126
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Amano K, Leung PSC, Rieger R, Quan C, Wang X, Marik J, Suen YF, Kurth MJ, Nantz MH, Ansari AA, Lam KS, Zeniya M, Matsuura E, Coppel RL, Gershwin ME. Chemical xenobiotics and mitochondrial autoantigens in primary biliary cirrhosis: identification of antibodies against a common environmental, cosmetic, and food additive, 2-octynoic acid. THE JOURNAL OF IMMUNOLOGY 2005; 174:5874-83. [PMID: 15845458 DOI: 10.4049/jimmunol.174.9.5874] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Emerging evidence has suggested environmental factors as causative agents in the pathogenesis of primary biliary cirrhosis (PBC). We have hypothesized that in PBC the lipoyl domain of the immunodominant E2 component of pyruvate dehydrogenase (PDC-E2) is replaced by a chemical xenobiotic mimic, which is sufficient to break self-tolerance. To address this hypothesis, based upon our quantitative structure-activity relationship data, a total of 107 potential xenobiotic mimics were coupled to the lysine residue of the immunodominant 15 amino acid peptide of the PDC-E2 inner lipoyl domain and spotted on microarray slides. Sera from patients with PBC (n = 47), primary sclerosing cholangitis (n = 15), and healthy volunteers (n = 20) were assayed for Ig reactivity. PBC sera were subsequently absorbed with native lipoylated PDC-E2 peptide or a xenobiotically modified PDC-E2 peptide, and the remaining reactivity analyzed. Of the 107 xenobiotics, 33 had a significantly higher IgG reactivity against PBC sera compared with control sera. In addition, 9 of those 33 compounds were more reactive than the native lipoylated peptide. Following absorption, 8 of the 9 compounds demonstrated cross-reactivity with lipoic acid. One compound, 2-octynoic acid, was unique in both its quantitative structure-activity relationship analysis and reactivity. PBC patient sera demonstrated high Ig reactivity against 2-octynoic acid-PDC-E2 peptide. Not only does 2-octynoic acid have the potential to modify PDC-E2 in vivo but importantly it was/is widely used in the environment including perfumes, lipstick, and many common food flavorings.
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127
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Dixon S, Robins L, Elling RA, Liu R, Lam KS, Wilson DK, Kurth MJ. Discovery of selective aldo-keto reductase ligands—an on-bead assay strategy. Bioorg Med Chem Lett 2005; 15:2938-42. [PMID: 15911284 DOI: 10.1016/j.bmcl.2005.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 03/03/2005] [Accepted: 03/03/2005] [Indexed: 11/24/2022]
Abstract
An enzyme labeling and screening strategy for the discovery of ligands selective in binding two structurally similar members of the aldo-keto reductase family of enzymes is reported. The resulting fluorescence microscope data obtained by screening a 74,088 member library led to the identification of selective ligands for aldose reductase (ALR2) and aldehyde reductase (ALR1). Resynthesis results validate the selectivity of these ligands.
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128
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Pedemonte N, Sonawane ND, Taddei A, Hu J, Zegarra-Moran O, Suen YF, Robins LI, Dicus CW, Willenbring D, Nantz MH, Kurth MJ, Galietta LJV, Verkman AS. Phenylglycine and Sulfonamide Correctors of Defective ΔF508 and G551D Cystic Fibrosis Transmembrane Conductance Regulator Chloride-Channel Gating. Mol Pharmacol 2005; 67:1797-807. [PMID: 15722457 DOI: 10.1124/mol.105.010959] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel cause cystic fibrosis. The delta F508 mutation produces defects in channel gating and cellular processing, whereas the G551D mutation produces primarily a gating defect. To identify correctors of gating, 50,000 diverse small molecules were screened at 2.5 microM (with forskolin, 20 microM) by an iodide uptake assay in epithelial cells coexpressing delta F508-CFTR and a fluorescent halide indicator (yellow fluorescent protein-H148Q/I152L) after delta F508-CFTR rescue by 24-h culture at 27 degrees C. Secondary analysis and testing of >1000 structural analogs yielded two novel classes of correctors of defective delta F508-CFTR gating ("potentiators") with nanomolar potency that were active in human delta F508 and G551D cells. The most potent compound of the phenylglycine class, 2-[(2-1H-indol-3-yl-acetyl)-methylamino]-N-(4-isopropylphenyl)-2-phenylacetamide, reversibly activated delta F508-CFTR in the presence of forskolin with K(a) approximately 70 nM and also activated the CFTR gating mutants G551D and G1349D with K(a) values of approximately 1100 and 40 nM, respectively. The most potent sulfonamide, 6-(ethylphenylsulfamoyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid cycloheptylamide, had K(a) approximately 20 nM for activation of delta F508-CFTR. In cell-attached patch-clamp experiments, phenylglycine-01 (PG-01) and sulfonamide-01 (SF-01) increased channel open probability >5-fold by the reduction of interburst closed time. An interesting property of these compounds was their ability to act in synergy with cAMP agonists. Microsome metabolism studies and rat pharmacokinetic analysis suggested significantly more rapid metabolism of PG-01 than SF-03. Phenylglycine and sulfonamide compounds may be useful for monotherapy of cystic fibrosis caused by gating mutants and possibly for a subset of delta F508 subjects with significant delta F508-CFTR plasma-membrane expression.
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Abstract
Claims, by two groups, to have prepared 2,1-benzisoxazole derivatives are corrected to show that the products are indazalones (5). In addition, a simple preparation of 3-oxy-substituted 2H-indazole, by an unrecognized method in the literature, is reported.
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130
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Amano K, Leung PSC, Xu Q, Marik J, Quan C, Kurth MJ, Nantz MH, Ansari AA, Lam KS, Zeniya M, Coppel RL, Gershwin ME. Xenobiotic-induced loss of tolerance in rabbits to the mitochondrial autoantigen of primary biliary cirrhosis is reversible. THE JOURNAL OF IMMUNOLOGY 2004; 172:6444-52. [PMID: 15128836 DOI: 10.4049/jimmunol.172.10.6444] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previous work has demonstrated that immunization of rabbits with the xenobiotic 6-bromohexanoate coupled to BSA breaks tolerance and induces autoantibodies to mitochondria in rabbits. Such immunized rabbits develop high-titer Abs to pyruvate dehydrogenase complex (PDC)-E2, the major autoantigen of primary biliary cirrhosis. In efforts to map the fine specificity of these autoantibodies, rabbits were immunized biweekly with 6-bromohexanoate-BSA and screened for reactivity using a unique xenobiotic-peptide-agarose microarray platform with an emphasis on identifying potential structures that mimic the molecular image formed by the association of lipoic acid with the immunodominant PDC-E2 peptide. Essentially, a total of 23 xenobiotics and lipoic acid were coupled to the 12-mer peptide backbones, PDC, a mutant PDC, and albumin. As expected, we succeeded in breaking tolerance using this small organic molecule coupled to BSA. However, unlike multiple experimental methods of breaking tolerance, we report in this study that, following continued immunization, the rabbits recover tolerance. With repeated immunization, the response to the rPDC-E2 protein increased with a gradual reduction in autoantibodies against the lipoic acid-peptide, i.e., the primary tolerance-breaking autoantigen. Detailed analysis of this system may provide strategies on how to restore tolerance in patients with autoimmune disease.
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MESH Headings
- Animals
- Autoantibodies/biosynthesis
- Autoantibodies/metabolism
- Autoantigens/immunology
- Binding Sites, Antibody
- Binding, Competitive/immunology
- Dihydrolipoyllysine-Residue Acetyltransferase
- Female
- Humans
- Hydrocarbons, Brominated/administration & dosage
- Hydrocarbons, Brominated/immunology
- Hydrocarbons, Brominated/metabolism
- Immunoglobulin G/metabolism
- Liver Cirrhosis, Biliary/enzymology
- Liver Cirrhosis, Biliary/immunology
- Mitochondria, Liver/enzymology
- Mitochondria, Liver/immunology
- Oligonucleotide Array Sequence Analysis
- Oligopeptides/administration & dosage
- Oligopeptides/immunology
- Pyruvate Dehydrogenase Complex/immunology
- Rabbits
- Self Tolerance
- Serum Albumin, Bovine/administration & dosage
- Serum Albumin, Bovine/immunology
- Thioctic Acid/immunology
- Thioctic Acid/metabolism
- Xenobiotics/administration & dosage
- Xenobiotics/immunology
- Xenobiotics/metabolism
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131
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Bruggraber SFA, Leung PSC, Amano K, Quan C, Kurth MJ, Nantz MH, Benson GD, Van de Water J, Luketic V, Roche TE, Ansari AA, Coppel RL, Gershwin ME. Autoreactivity to lipoate and a conjugated form of lipoate in primary biliary cirrhosis. Gastroenterology 2003; 125:1705-13. [PMID: 14724823 DOI: 10.1053/j.gastro.2003.09.034] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Although considerable effort has been directed toward the mapping of peptide epitopes by autoantibodies, the role of nonprotein molecules has been less well studied. The immunodominant autoantigen in primary biliary cirrhosis (PBC), E2 components of pyruvate dehydrogenase complexes (PDC-E2), has a lipoate molecule bonded to the domain to which autoantibodies are directed. METHODS We examined sera from patients with PBC (n = 105), primary sclerosing cholangitis (n = 70), and rheumatoid arthritis (n = 28) as well as healthy volunteers (n = 43) for reactivity against lipoic acid. The lipoic acid hapten specificity of the reactive antibodies in PBC sera was determined following incubation of aliquots of the sera with human serum albumin (HSA), lipoylated HSA (HSA-LA), PDC-E2, lipoylated PDC-E2, polyethylene glycol (PEG), lipoylated PEG, free lipoic acid, and synthetic molecular mimics of lipoic acid. RESULTS Anti-lipoic acid specific antibodies were detected in 81% (79 of 97) of antimitochondrial antibody (AMA)-positive patients with PBC but not in controls. Two previously unreported specificities in AMA-positive sera that recognize free lipoic acid and a carrier-conjugated form of lipoic acid were also identified. CONCLUSIONS We hypothesize that conjugated form(s) of native or xenobiotic lipoic acid mimics contribute to the initiation and perpetuation of autoimmunity by at first breaking self-tolerance and participating in subsequent determinant spreading. The variability in the immunoreactive carrier/lipoate conjugates provides an experimental framework on which potential mechanisms for the breakdown of self-tolerance following exposure to xenobiotics can be investigated. The data have implications for patients taking lipoic acid as a dietary supplement.
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132
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Hwang SH, Olmstead MM, Kurth MJ. Solid-Phase Synthesis of an Isoxazolinopyrrole Library. ACTA ACUST UNITED AC 2003; 6:142-8. [PMID: 14714998 DOI: 10.1021/cc034023w] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A four-step solid-phase synthesis of isoxazolinopyrroles 8 that employs an acid-labile 2-(4-formyl-3-methoxyphenoxy)ethyl polystyrene HL resin 1 is reported. Resin-bound vinyl sulfone 5 is obtained by DIC coupling with acid 4, which was in turn synthesized in solution phase by a regioselective nitrile oxide 1,3-dipolar cycloaddition. The resin-bound pyrrole 7 was synthesized on solid phase by pyrrole annulation with various isocyano derivatives and potassium t-butoxide in which the sulfone alpha-anion generated by Michael addition gives the desired pyrrole through internal condensation followed by a sigmatropic [1,5]-hydrogen shift. The resulting isoxazolinopyrroles 8 were released from resin 7 by 10% TFA in moderate to excellent overall yields from 2-(4-formyl-3-methoxyphenoxy)ethyl polystyrene HL resin 1.
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133
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Selmi C, Balkwill DL, Invernizzi P, Ansari AA, Coppel RL, Podda M, Leung PS, Kenny TP, Van De Water J, Nantz MH, Kurth MJ, Gershwin ME. Patients with primary biliary cirrhosis react against a ubiquitous xenobiotic-metabolizing bacterium. Hepatology 2003; 38:1250-7. [PMID: 14578864 DOI: 10.1053/jhep.2003.50446] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Infectious and environmental agents have been proposed as immunologic triggers for primary biliary cirrhosis (PBC). Recently, a ubiquitous organism that metabolizes organic compounds and estrogens, Novosphingobium aromaticivorans, has been defined. Importantly, 2 bacterial proteins have homology with the E2 component of the pyruvate dehydrogenase complex (PDC-E2). Sera from 97 patients with PBC, 46 first-degree relatives, 10 spouses, and 195 controls were studied for reactivity against N. aromaticivorans and Escherichia coli. The reactivity was defined by absorption, affinity purification, and using monoclonal antibodies to PDC-E2. Stool samples from 20 patients with PBC and 34 controls were analyzed by polymerase chain reaction (PCR) for the presence of N. aromaticivorans. Sera from 100% of anti-PDC-E2 positive (77/77), 33% of anti-BCOADC E2 positive (1/3), and 12% of antimitochondrial antibody (AMA) negative patients with PBC (2/17) reacted with titers up to 10(-6) against two known lipoylated bacterial proteins (47 and 50 kd) from N. aromaticivorans, including patients with early disease. This titer was approximately 100- to 1,000-fold higher than against E. coli and verified by absorption, use of affinity-purified sera, and monoclonal antibody reagents. Moreover, 78 of 80 AMA-positive and 5 of 17 AMA-negative patients with PBC had antibodies against 3 other N. aromaticivorans proteins. In contrast, 0 of 195 control sera reacted against N. aromaticivorans. Approximately 25% of patients and controls had N. aromaticivorans in their fecal specimens. In conclusion, based on protein homology, capacity to metabolize xenobiotics as well as modulate estrogens, its presence in feces, and specific immunologic response, we propose that N. aromaticivorans is a candidate for the induction of PBC.
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134
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Springsteel MF, Galietta LJV, Ma T, By K, Berger GO, Yang H, Dicus CW, Choung W, Quan C, Shelat AA, Guy RK, Verkman AS, Kurth MJ, Nantz MH. Benzoflavone activators of the cystic fibrosis transmembrane conductance regulator: towards a pharmacophore model for the nucleotide-binding domain. Bioorg Med Chem 2003; 11:4113-20. [PMID: 12927873 DOI: 10.1016/s0968-0896(03)00435-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Our previous screen of flavones and related heterocycles for the ability to activate the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel indicated that UCCF-029, a 7,8-benzoflavone, was a potent activator. In the present study, we describe the synthesis and evaluation, using cell-based assays, of a series of benzoflavone analogues to examine structure-activity relationships and to identify compounds having greater potency for activation of both wild type CFTR and a mutant CFTR (G551D-CFTR) that causes cystic fibrosis in some human subjects. Using UCCF-029 as a structural guide, a panel of 77 flavonoid analogues was prepared. Analysis of the panel in FRT cells indicated that benzannulation of the flavone A-ring at the 7,8-position greatly improved compound activity and potency for several flavonoids. Incorporation of a B-ring pyridyl nitrogen either at the 3- or 4-position also elevated CFTR activity, but the influence of this structural modification was not as uniform as the influence of benzannulation. The most potent new analogue, UCCF-339, activated wild-type CFTR with a K(d) of 1.7 microM, which is more active than the previous most potent flavonoid activator of CFTR, apigenin. Several compounds in the benzoflavone panel also activated G551D-CFTR, but none were as active as apigenin. Pharmacophore modeling suggests a common binding mode for the flavones and other known CFTR activators at one of the nucleotide-binding sites, allowing for the rational development of more potent flavone analogues.
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135
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Sammelson RE, Ma T, Galietta LJV, Verkman AS, Kurth MJ. 3-(2-Benzyloxyphenyl)isoxazoles and isoxazolines: synthesis and evaluation as CFTR activators. Bioorg Med Chem Lett 2003; 13:2509-12. [PMID: 12852954 DOI: 10.1016/s0960-894x(03)00482-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel class of activators for chloride conductance in the cystic fibrosis transmembrane conductance regulator (CFTR) protein has been identified. These 3-(2-benzyloxyphenyl)isoxazoles and 3-(2-benzyloxyphenyl)isoxazolines were synthesized employing the 1,3-dipolar cycloaddition of nitrile oxides with various alkene and alkyne dipolarophiles. Utilizing a fluorescence cell-based assay of halide transport, the best compounds increased CFTR-dependent chloride transport with half-maximal stimulation at 20-50 microM.
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136
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Caci E, Folli C, Zegarra-Moran O, Ma T, Springsteel MF, Sammelson RE, Nantz MH, Kurth MJ, Verkman AS, Galietta LJV. CFTR activation in human bronchial epithelial cells by novel benzoflavone and benzimidazolone compounds. Am J Physiol Lung Cell Mol Physiol 2003; 285:L180-8. [PMID: 12651632 DOI: 10.1152/ajplung.00351.2002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Activators of the CFTR Cl- channel may be useful for therapy of cystic fibrosis. Short-circuit current (Isc) measurements were done on human bronchial epithelial cells to characterize the best flavone and benzimidazolone CFTR activators identified by lead-based combinatorial synthesis and high-throughput screening. The 7,8-benzoflavone UCcf-029 was a potent activator of Cl- transport, with activating potency (<1 microM) being much better than other flavones, such as apigenin. The benzimidazolone UCcf-853 gave similar Isc but with lower potency (5-20 microM). In combination, the effect induced by maximal UCcf-029 and UCcf-029, UCcf-853, and apigenin increased strongly with increasing basal CFTR activity: for example, Kd for activation by UCcf-029 decreased from >5 to <0.4 microM with increasing basal Isc from approximately 4 microA/cm2 to approximately 12 microA/cm2. This dependence was confirmed in permeabilized Fischer rat thyroid cells stably expressing CFTR. Our results demonstrate efficacy of novel CFTR activators in bronchial epithelia and provide evidence that activating potency depends on basal CFTR activity.
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137
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Leung PSC, Quan C, Park O, Van de Water J, Kurth MJ, Nantz MH, Ansari AA, Coppel RL, Lam KS, Gershwin ME. Immunization with a xenobiotic 6-bromohexanoate bovine serum albumin conjugate induces antimitochondrial antibodies. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:5326-32. [PMID: 12734383 DOI: 10.4049/jimmunol.170.10.5326] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The E2 subunit of pyruvate dehydrogenase complex (PDC-E2) is the major autoantigen recognized by antimitochondrial Abs (AMA) in primary biliary cirrhosis (PBC). Recently, we replaced the lipoic acid moiety of PDC-E2 with a battery of synthetic structures designed to mimic a xenobiotically modified lipoyl hapten on a 12-aa peptide that was found within the immunodominant autoepitope of PDC-E2 and demonstrated that AMA in PBC reacted against several organic modified mimotopes as well as, or sometimes significantly better than, the native lipoyl domain. Based on this data, we immunized rabbits with one such xenobiotic organic compound, 6-bromohexanoate, coupled to BSA. One hundred percent of immunized rabbits developed AMA that have each and every characteristic of human AMAs with reactivity against PDC-E2, E2 subunit of branched chain 2-oxo-acid dehydrogenase, and E2 subunit of 2-oxoglutarate dehydrogenase complex. The rabbit AMA also inhibited enzymatic function of PDC-E2 and, importantly, binds to peptide sequences not present in the xenobiotic carrier immunogen. In contrast, BSA-immunized controls did not produce such activity. Our observation that animals immunized with a xenobiotic BSA complex produce autoantibodies that react not only with the xenobiotic, but also with mitochondrial autoantigens recognized by autoimmune PBC sera, suggests that environmental xenobiotic agents can be a risk factor for the induction of PBC.
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138
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Price MD, Sui JK, Kurth MJ, Schore NE. Oxazaborolidines as functional monomers: ketone reduction using polymer-supported Corey, Bakshi, and Shibata catalysts. J Org Chem 2002; 67:8086-9. [PMID: 12423136 DOI: 10.1021/jo026132n] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The first two polymer-supported versions of the Corey, Bakshi, and Shibata (CBS) catalyst have been prepared. Functional monomers based structurally upon the original B-methylated catalyst have been used to prepare catalytic polymers containing the CBS moiety bound both in a pendant fashion and in the form of a cross-link. Enantioselective reductions of two prochiral ketones have been carried out using the original catalyst in the solution phase as well as the two solid-state systems. While the pendant-bound system shows reduced stereoselectivity, the cross-linked version affords enantioselectivities almost identical to those of the solution-phase model.
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139
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Price MD, Kurth MJ, Schore NE. Comparison of solid-phase and solution-phase chiral auxiliaries in the alkylation/iodolactonization sequence to gamma-butyrolactones. J Org Chem 2002; 67:7769-73. [PMID: 12398501 DOI: 10.1021/jo0260692] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Five prolinol-based chiral auxilaries have been compared for the stereoselective synthesis of gamma-butyrolactones via the sequence of N-acylation, C(alpha)()-allylation, and iodolactonization under both solution-phase and solid-phase conditions. Comparisons of stereoselectivity of both the C(alpha)()-allylation and iodolactonization processes indicate that incorporation of a non-C(2)-symmetric auxiliary as a polymer cross-link gives results superior to those obtained either in solution or with other non-C(2)-symmetric auxiliaries and comparable to those observed using a polymer-supported pseudo-C(2)-symmetric auxiliary.
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140
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Gong YD, Kim SK, Yoo SE, Kurth MJ. Epimerization in Intramolecular Carbanilide Cyclization to Hydantoins: A Computational Study. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2002. [DOI: 10.1246/bcsj.75.2477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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141
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142
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Huang L, Olmstead MM, Kurth MJ. A CONCISE SYNTHESIS OF CHIRAL 3-HYDROXYMETHYL-5-ISOPROPYL MORPHOLINES FROM VALINOL. ORG PREP PROCED INT 2002. [DOI: 10.1080/00304940209355773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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143
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Fan XD, Hsien YL, Kurth MJ, Krochta JM. Synthesis and characterization of lactose based resorcinol resin. J Appl Polym Sci 2002. [DOI: 10.1002/app.11216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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144
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Hwang SH, Kurth MJ. Versatile "traceless" sulfone linker for SPOS: preparation of isoxazolinopyrrole 2-carboxylates. J Org Chem 2002; 67:6564-7. [PMID: 12201785 DOI: 10.1021/jo016377k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A five-step solid-phase synthesis of isoxazolinopyrrole-2-carboxylates (6) that employs a traceless sulfone linker strategy is reported. Resin-bound diene 4, obtained by acetylation and concomitant beta-elimination of acetate from resin-bound allylic alcohol 3, underwent regioselective 1,3-dipolar cycloadditons with nitrile oxides. Formation of the pyrrole products in a resin-releasing strategy was performed by pyrrole annulation with alkyl isocyanoacetates, which react with the vinyl sulfone moiety to generate the target isoxazolinopyrrole-2-carboxylates (6). Use of this chemistry afforded eight isoxazolinopyrrole-2-carboxylates in 6-24% overall yields from polystyrene/divinylbenzene sulfinate 1.
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145
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Kwon HJ, Smith WC, Scharon AJ, Hwang SH, Kurth MJ, Shen B. C-O bond formation by polyketide synthases. Science 2002; 297:1327-30. [PMID: 12193782 DOI: 10.1126/science.1073175] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Polyketide synthases (PKSs) assemble the polyketide carbon backbone by sequential decarboxylative condensation of acyl coenzyme A (CoA) precursors, and the C-C bond-forming step in this process is catalyzed by the beta-ketoacyl synthase (KS) domain or subunit. Genetic and biochemical characterization of the nonactin biosynthesis gene cluster from Streptomyces griseus revealed two KSs, NonJ and NonK, that are highly homologous to known KSs but catalyze sequential condensation of the acyl CoA substrates by forming C-O rather than C-C bonds. This chemistry can be used in PKS engineering to increase the scope and diversity of polyketide biosynthesis.
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146
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Cheng WC, Liu Y, Wong M, Olmstead MM, Lam KS, Kurth MJ. Stereoselective synthesis of unnatural spiroisoxazolinoproline-based amino acids and derivatives. J Org Chem 2002; 67:5673-7. [PMID: 12153267 DOI: 10.1021/jo025611j] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A route to spiroisoxazolinoproline-based amino acid derivatives is reported in which exo-methyleneprolinate 4 (tert-butyl ester) reacts as a dipolarophile with nitrile oxides to generate spiroisoxazolinoprolinates 7/10/11 in good yields (70-75%) and with ca. 1:4 cis:trans diastereoselectivity. tert-Butyl spiroisoxazolinoprolinates were separable by column chromatography and amenable to scale-up leading to single diastereoisomers of N-Boc and N-Fmoc protected spiroisoxazolinoproline amino acids.
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147
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Cheng WC, Kurth MJ. The sulfone linker in solid-phase synthesis: preparation of 3,5-disubstituted cyclopent-2-enones. J Org Chem 2002; 67:4387-91. [PMID: 12076132 DOI: 10.1021/jo0256843] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The preparation of functionalized 3,5-disubstituted cyclopent-2-enones via a solid-phase sulfone linker strategy is described. Polystyrene/divinylbenzene sulfinate 1 underwent S-alkylation followed by alpha,alpha-dialkylation with cis-1,4-dichloro-2-butene to form polymer-bound 3-phenylsulfonylcyclopentenes 8. Subsequent epoxidation of the cyclopentene moiety in 8 was accomplished by treatment of mCPBA, and the resulting oxirane ring in resin 9 was opened with various nucleophiles, i.e., Grignard and cuprate reagents, azide ion, and amines. To complete the sulfone-based linker strategy, Swern or TPAP oxidation of 10 gave a transient gamma-ketosulfone, which underwent sulfinate elimination, thus cleaving the sulfone linker. Eleven 3,5-disubstituted cyclopent-2-enones (11) were prepared with this five-step process in 18-40% overall yield from solid-phase benzene sulfinate 1.
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Kurth MJ, Brown EG. Double diastereoselection in the iodolactonization of 1,6-heptadiene-4-carboxylic acids. J Am Chem Soc 2002. [DOI: 10.1021/ja00256a045] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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149
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Marco MP, Hammock BD, Kurth MJ. Hapten design and development of an ELISA (enzyme-linked immunosorbent assay) for the detection of the mercapturic acid conjugates of naphthalene. J Org Chem 2002. [DOI: 10.1021/jo00078a039] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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150
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Moon HS, Schore NE, Kurth MJ. A polymer-supported chiral auxiliary applied to the iodolactonization reaction: preparation of .gamma.-butyrolactones. J Org Chem 2002. [DOI: 10.1021/jo00049a003] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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