishkumar R. Rapid enhancement of α-tocopherol content in Nicotiana benthamiana by transient expression of Arabidopsis thaliana Tocopherol cyclase and Homogentisate phytyl transferase genes. 3 Biotech 2018; 8:485. [PMID: 30498659 DOI: 10.1007/s13205-018-1496-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 11/01/2018] [Indexed: 12/18/2022] Open
Abstract
Agrobacterium-mediated transient gene expression have become a method of choice over stable plant genetic transformation. Tocopherols are a family of vitamin E compounds, which are categorized along with tocotrienols occurring naturally in vegetable oils, nuts and leafy green vegetables. This is the first report involving AtTC and AtHPT transient expression in Nicotiana benthamiana and this system can be used efficiently for large scale production of vitamin E. Agroinfiltration studies were carried out in N.benthamiana for the expression of Arabidopsis thaliana (At) genes encoding homogentisate phytyltransferase (HPT) and tocopherol cyclase (TC) individually and in combination (HPT + TC). The transgene presence was analyzed by reverse transcription PCR, which showed the presence of both the vitamin E biosynthetic pathway genes. The gene expression analysis was carried out by (reverse transcription quantitative real-time polymerase chain reaction) RT-qPCR and α-tocopherol content was quantified using high performance liquid chromatography (HPLC). The relative gene expression analysis by RT-qPCR confirmed an increased expression pattern where TC + HPT combination recorded the highest of 231 fold, followed by TC gene with 186 fold, whereas the HPT gene recorded 178 fold. The α-tocopherol content in leaves expressing HPT, TC, and HPT + TC was increased by 4.2, 5.9 and 11.3 fold, respectively, as compared to the control. These results indicate that the transient expression of HPT and TC genes has enhanced the vitamin E levels and stable expression of both A. thaliana genes could be an efficient strategy to enhance vitamin E biosynthesis in agricultural crop breeding.
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Affiliation(s)
- Sundararajan Sathish
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, 641 046 India
| | - Kuppuraj Sree Preethy
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, 641 046 India
| | - Rajendran Venkatesh
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, 641 046 India
| | - Ramalingam Sathishkumar
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore, 641 046 India
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Tocopherol Cyclases-Substrate Specificity and Phylogenetic Relations. PLoS One 2016; 11:e0159629. [PMID: 27462710 PMCID: PMC4963081 DOI: 10.1371/journal.pone.0159629] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 07/06/2016] [Indexed: 12/18/2022] Open
Abstract
In the present studies, we focused on substrate specificity of tocopherol cyclase, the key enzyme in the biosynthesis of the tocopherols and plastochromanol-8, the main plant lipid antioxidants, with special emphasis on the preference for tocopherols and plastochromanol-8 precursors, taking advantage of the recombinant enzyme originating from Arabidopsis thaliana and isolated plastoglobules, thylakoids and various model systems like micelles and thylakoids. Plastoglobules and triacylglycerol micelles were the most efficient reaction environment for the cyclase. In various investigated systems, synthesis of γ-tocopherol proceeded considerably faster than that of plastochromanol-8, probably mainly due to different localization of the corresponding substrates in the analyzed lipid structures. Moreover, our study was complemented by bioinformatics analysis of the phylogenetic relations of the cyclases and sequence motifs, crucial for the enzyme activity, were proposed. The analysis revealed also a group of tocopherol cyclase-like proteins in a number of heterotrophic bacterial species, with a conserved region common with photosynthetic organisms, that might be engaged in the catalytic activity of both groups of organisms.
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Gálvez-Valdivieso G, Cardeñosa R, Pineda M, Aguilar M. Homogentisate phytyltransferase from the unicellular green alga Chlamydomonas reinhardtii. JOURNAL OF PLANT PHYSIOLOGY 2015; 188:80-88. [PMID: 26454640 DOI: 10.1016/j.jplph.2015.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 07/30/2015] [Accepted: 09/23/2015] [Indexed: 06/05/2023]
Abstract
Homogentisate phytyltransferase (HPT) (EC 2.5.1.-) catalyzes the first committed step of tocopherol biosynthesis in all photosynthetic organisms. This paper presents the molecular characterization and expression analysis of HPT1 gene, and a study on the accumulation of tocopherols under different environmental conditions in the unicellular green alga Chlamydomonas reinhardtii. The Chlamydomonas HPT1 protein conserves all the prenylphosphate- and divalent cation-binding sites that are found in polyprenyltransferases and all the amino acids that are essential for its catalytic activity. Its hydrophobicity profile confirms that HPT is a membrane-bound protein. Chlamydomonas genomic DNA analysis suggests that HPT is encoded by a single gene, HPT1, whose promoter region contains multiple motifs related to regulation by jasmonate, abscisic acid, low temperature and light, and an ATCTA motif presents in genes involved in tocopherol biosynthesis and some photosynthesis-related genes. Expression analysis revealed that HPT1 is strongly regulated by dark and low-temperature. Under the same treatments, α-tocopherol increased in cultures exposed to darkness or heat, whereas γ-tocopherol did it in low temperature. The regulatory expression pattern of HPT1 and the changes of tocopherol abundance support the idea that different tocopherols play specific functions, and suggest a role for γ-tocopherol in the adaptation to growth under low-temperature.
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Affiliation(s)
- Gregorio Gálvez-Valdivieso
- Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Rosa Cardeñosa
- Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain
| | - Manuel Pineda
- Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain
| | - Miguel Aguilar
- Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain
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Kruk J, Szymańska R, Cela J, Munne-Bosch S. Plastochromanol-8: fifty years of research. PHYTOCHEMISTRY 2014; 108:9-16. [PMID: 25308762 DOI: 10.1016/j.phytochem.2014.09.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 09/08/2014] [Accepted: 09/16/2014] [Indexed: 05/21/2023]
Abstract
Plastochromanol-8 (PC-8) is an antioxidant that, together with tocopherols and tocotrienols, belongs to the group of tocochromanols. Plastochromanol-8 has been found to occur in several plant species, including mosses, and lichens. PC-8 is found in seeds, leaves and other organs of higher plants. In leaves, PC-8 is restricted to chloroplasts. The identification of tocopherol cyclase (VTE1) as the key enzyme in the biosynthesis of PC-8 suggests that plastoglobules are the primary site of its biosynthesis. Other enzymes related with PC-8 biosynthesis in plastoglobules include: NDC1 and the ABC1-like kinase ABC1K3. The antioxidant properties of PC-8 are similar to those of other chloroplastic antioxidants in polar solvents but considerably they are enhanced in hydrophobic environments, suggesting that the unsaturated side chain performs some quenching activity. As a result of a non-enzymatic reaction, singlet oxygen can oxidize any of the 8 double bonds in the side chain of PC-8, giving at least eight hydroxy-PC-8 isomers. This review summarizes current evidence of a widespread distribution of PC-8 in photosynthetic organisms, as well as the contribution of PC-8 to the pool of lipid-soluble antioxidants in both leaves and seeds.
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Affiliation(s)
- Jerzy Kruk
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Renata Szymańska
- Department of Medical Physics and Biophysics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Reymonta 19, 30-059 Krakow, Poland
| | - Jana Cela
- Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain
| | - Sergi Munne-Bosch
- Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain.
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Genome-wide association study and pathway-level analysis of tocochromanol levels in maize grain. G3-GENES GENOMES GENETICS 2013; 3:1287-99. [PMID: 23733887 PMCID: PMC3737168 DOI: 10.1534/g3.113.006148] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tocopherols and tocotrienols, collectively known as tocochromanols, are the major lipid-soluble antioxidants in maize (Zea mays L.) grain. Given that individual tocochromanols differ in their degree of vitamin E activity, variation for tocochromanol composition and content in grain from among diverse maize inbred lines has important nutritional and health implications for enhancing the vitamin E and antioxidant contents of maize-derived foods through plant breeding. Toward this end, we conducted a genome-wide association study of six tocochromanol compounds and 14 of their sums, ratios, and proportions with a 281 maize inbred association panel that was genotyped for 591,822 SNP markers. In addition to providing further insight into the association between ZmVTE4 (γ-tocopherol methyltransferase) haplotypes and α-tocopherol content, we also detected a novel association between ZmVTE1 (tocopherol cyclase) and tocotrienol composition. In a pathway-level analysis, we assessed the genetic contribution of 60 a priori candidate genes encoding the core tocochromanol pathway (VTE genes) and reactions for pathways supplying the isoprenoid tail and aromatic head group of tocochromanols. This analysis identified two additional genes, ZmHGGT1 (homogentisate geranylgeranyltransferase) and one prephenate dehydratase parolog (of four in the genome) that also modestly contribute to tocotrienol variation in the panel. Collectively, our results provide the most favorable ZmVTE4 haplotype and suggest three new gene targets for increasing vitamin E and antioxidant levels through marker-assisted selection.
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Eggersdorfer M, Laudert D, Létinois U, McClymont T, Medlock J, Netscher T, Bonrath W. Einhundert Jahre Vitamine - eine naturwissenschaftliche Erfolgsgeschichte. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205886] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Eggersdorfer M, Laudert D, Létinois U, McClymont T, Medlock J, Netscher T, Bonrath W. One Hundred Years of Vitamins-A Success Story of the Natural Sciences. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/anie.201205886] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Gálvez-Valdivieso G, Cardeñosa R, Vera JM, Pineda M, Aguilar M. γ-Tocopherol methyltransferase from the green alga Chlamydomonas reinhardtii: functional characterization and expression analysis. PHYSIOLOGIA PLANTARUM 2011; 143:316-328. [PMID: 21883249 DOI: 10.1111/j.1399-3054.2011.01507.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
γ-Tocopherol methyltransferase (γ-TMT) (EC 2.1.1.95) is a very important enzyme in tocopherol biosynthesis in all photosynthetic organisms. In this paper, we present the functional characterization and expression analysis of γ-TMT from the unicellular green alga Chlamydomonas reinhardtii. Recombinant TMT1 enzyme was purified and characterized. The size of TMT1 subunit was estimated as 37 kDa by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), in accordance with the predicted molecular size after TMT1 cDNA sequence. Recombinant TMT1 also showed an apparent molecular mass of 37 kDa in its native conformation, suggesting that native TMT1 has a monomeric structure similar to the plant TMTs already characterized. pH and temperature dependence of TMT1 activity were also similar to plant TMTs. Substrate specificity studies showed that Chlamydomonas TMT1 is responsible for the conversion of γ- and δ-tocopherol to α- and β-tocopherol, respectively. The kinetic properties of Chlamydomonas recombinant γ-TMT activity were studied and γ-TMT1 has a similar affinity for γ- and δ-tocopherol. Promoter sequence analysis and expression analysis by northern blot revealed that tmt1 expression is strongly upregulated by high light and downregulated by low temperature. This regulatory pattern of tmt1 expression supports the idea that γ- and α-tocopherol play specific roles in the adaptation to growth under low temperature and high light stress conditions.
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Affiliation(s)
- Gregorio Gálvez-Valdivieso
- Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología, Campus de Rabanales, Edif. C-4, 3a Planta, Universidad de Córdoba, 14071 Córdoba, Spain
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Mène-Saffrané L, Jones AD, DellaPenna D. Plastochromanol-8 and tocopherols are essential lipid-soluble antioxidants during seed desiccation and quiescence in Arabidopsis. Proc Natl Acad Sci U S A 2010; 107:17815-20. [PMID: 20837525 PMCID: PMC2955118 DOI: 10.1073/pnas.1006971107] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Given their essential role as vitamin E, tocopherols and tocotrienols have been studied extensively in animals and plants. In contrast, our understanding of the function of plastochromanol-8 (PC-8), a third type of tocochromanol with a longer side chain, is very limited despite the wide distribution of PC-8 in the plant kingdom, including species consumed by humans. To investigate PC-8 function in vivo, we combined the Arabidopsis vte1 mutation that eliminates tocopherols and PC-8 and causes the accumulation of 2,3-dimethyl-6-phytyl-1,4-benzoquinol (DMPBQ), a redox-active tocopherol precursor, and the vte2 mutation that eliminates tocopherols without affecting PC-8. The vte2 vte1 double mutant lacks tocopherols, PC-8, and DMPBQ, and exhibits the most severe physiological and biochemical phenotypes of any tocochromanol-affected genotype isolated to date, most notably a severe seedling developmental phenotype associated with massive lipid oxidation initiated during seed desiccation and amplified during seed quiescence. In contrast, the presence of PC-8 in vte2 suppresses or attenuates all of the developmental and biochemical phenotypes observed in vte2 vte1, demonstrating that PC-8 is a lipid antioxidant in vivo. Finally, the low relative fitness of vte2 vte1 demonstrates that tocopherols and PC-8 are in vivo lipid antioxidants essential for seed plant survival.
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Affiliation(s)
| | - A. Daniel Jones
- Departments of Biochemistry and Molecular Biology and
- Chemistry, Michigan State University, East Lansing, MI 48824
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Peuthert A, Pflugmacher S. Influence of the cyanotoxin microcystin-LR on tocopherol in Alfalfa seedlings (Medicago sativa). Toxicon 2010; 56:411-7. [PMID: 20398686 DOI: 10.1016/j.toxicon.2010.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 03/26/2010] [Accepted: 04/07/2010] [Indexed: 10/19/2022]
Abstract
Spray irrigation of crop plants can represent a risk if the water is contaminated with cyanotoxins. These secondary metabolites produced by many cyanobacteria can have adverse effects on organisms, among others the induction of excess oxygen radicals, so-called oxidative stress. Thereby tocopherol as a lipid antioxidant is essential to maintain membrane integrity. In this study the effects of the cyanotoxin microcystin-LR (MC-LR), and a Microcystis crude extract (Mic-CE) containing MC-LR on tocopherol content and gene expression of Homogentisate phytyltransferase (HPT), involved in tocopherol synthesis, were investigated in seedlings of the crop plant Medicago sativa. Exposures to environmental relevant concentrations showed that Mic-CE affects the tocopherols at a lower concentration than the pure toxin. Changes during a 3-day exposure using 0.5mug L(-1) MC-LR and Mic-CE revealed strong increases of alpha- and beta-tocopherol content, whereas the influence on beta-tocopherol was far stronger than on alpha-tocopherol. The HPT mRNA was elevated after 24 and 72h exposure to MC-LR. These results show that also low concentrations of cyanobacterial toxins in the water have strong influence on tocopherol in M. sativa seedlings and therefore represent a stress for the plants.
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Affiliation(s)
- Anja Peuthert
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Department of Aquaculture and Ecophysiology, Müggelseedamm 301, 12587 Berlin, Germany
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Batista JM, López SN, Da Silva Mota J, Vanzolini KL, Cass QB, Rinaldo D, Vilegas W, Da Silva Bolzani V, Kato MJ, Furlan M. Resolution and absolute configuration assignment of a natural racemic chromane fromPeperomia obtusifolia(Piperaceae). Chirality 2009; 21:799-801. [DOI: 10.1002/chir.20676] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Chapelat J, Chougnet A, Woggon WD. Biomimetic Chromanol Cyclisation: A Common Route to α-Tocotrienol and α-Tocopherol. European J Org Chem 2009. [DOI: 10.1002/ejoc.200900019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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A chemical biosynthesis design for an antiatherosclerosis drug by acyclic tocopherol intermediate analogue based on "isoprenomics". ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009. [PMID: 19227458 DOI: 10.1007/978-0-387-85998-9_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Phytyl quinols, namely acyclic tocopherols, are key intermediates of tocopherol biosynthesis, but their biological activities remain unclear. We therefore investigated the structure-activity relationship of phytyl quinols to apply a chemical biosynthesis design for an antiatherosclerosis drug based on isoprenomics. We have achieved the biosynthesis-oriented design and synthesis of alpha- (TX-2254) and beta-(TX-2247) phytyl quinol as an unnatural intermediate, other gamma- (TX-2242) and delta-(TX-2231) phytyl quinol as a natural one. Geometry optimization and Molecular orbital (MO) calculation of TX-2254 showed a unique right-angle structure; however, MO energy of TX-2254 and d-alpha-tocopherol were very similar. Radical reactivity of TX-2231 was equal to dl-alpha-tocopherol, whereas TX-2254, TX-2247, and TX-2231 showed lower reactivity than dl-alpha-tocopherol. All four phytyl quinols showed almost the same moderate inhibitory activity against low-density lipoprotein (LDL) oxidation instead of their different degree of C-methylation with character different from tocopherols. In vivo toxicities of phytyl quinols against chick embryo chorioallantoic membrane (CAM) vasculature were hardly observed. We proposed phytyl quinols were possible antioxidants in plants and animals, like vitamin E.
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Chapelat J, Buss A, Chougnet A, Woggon WD. Diastereoselective Synthesis of α-Tocopherol: A New Concept for the Formation of Chromanols. Org Lett 2008; 10:5123-6. [DOI: 10.1021/ol8019583] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Julien Chapelat
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
| | - Axel Buss
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
| | - Antoinette Chougnet
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
| | - Wolf-D. Woggon
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
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Gille L, Rosenau T, Kozlov A, Gregor W. Ubiquinone and tocopherol: Dissimilar siblings. Biochem Pharmacol 2008; 76:289-302. [DOI: 10.1016/j.bcp.2008.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/06/2008] [Accepted: 04/10/2008] [Indexed: 11/17/2022]
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Kobayashi N, DellaPenna D. Tocopherol metabolism, oxidation and recycling under high light stress in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:607-18. [PMID: 18452591 DOI: 10.1111/j.1365-313x.2008.03539.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Tocopherols are synthesized and accumulated by all plants and many cyanobacteria. The quenching and scavenging of reactive oxygen species and lipid peroxy radicals by tocopherols can result in the formation of various tocopherol oxidation compounds. A targeted GC/MS profiling method was developed to quantify all tocopherols and pathway intermediates, and 23 potential alpha- and gamma-tocopherol oxidation products. This method was used to study the response of wild-type Arabidopsis (Col) and the tocopherol biosynthetic mutants vte1, vte2 and vte4 during 12 h low- and high-light treatments (LL and HL, 90 and 1500 mumol photon m(-2) sec(-1), respectively) and a subsequent 12 h dark recovery period. All tocopherols and pathway intermediates exhibited HL-dependent increases except 2,3-dimethyl-6-phytyl-1,4-benzoquinone (DMPBQ) in vte1 and beta-tocopherol in Col. Profiling of potential tocopherol oxidation products during HL treatment indicated the presence of only alpha-tocopherolquinol (alpha-TQH(2)) in Col and only gamma-tocopherolquinol (gamma-TQH(2)) in vte4, both of which accumulated to similar levels and with similar kinetics the two genotypes. However, during dark recovery, the level of alpha-TQH(2) in Col decreased several times faster than that of gamma-TQH(2) in vte4, suggesting the presence of biochemical processes with higher specificity for alpha-TQH(2). (14)C-labeled alpha-tocopherolquinone (alpha-TQ) applied to isolated Col chloroplasts was converted to (14)C-alpha-tocopherol, demonstrating the existence of a plastid-based system for recycling oxidized alpha-tocopherol. The accumulation of (14)C-trimethylphytylbenzoquinone (TMPBQ) by isolated vte1 plastids treated with (14)C-labeled alpha-TQ is consistent with the tocopherolquinone-recycling pathway utilizing a yet to be identified plastid-localized dehydratase that converts tocopherolquinone to TMPBQ.
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Affiliation(s)
- Naoko Kobayashi
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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Grütter C, Alonso E, Chougnet A, Woggon WD. A biomimetic chromanol cyclization leading to alpha-tocopherol. Angew Chem Int Ed Engl 2007; 45:1126-30. [PMID: 16447150 DOI: 10.1002/anie.200503123] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Christian Grütter
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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Netscher T, Malaisé G, Bonrath W, Breuninger M. A new route to Vitamin E key-intermediates by olefin cross-metathesis. Catal Today 2007. [DOI: 10.1016/j.cattod.2006.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Hunter SC, Cahoon EB. Enhancing vitamin E in oilseeds: unraveling tocopherol and tocotrienol biosynthesis. Lipids 2007; 42:97-108. [PMID: 17393215 DOI: 10.1007/s11745-007-3028-6] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Accepted: 01/17/2007] [Indexed: 11/24/2022]
Abstract
Naturally occurring vitamin E, comprised of four forms each of tocopherols and tocotrienols, are synthesized solely by photosynthetic organisms and function primarily as antioxidants. These different forms vary in their biological availability and in their physiological and chemical activities. Tocopherols and tocotrienols play important roles in the oxidative stability of vegetable oils and in the nutritional quality of crop plants for human and livestock diets. The isolation of genes for nearly all the steps in tocopherol and tocotrienol biosynthesis has facilitated efforts to alter metabolic flux through these pathways in plant cells. Herein we review the recent work done in the field, focusing on branch points and metabolic engineering to enhance and alter vitamin E content and composition in oilseed crops.
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Affiliation(s)
- Sarah C Hunter
- United States Department of Agriculture, ARS, Plant Genetics Research Unit, Donald Danforth Plant Science Center, 975 North Warson Road, Saint Louis, MO 63132, USA.
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Abstract
Vitamin E compounds are biologically essential fat-soluble antioxidants derived from 6-chromanol. This chapter covers the representative literature on the preparation of various stereoisomeric forms and homologues of tocopherols and tocotrienols, and of respective starting materials and intermediates. The industrially most relevant (all-rac)-alpha-tocopherol is generally built up by coupling of arenes with aliphatic precursors. For the synthesis of optically active vitamin E components, various strategies are compiled. In approaches to chiral chroman and side chain building blocks, a broad variety of methods from the repertoire of asymmetric synthesis were applied, that is optical resolution and use of chiral pool starting materials and chiral auxiliaries in stoichiometric as well as catalytic amounts, including catalysis by metal complexes, microorganisms, and enzymes. Most efforts were directed to (2R,4'R,8'R)-alpha-tocopherol due to its prominent biological activity. Syntheses of different stereoisomers (and mixtures thereof) and (beta-, gamma-, delta-) homologues of tocopherols and tocotrienols, as well as methods for their interconversion, are also described.
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Affiliation(s)
- Thomas Netscher
- Research and Development, DSM Nutritional Products CH-4002 Basel, Switzerland
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24
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Netscher T. Preparation of trialkyl-substituted olefins by ruthenium catalyzed cross-metathesis. J Organomet Chem 2006. [DOI: 10.1016/j.jorganchem.2006.09.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chen S, Li H, Liu G. Progress of vitamin E metabolic engineering in plants. Transgenic Res 2006; 15:655-65. [PMID: 17072565 DOI: 10.1007/s11248-006-9012-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 05/10/2006] [Indexed: 01/12/2023]
Abstract
Vitamin E is important for human and animal health. Many human diseases, such as certain cancers and neurodegenerative and cardiovascular disease, are associated with the insufficient intake of vitamin E. The daily requirements for vitamin E in men and women have been increased to 15-30 mg. Because the primary source of dietary vitamin E comes from plants, there is a need to increase vitamin E production through plant engineering in order to meet the demand in human consumption. Numerous studies have been carried out in this field, leading to many successful examples. In this review, we summarized the recent progress in vitamin E metabolic engineering in plants aimed at improving the vitamin E content and regulating composition of vitamin E.
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Affiliation(s)
- Shuangyan Chen
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, PR China
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Malaisé G, Bonrath W, Breuninger M, Netscher T. A New Route to Vitamin E Key-Intermediates by Olefin Cross-Metathesis. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690072] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Grütter C, Alonso E, Chougnet A, Woggon WD. A Biomimetic Chromanol Cyclization Leading to α-Tocopherol. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503123] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Shintani DK. Engineering plants for increased nutrition and antioxidant content through the manipulation of the vitamin E pathway. GENETIC ENGINEERING 2006; 27:231-42. [PMID: 16382879 DOI: 10.1007/0-387-25856-6_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- David K Shintani
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
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Kumar R, Raclaru M, Schüsseler T, Gruber J, Sadre R, Lühs W, Zarhloul KM, Friedt W, Enders D, Frentzen M, Weier D. Characterisation of plant tocopherol cyclases and their overexpression in transgenic Brassica napus seeds. FEBS Lett 2005; 579:1357-64. [PMID: 15733841 DOI: 10.1016/j.febslet.2005.01.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Revised: 01/17/2005] [Accepted: 01/18/2005] [Indexed: 10/25/2022]
Abstract
Tocopherols, collectively known as vitamin E, are only synthesised in photosynthetic organisms. Tocopherol cyclase (TC) catalyses the formation of the chromanol headgroup of the various tocopherol isoforms. TCs from Arabidopsis and maize (Zea mays) were expressed in Escherichia coli and purified. Analysis of the enzymatic properties revealed similarities but also differences between the two enzymes. Overexpression of chimeric TC gene constructs in developing seeds of transgenic rapeseed plants enhanced and modified the relative abundance of individual tocochromanol species in the seed oil, indicating a regulatory function of the enzyme in prenyllipid metabolism.
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Affiliation(s)
- Rajeev Kumar
- RWTH Aachen University, Institute for Biology I-Botany, Worringerweg 1, 52074 Aachen, Germany
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Cichewicz RH, Kenyon VA, Whitman S, Morales NM, Arguello JF, Holman TR, Crews P. Redox Inactivation of Human 15-Lipoxygenase by Marine-Derived Meroditerpenes and Synthetic Chromanes: Archetypes for a Unique Class of Selective and Recyclable Inhibitors. J Am Chem Soc 2004; 126:14910-20. [PMID: 15535718 DOI: 10.1021/ja046082z] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The selective inhibition of human 15-lipoxygenase (15-hLO) could serve as a promising therapeutic target for the prevention of atherosclerosis. A screening of marine sponges revealed that crude extracts of Psammocinia sp. exhibited potent 15-hLO inhibitory activity. Bioassay-guided fractionation led to the isolation of chromarols A-E (8-12) as potent and selective inhibitors of 15-hLO. An additional 22 structurally related compounds, including meroditerpenes from the same Psammocinia sp. (3, 4, 13-16) and our pure compound repository (17, 18), commercially available tocopherols (19-24), and synthetic chromanes (25-32), were evaluated for their ability to inhibit human lipoxygenases. The 6-hydroxychromane moiety found in chromarols A-D was identified as essential for the selective redox inhibition of 15-hLO. Furthermore, the oxidized form of the 6-hydroxychromane could be reduced by ascorbate, suggesting a potential regeneration pathway for these inhibitors in the body. This pharmacophore represents a promising paradigm for the development of a unique class of recyclable 15-hLO redox inhibitors for the treatment of atherosclerosis.
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Affiliation(s)
- Robert H Cichewicz
- Department of Chemistry and Biochemistry and Institute for Marine Sciences, University of California, Santa Cruz, CA 95064, USA
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Collakova E, DellaPenna D. The role of homogentisate phytyltransferase and other tocopherol pathway enzymes in the regulation of tocopherol synthesis during abiotic stress. PLANT PHYSIOLOGY 2003; 133:930-40. [PMID: 14512521 PMCID: PMC219066 DOI: 10.1104/pp.103.026138] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Revised: 06/16/2003] [Accepted: 07/20/2003] [Indexed: 05/18/2023]
Abstract
Tocopherols are amphipathic antioxidants synthesized exclusively by photosynthetic organisms. Tocopherol levels change significantly during plant growth and development and in response to stress, likely as a consequence of the altered expression of pathway-related genes. Homogentisate phytyltransferase (HPT) is a key enzyme limiting tocopherol biosynthesis in unstressed Arabidopsis leaves (E. Collakova, D. DellaPenna [2003] Plant Physiol 131: 632-642). Wild-type and transgenic Arabidopsis plants constitutively overexpressing HPT (35S::HPT1) were subjected to a combination of abiotic stresses for up to 15 d and tocopherol levels, composition, and expression of several tocopherol pathway-related genes were determined. Abiotic stress resulted in an 18- and 8-fold increase in total tocopherol content in wild-type and 35S::HPT1 leaves, respectively, with tocopherol levels in 35S::HPT1 being 2- to 4-fold higher than wild type at all experimental time points. Increased total tocopherol levels correlated with elevated HPT mRNA levels and HPT specific activity in 35S::HPT1 and wild-type leaves, suggesting that HPT activity limits total tocopherol synthesis during abiotic stress. In addition, substrate availability and expression of pathway enzymes before HPT also contribute to increased tocopherol synthesis during stress. The accumulation of high levels of beta-, gamma-, and delta-tocopherols in stressed tissues suggested that the methylation of phytylquinol and tocopherol intermediates limit alpha-tocopherol synthesis. Overexpression of gamma-tocopherol methyltransferase in the 35S::HPT1 background resulted in nearly complete conversion of gamma- and delta-tocopherols to alpha- and beta-tocopherols, respectively, indicating that gamma-tocopherol methyltransferase activity limits alpha-tocopherol synthesis in stressed leaves.
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Affiliation(s)
- Eva Collakova
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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33
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Sattler SE, Cahoon EB, Coughlan SJ, DellaPenna D. Characterization of tocopherol cyclases from higher plants and cyanobacteria. Evolutionary implications for tocopherol synthesis and function. PLANT PHYSIOLOGY 2003; 132:2184-95. [PMID: 12913173 PMCID: PMC181302 DOI: 10.1104/pp.103.024257] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2003] [Revised: 05/02/2003] [Accepted: 05/12/2003] [Indexed: 05/18/2023]
Abstract
Tocopherols are lipophilic antioxidants synthesized exclusively by photosynthetic organisms and collectively constitute vitamin E, an essential nutrient for both humans and animals. Tocopherol cyclase (TC) catalyzes the conversion of various phytyl quinol pathway intermediates to their corresponding tocopherols through the formation of the chromanol ring. Herein, the molecular and biochemical characterization of TCs from Arabidopsis (VTE1 [VITAMIN E 1]), Zea mays (SXD1 [Sucrose Export Deficient 1]) and Synechocystis sp. PCC6803 (slr1737) are described. Mutations in the VTE1, SXD1, or slr1737 genes resulted in both tocopherol deficiency and the accumulation of 2,3-dimethyl-6-phytyl-1,4-benzoquinone (DMPBQ), a TC substrate. Recombinant SXD1 and VTE1 proteins are able to convert DMPBQ to gamma-tocopherol in vitro. In addition, expression of maize SXD1 in a Synechocystis sp. PCC6803 slr1737 knockout mutant restored tocopherol synthesis, indicating that TC activity is evolutionarily conserved between plants and cyanobacteria. Sequence analysis identified a highly conserved 30-amino acid C-terminal domain in plant TCs that is absent from cyanobacterial orthologs. vte1-2 causes a truncation within this C-terminal domain, and the resulting mutant phenotype suggests that this domain is necessary for TC activity in plants. The defective export of Suc in sxd1 suggests that in addition to presumed antioxidant activities, tocopherols or tocopherol breakdown products also function as signal transduction molecules, or, alternatively, the DMPBQ that accumulates in sxd1 disrupts signaling required for efficient Suc export in maize.
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Affiliation(s)
- Scott E Sattler
- Department of Biochemistry and Molecular Biology, Biochemistry Building, Michigan State University, East Lansing, Michigan 48824-1319, USA
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34
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Collakova E, DellaPenna D. Homogentisate phytyltransferase activity is limiting for tocopherol biosynthesis in Arabidopsis. PLANT PHYSIOLOGY 2003; 131:632-42. [PMID: 12586887 PMCID: PMC166839 DOI: 10.1104/pp.015222] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2002] [Revised: 10/16/2002] [Accepted: 11/04/2002] [Indexed: 05/18/2023]
Abstract
Tocopherols are essential components of the human diet and are synthesized exclusively by photosynthetic organisms. These lipophilic antioxidants consist of a chromanol ring and a 15-carbon tail derived from homogentisate (HGA) and phytyl diphosphate, respectively. Condensation of HGA and phytyl diphosphate, the committed step in tocopherol biosynthesis, is catalyzed by HGA phytyltransferase (HPT). To investigate whether HPT activity is limiting for tocopherol synthesis in plants, the gene encoding Arabidopsis HPT, HPT1, was constitutively overexpressed in Arabidopsis. In leaves, HPT1 overexpression resulted in a 10-fold increase in HPT specific activity and a 4.4-fold increase in total tocopherol content relative to wild type. In seeds, HPT1 overexpression resulted in a 4-fold increase in HPT specific activity and a total seed tocopherol content that was 40% higher than wild type, primarily because of an increase in gamma-tocopherol content. This enlarged pool of gamma-tocopherol was almost entirely converted to alpha-tocopherol by crossing HPT1 overexpressing plants with lines constitutively overexpressing gamma-tocopherol methyltransferase. Seed of the resulting double overexpressing lines had a 12-fold increase in vitamin E activity relative to wild type. These results indicate that HPT activity is limiting in various Arabidopsis tissues and that total tocopherol levels and vitamin E activity can be elevated in leaves and seeds by combined overexpression of the HPT1 and gamma-tocopherol methyltransferase genes.
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Affiliation(s)
- Eva Collakova
- Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824, USA
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35
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Shintani DK, Cheng Z, DellaPenna D. The role of 2-methyl-6-phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803. FEBS Lett 2002; 511:1-5. [PMID: 11821038 DOI: 10.1016/s0014-5793(01)03223-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A putative 2-methyl-6-phytylbenzoquinone (MPBQ) methyltransferase gene, SLL0418, was identified from the Synechocystis PCC6803 genome based on its homology to previously characterized gamma-tocopherol methyltransferases. Genetic and biochemical evidence confirmed open reading frame (ORF) SLL0418 encodes a MPBQ methyltransferase. An SLL0418 partial knockout mutant accumulated beta-tocopherol with no effect in the overall tocopherol content of the cell. In vitro assays of the SLL0418 gene expressed in Escherichia coli showed the enzyme efficiently catalyzes methylation of ring carbon 3 of MPBQ. In addition, the enzyme also catalyzes the methylation of ring carbon 3 of 2-methyl-6-solanylbenzoquinol in the terminal step of plastoquinone biosynthesis.
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Affiliation(s)
- David K Shintani
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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36
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Infante JP, Huszagh VA. Impaired arachidonic (20:4n-6) and docosahexaenoic (22:6n-3) acid synthesis by phenylalanine metabolites as etiological factors in the neuropathology of phenylketonuria. Mol Genet Metab 2001; 72:185-98. [PMID: 11243724 DOI: 10.1006/mgme.2001.3148] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The recent literature on polyunsaturated fatty acid metabolism in phenylketonuria (PKU) is critically analyzed. The data suggest that developmental impairment of the accretion of brain arachidonic (20:4n-6) and docosahexaenoic (22:6n-3, DHA) acids is a major etiological factor in the microcephaly and mental retardation of uncontrolled PKU and maternal PKU. These fatty acids appear to be synthesized by the recently elucidated carnitine-dependent, channeled, mitochondrial fatty acid desaturases for which alpha-tocopherolquinone (alpha-TQ) is an essential enzyme cofactor. alpha-TQ can be synthesized either de novo or from alpha-tocopherol. The fetus and newborn would primarily rely on de novo alpha-TQ synthesis for these mitochondrial desaturases because of low maternal transfer of alpha-tocopherol. Homogentisate, a pivotal intermediate in the de novo pathway of alpha-TQ synthesis, is synthesized by 4-hydroxyphenylpyruvate dioxygenase. The major catabolic products of excess phenylalanine, viz. phenylpyruvate and phenyllactate, are proposed to inhibit alpha-TQ synthesis at the level of the dioxygenase reaction by competing with its 4-hydroxyphenylpyruvate substrate, thus leading to a developmental impairment of 20:4n-6 and 22:6n-3 synthesis in uncontrolled PKU and fetuses of PKU mothers. The data suggest that dietary supplementation with carnitine, 20:4n-6, and 22:6n-3 may have therapeutic value for PKU mothers and for PKU patients who have been shown to have a low plasma status of these essential metabolites.
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Affiliation(s)
- J P Infante
- Institute for Theoretical Biochemistry and Molecular Biology, Ithaca, New York 14852, USA.
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37
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Langer P, Eckardt T, Stoll M. Efficient synthesis of butenolide-medium ring ether hybrids by a [3 + 2] cyclization-ring-closing metathesis strategy. Org Lett 2000; 2:2991-3. [PMID: 10986090 DOI: 10.1021/ol006307k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new strategy for the synthesis of bicyclic gamma-alkylidenebutenolides, butenolide-medium ring ether hybrids, is reported which involves Me(3)SiOTf-catalyzed cyclization of 1, 3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride, Mitsunobu reaction, and subsequent ring-closing metathesis.
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Affiliation(s)
- P Langer
- Institut für Organische Chemie der Georg-August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany.
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Grusak MA, DellaPenna D. IMPROVING THE NUTRIENT COMPOSITION OF PLANTS TO ENHANCE HUMAN NUTRITION AND HEALTH. ACTA ACUST UNITED AC 1999; 50:133-161. [PMID: 15012206 DOI: 10.1146/annurev.arplant.50.1.133] [Citation(s) in RCA: 220] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plant foods contain almost all of the mineral and organic nutrients established as essential for human nutrition, as well as a number of unique organic phytochemicals that have been linked to the promotion of good health. Because the concentrations of many of these dietary constituents are often low in edible plant sources, research is under way to understand the physiological, biochemical, and molecular mechanisms that contribute to their transport, synthesis and accumulation in plants. This knowledge can be used to develop strategies with which to manipulate crop plants, and thereby improve their nutritional quality. Improvement strategies will differ between various nutrients, but generalizations can be made for mineral or organic nutrients. This review focuses on the plant nutritional physiology and biochemistry of two essential human nutrients, iron and vitamin E, to provide examples of the type of information that is needed, and the strategies that can be used, to improve the mineral or organic nutrient composition of plants.
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Affiliation(s)
- Michael A. Grusak
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, Houston, Texas 77030; e-mail: , Department of Biochemistry, University of Nevada, Reno, Nevada 89557; e-mail:
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40
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Infante JP. A function for the vitamin E metabolite alpha-tocopherol quinone as an essential enzyme cofactor for the mitochondrial fatty acid desaturases. FEBS Lett 1999; 446:1-5. [PMID: 10100602 DOI: 10.1016/s0014-5793(99)00170-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A critical analysis of the changes in fatty acid patterns and their metabolism elicited by vitamin E deficiency leads to the proposal that a major role of dietary RRR-alpha-tocopherol (alpha-TOC) is as an enzymatic precursor of alpha-tocopherolquinone (alpha-TQ) whose semiquinone radical functions as an essential enzyme cofactor for the fatty acid desaturases of the recently elucidated carnitine-dependent, channeled, mitochondrial desaturation-elongation pathway; a detailed mechanism for its function is proposed. Pathophysiological states produced by vitamin E deficiency and alpha-TOC transfer protein defects, such as ataxia, myopathy, retinopathy, and sterility are proposed to develop from the effects of impaired alpha-TQ-dependent desaturases and the resulting deficiency of their polyenoic fatty acid products.
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Affiliation(s)
- J P Infante
- Institute for Theoretical Biochemistry and Molecular Biology, Ithaca, NY 14852-4512, USA.
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41
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Tietze LF, Schneider G, Wölfling J, Nöbel T, Wulff C, Schubert I, Rübeling A. Effiziente Synthese eines neuartigen Estron‐Talaromycin‐Hybrid‐Naturstoffes. Angew Chem Int Ed Engl 1998. [DOI: 10.1002/(sici)1521-3757(19980918)110:18<2644::aid-ange2644>3.0.co;2-#] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Lutz F. Tietze
- Institut für Organische Chemie der Universität, Tammannstraße 2, D‐37077 Göttingen, Fax: (+49) 551‐399476
| | - Gyula Schneider
- Department of Organic Chemistry, József Attila University, Dom tér 8, H‐6720 Szeged (Ungarn), Fax: (+36) 62‐454276
| | - János Wölfling
- Department of Organic Chemistry, József Attila University, Dom tér 8, H‐6720 Szeged (Ungarn), Fax: (+36) 62‐454276
| | - Thomas Nöbel
- Institut für Organische Chemie der Universität, Tammannstraße 2, D‐37077 Göttingen, Fax: (+49) 551‐399476
| | - Christian Wulff
- Institut für Organische Chemie der Universität, Tammannstraße 2, D‐37077 Göttingen, Fax: (+49) 551‐399476
| | - Ingrid Schubert
- Institut für Organische Chemie der Universität, Tammannstraße 2, D‐37077 Göttingen, Fax: (+49) 551‐399476
| | - Angela Rübeling
- Institut für Organische Chemie der Universität, Tammannstraße 2, D‐37077 Göttingen, Fax: (+49) 551‐399476
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Affiliation(s)
- P M Dewick
- School of Pharmaceutical Sciences, University of Nottingham, UK
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