Co-reporter:Fan Liu, Peter M. Wright, and Andrew G. Myers
Organic Letters 2017 Volume 19(Issue 1) pp:206-209
Publication Date(Web):December 20, 2016
DOI:10.1021/acs.orglett.6b03491
5-Oxatetracyclines were synthesized from d-arabinose using sequential Michael–Claisen cyclization reactions via a 5-oxa-AB enone substrate. The 5-oxatetracyclines were found to have poor stability in aqueous buffer (pH 7.4, 37 °C) and showed little to no inhibition of bacterial growth (S. aureus, E. coli).
Co-reporter:Fan Liu, Andrew G Myers
Current Opinion in Chemical Biology 2016 Volume 32() pp:48-57
Publication Date(Web):June 2016
DOI:10.1016/j.cbpa.2016.03.011
•To date, all tetracycline antibiotics are fermentation products or are derived from them.•A fully synthetic route provides access to tetracyclines of unprecedented structural variability.•Eravacycline and two other clinical candidates are discovered by platform synthetic technology.•Practical manufacture of eravacycline is enabled by a fully synthetic route.Tetracyclines have proven to be safe and effective antibiotics over decades but to date all approved members of the class have been discovered and manufactured by chemical modification of fermentation products, which greatly limits the number of new structures that can be explored as future medicines. This review summarizes research leading to the development of a platform synthetic technology that enabled the discovery of the clinical candidate eravacycline, as well as other promising new tetracycline antibiotics, and provides the basis for a practical route for their manufacture. The approach argues for a reassessment of other antibiotic classes based on natural products for which practical, fully synthetic routes have not yet been developed, suggesting that these may represent underdeveloped resources with great potential to offer safer and more effective anti-infective agents.
Co-reporter:Vibeke Andresen, Bjarte S Erikstein, Herschel Mukherjee, André Sulen, Mihaela Popa, Steinar Sørnes, Håkon Reikvam, Kok-Ping Chan, Randi Hovland, Emmet McCormack, Øystein Bruserud, Andrew G Myers and Bjørn T Gjertsen
Cell Death & Disease 2016 7(12) pp:e2497
Publication Date(Web):2016-12-01
DOI:10.1038/cddis.2016.392
Mutated nucleophosmin 1 (NPM1) acts as a proto-oncogene and is present in ~30% of patients with acute myeloid leukemia (AML). Here we examined the in vitro and in vivo anti-leukemic activity of the NPM1 and chromosome region maintenance 1 homolog (CRM1) interacting natural product avrainvillamide (AVA) and a fully syntetic AVA analog. The NPM1-mutated cell line OCI-AML3 and normal karyotype primary AML cells with NPM1 mutations were significantly more sensitive towards AVA than cells expressing wild-type (wt) NPM1. Furthermore, the presence of wt p53 sensitized cells toward AVA. Cells exhibiting fms-like tyrosine kinase 3 (FLT3) internal tandem duplication mutations also displayed a trend toward increased sensitivity to AVA. AVA treatment induced nuclear retention of the NPM1 mutant protein (NPMc+) in OCI-AML3 cells and primary AML cells, caused proteasomal degradation of NPMc+ and the nuclear export factor CRM1 and downregulated wt FLT3 protein. In addition, both AVA and its analog induced differentiation of OCI-AML3 cells together with an increased phagocytotic activity and oxidative burst potential. Finally, the AVA analog displayed anti-proliferative activity against subcutaneous xenografted HCT-116 and OCI-AML3 cells in mice. Our results demonstrate that AVA displays enhanced potency against defined subsets of AML cells, suggesting that therapeutic intervention employing AVA or related compounds may be feasible.
Co-reporter:Ziyang Zhang;Dr. Takehiro Fukuzaki ;Dr. Andrew G. Myers
Angewandte Chemie 2016 Volume 128( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/ange.201507357
Abstract
D-Desosamine is synthesized in 4 steps from methyl vinyl ketone and sodium nitrite. The key step in this chromatography-free synthesis is the coupling of (R)-4-nitro-2-butanol and glyoxal (trimeric form) mediated by cesium carbonate, which affords in crystalline form 3-nitro-3,4,6-trideoxy-α-D-glucose, a nitro sugar stereochemically homologous to D-desosamine. This strategy has enabled the syntheses of an array of analogous 3-nitro sugars. In each case the 3-nitro sugars are obtained in pure form by crystallization.
Co-reporter:Ziyang Zhang;Dr. Takehiro Fukuzaki ;Dr. Andrew G. Myers
Angewandte Chemie International Edition 2016 Volume 55( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/anie.201507357
Abstract
D-Desosamine is synthesized in 4 steps from methyl vinyl ketone and sodium nitrite. The key step in this chromatography-free synthesis is the coupling of (R)-4-nitro-2-butanol and glyoxal (trimeric form) mediated by cesium carbonate, which affords in crystalline form 3-nitro-3,4,6-trideoxy-α-D-glucose, a nitro sugar stereochemically homologous to D-desosamine. This strategy has enabled the syntheses of an array of analogous 3-nitro sugars. In each case the 3-nitro sugars are obtained in pure form by crystallization.
Co-reporter:Herschel Mukherjee, Kok-Ping Chan, Vibeke Andresen, Mariah L. Hanley, Bjørn Tore Gjertsen, and Andrew G. Myers
ACS Chemical Biology 2015 Volume 10(Issue 3) pp:855
Publication Date(Web):December 19, 2014
DOI:10.1021/cb500872g
Nucleophosmin (NPM1) is a multifunctional phosphoprotein localized predominantly within the nucleoli of eukaryotic cells. Mutations within its C-terminal domain are frequently observed in patients with acute myeloid leukemia (AML), are thought to play a key role in the initiation of the disease, and result in aberrant, cytoplasmic localization of the mutant protein. We have previously shown that the electrophilic antiproliferative natural product (+)-avrainvillamide (1) binds to proteins, including nucleophosmin, by S-alkylation of cysteine residues. Here, we report that avrainvillamide restores nucleolar localization of certain AML-associated mutant forms of NPM1 and provide evidence that this relocalization is mediated by interactions of avrainvillamide with mutant NPM1 and exportin-1 (Crm1). Immunofluorescence and mass spectrometric experiments employing a series of different NPM1 constructs suggest that a specific interaction between avrainvillamide and Cys275 of certain NPM1 mutants mediates the relocalization of these proteins to the nucleolus. Avrainvillamide treatment is also shown to inhibit nuclear export of Crm1 cargo proteins, including AML-associated NPM1 mutants. We also observe that avrainvillamide treatment displaces Thr199-phosphorylated NPM1 from duplicated centrosomes, leads to an accumulation of supernumerary centrosomes, and inhibits dephosphorylation of Thr199-phosphorylated NPM1 by protein phosphatase 1. Avrainvillamide is the first small molecule reported to relocalize specific cytoplasmic AML-associated NPM1 mutants to the nucleolus, providing an important demonstration of principle that small molecule induction of a wild-type NPM1 localization phenotype is feasible in certain human cancer cells.
Co-reporter:Kevin Pröpper, Birger Dittrich, Daniel J. Smaltz, Thomas Magauer, Andrew G. Myers
Bioorganic & Medicinal Chemistry Letters 2014 Volume 24(Issue 18) pp:4410-4413
Publication Date(Web):15 September 2014
DOI:10.1016/j.bmcl.2014.08.016
X-ray crystallographic characterization of products derived from natural and fully synthetic trioxacarcins, molecules with potent antiproliferative effects, illuminates aspects of their reactivity and mechanism of action. Incubation of the fully synthetic trioxacarcin analog 3, which lacks one of the carbohydrate residues present in the natural product trioxacarcin A (1) as well as oxygenation at C2 and C4 yet retains potent antiproliferative effects, with the self-complimentary duplex oligonucleotide d(AACCGGTT) led to production of a crystalline covalent guanine adduct (6). Adduct 6 is closely analogous to gutingimycin (2), the previously reported guanine adduct derived from incubation of natural trioxacarcin A (1) with duplex DNA, suggesting that 3 and 1 likely share a common basis of cytotoxicity. In addition, we isolated a novel, dark-red crystalline guanine adduct (7) from incubation of trioxacarcin A itself with the self-complimentary duplex oligonucleotide d(CGTATACG). Crystallographic analysis suggests that 7 is an anthraquinone derivative, which we propose arises by a sequence of guanosine alkylation within duplex DNA, depurination, base-catalyzed elimination of the trioxacarcinose A carbohydrate residue, and oxidative rearrangement to form an anthraquinone. We believe that this heretofore unrecognized chemical instability of natural trioxacarcins may explain why trioxacarcin analogs lacking C4 oxygenation exhibit superior chemical stabilities yet, as evidenced by structure 3, retain a capacity to form lesions with duplex DNA.
Co-reporter:Dr. Ian B. Seiple;Jaron A. M. Mercer;Robin J. Sussman;Ziyang Zhang ;Dr. Andrew G. Myers
Angewandte Chemie International Edition 2014 Volume 53( Issue 18) pp:4642-4647
Publication Date(Web):
DOI:10.1002/anie.201400928
Abstract
β-Hydroxy-α-amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of β-hydroxy-α-amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one-flask protocol. Enolization of (R,R)- or (S,S)-pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L- or D-threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55–98 %, and are readily transformed into β-hydroxy-α-amino acids by mild hydrolysis or into 2-amino-1,3-diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes.
Co-reporter:Dr. Peter M. Wright;Dr. Ian B. Seiple ;Dr. Andrew G. Myers
Angewandte Chemie International Edition 2014 Volume 53( Issue 34) pp:8840-8869
Publication Date(Web):
DOI:10.1002/anie.201310843
Abstract
The discovery and implementation of antibiotics in the early twentieth century transformed human health and wellbeing. Chemical synthesis enabled the development of the first antibacterial substances, organoarsenicals and sulfa drugs, but these were soon outshone by a host of more powerful and vastly more complex antibiotics from nature: penicillin, streptomycin, tetracycline, and erythromycin, among others. These primary defences are now significantly less effective as an unavoidable consequence of rapid evolution of resistance within pathogenic bacteria, made worse by widespread misuse of antibiotics. For decades medicinal chemists replenished the arsenal of antibiotics by semisynthetic and to a lesser degree fully synthetic routes, but economic factors have led to a subsidence of this effort, which places society on the precipice of a disaster. We believe that the strategic application of modern chemical synthesis to antibacterial drug discovery must play a critical role if a crisis of global proportions is to be averted.
Co-reporter:Dr. Ian B. Seiple;Jaron A. M. Mercer;Robin J. Sussman;Ziyang Zhang ;Dr. Andrew G. Myers
Angewandte Chemie 2014 Volume 126( Issue 18) pp:4730-4735
Publication Date(Web):
DOI:10.1002/ange.201400928
Abstract
β-Hydroxy-α-amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of β-hydroxy-α-amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one-flask protocol. Enolization of (R,R)- or (S,S)-pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L- or D-threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55–98 %, and are readily transformed into β-hydroxy-α-amino acids by mild hydrolysis or into 2-amino-1,3-diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes.
Co-reporter:Dr. Peter M. Wright;Dr. Ian B. Seiple ;Dr. Andrew G. Myers
Angewandte Chemie 2014 Volume 126( Issue 34) pp:8984-9014
Publication Date(Web):
DOI:10.1002/ange.201310843
Abstract
Die Entdeckung und Einführung der Antibiotika im frühen zwanzigsten Jahrhundert hatte gewaltige Auswirkungen auf das Gesundheitwesen. Die chemische Synthese ermöglichte die Entwicklung der ersten antibakteriellen Substanzen, Organoarsenverbindungen und Sulfa-Medikamente, die jedoch bald von wirksameren und weitaus komplexeren natürlichen Antibiotika verdrängt wurden: unter anderem Penicillin, Streptomycin, Tetracyclin und Erythromycin. Diese ersten Abwehrstoffe sind inzwischen – als unvermeidbare Folge der raschen Resistenzentwicklung bei pathogenen Bakterien – deutlich weniger wirksam, was durch die weit verbreitete falsche Anwendung von Antibiotika noch verstärkt wurde. Jahrzehntelang ergänzten Medizinchemiker das Repertoire der Antibiotika durch semisynthetische und in geringerem Maße vollsynthetische Routen, aber ökonomische Faktoren haben einen Rückgang dieser Bemühungen ausgelöst, was die Gesellschaft an den Rand einer Katastrophe führt. Wir sind überzeugt, dass die strategische Anwendung moderner chemischer Synthesemethoden zur Entwicklung antibakterieller Wirkstoffe von entscheidender Bedeutung ist, wenn eine globale Krise abgewendet werden soll.
Co-reporter:Cedric L. Hugelshofer, Kevin T. Mellem, and Andrew G. Myers
Organic Letters 2013 Volume 15(Issue 12) pp:3134-3137
Publication Date(Web):June 7, 2013
DOI:10.1021/ol401337p
The utility of pseudoephenamine as a chiral auxiliary for the alkylative construction of quaternary α-methyl α-amino acids is demonstrated. The method is notable for the high diastereoselectivities of the alkylation reactions, for its versatility with respect to electrophilic substrate partners, and for its mild hydrolysis conditions, which provide α-amino acids without salt contaminants. Alternatively, α-amino esters can be obtained by direct alcoholysis.
Co-reporter:Kevin T. Mellem and Andrew G. Myers
Organic Letters 2013 Volume 15(Issue 21) pp:5594-5597
Publication Date(Web):October 18, 2013
DOI:10.1021/ol402815d
A three-step synthesis of pseudoephenamine suitable for preparing multigram amounts of both enantiomers of the auxiliary from the inexpensive starting material benzil is described. The sequence involves synthesis of the crystalline monomethylimine derivative of benzil, reduction of that substance with lithium aluminum hydride, and resolution of pseudoephenamine with mandelic acid.
Co-reporter:Landy K. Blasdel, DongEun Lee, Binyuan Sun, Andrew G. Myers
Bioorganic & Medicinal Chemistry Letters 2013 23(24) pp: 6905-6910
Publication Date(Web):
DOI:10.1016/j.bmcl.2013.09.066
Co-reporter:Daniel J. Smaltz, Jakub Švenda, and Andrew G. Myers
Organic Letters 2012 Volume 14(Issue 7) pp:1812-1815
Publication Date(Web):March 9, 2012
DOI:10.1021/ol300377a
Two routes to the 2,6-dideoxysugar methyl trioxacarcinoside A are described. Each was enabled by an apparent α-chelation-controlled addition of an allylmetal reagent to a ketone substrate containing a free α-hydroxyl group and a β-hydroxyl substituent, either free or protected as the corresponding di-tert-butylmethyl silyl ether. Both routes provide practical access to gram quantities of trioxacarcinose A in a form suitable for glycosidic coupling reactions.
Co-reporter:Marvin R. Morales;Kevin T. Mellem ; Andrew G. Myers
Angewandte Chemie 2012 Volume 124( Issue 19) pp:4646-4649
Publication Date(Web):
DOI:10.1002/ange.201200370
Co-reporter:Marvin R. Morales;Kevin T. Mellem ; Andrew G. Myers
Angewandte Chemie International Edition 2012 Volume 51( Issue 19) pp:4568-4571
Publication Date(Web):
DOI:10.1002/anie.201200370
Co-reporter:Rebecca L. Simmons ; Robert T. Yu
Journal of the American Chemical Society 2011 Volume 133(Issue 40) pp:15870-15873
Publication Date(Web):September 4, 2011
DOI:10.1021/ja206339s
We show that arylpalladium(II) reagents linked to biotin and indocyanine dye residues can be prepared by decarboxylative palladation of appropriately substituted electron-rich benzoic acid derivatives. When prepared under the conditions described, these organometallic intermediates are tolerant of air and water, can be stored for several months in solution in dimethyl sulfoxide, and permit biotin- and indocyanine dye-labeling of functionally complex olefinic substrates in water by Heck-type coupling reactions.
Co-reporter:David A. Kummer, Derun Li, Amelie Dion and Andrew G. Myers
Chemical Science 2011 vol. 2(Issue 9) pp:1710-1718
Publication Date(Web):07 Jul 2011
DOI:10.1039/C1SC00303H
Here we describe a 5-step sequence to prepare the AB enone 1, the key precursor to fully synthetic tetracyclines, that begins with a diastereoselective Michael–Claisen coupling of two simple starting materials, a cyclohexenone (compound 2 or, in a refinement, a substituted variant, vide infra) and the isoxazole ester 3. This advance defines an 8-step linear sequence to 6-deoxytetracycline antibiotics from three components of similar complexity (cyclohexenone 2, isoxazole ester 3, and structurally diverse D-ring precursors) in which sequential diastereoselective Michael–Claisen cyclization reactions form the A- and C-rings, respectively, of the linearly fused ABCD tetracycline skeleton. In addition to providing a readily scalable, practical route to fully synthetic tetracyclines of broad structural diversity, the sequence reported comprises a series of non-obvious stereoselective transformations, including a novel means for C12a hydroxylation.
Co-reporter:Thomas Magauer and Andrew G. Myers
Organic Letters 2011 Volume 13(Issue 20) pp:5584-5587
Publication Date(Web):September 29, 2011
DOI:10.1021/ol202315m
A 9-step synthetic route to the complex carbohydrate methyl α-trioxacarcinoside B from 2-acetylfuran is described. Anomerically activated forms, including 1-phenylthio, 1-O-(4′-pentenyl), 1-fluoro, and 1-O-acetyl derivatives are also prepared.
Co-reporter:Daniel J. Smaltz and Andrew G. Myers
The Journal of Organic Chemistry 2011 Volume 76(Issue 20) pp:8554-8559
Publication Date(Web):September 7, 2011
DOI:10.1021/jo2016746
An efficient four-step synthetic route to the useful chiral building block (2R,3S)-dihydroxybutyric acid acetonide in >95% ee is detailed. The sequence is readily scaled, requires no chromatography, and allows for efficient recycling of p-phenylbenzyl alcohol, an expedient for enantio- and diastereoenrichment by recrystallization.
Co-reporter:Nicholas Hill;Jakub Švenda
PNAS 2011 Volume 108 (Issue 17 ) pp:6709-6714
Publication Date(Web):2011-04-26
DOI:10.1073/pnas.1015257108
Many first-line cancer drugs are natural products or are derived from them by chemical modification. The trioxacarcins are
an emerging class of molecules of microbial origin with potent antiproliferative effects, which may derive from their ability
to covalently modify duplex DNA. All trioxacarcins appear to be derivatives of a nonglycosylated natural product known as
DC-45-A2. To explore the potential of the trioxacarcins for the development of small-molecule drugs and probes, we have designed
a synthetic strategy toward the trioxacarcin scaffold that enables access to both the natural trioxacarcins and nonnatural
structural variants. Here, we report a synthetic route to DC-45-A2 from a differentially protected precursor, which in turn
is assembled in just six steps from three components of similar structural complexity. The brevity of the sequence arises
from strict adherence to a plan in which strategic bond-pair constructions are staged at or near the end of the synthetic
route.
Co-reporter:Chong Si ; Andrew G. Myers
Angewandte Chemie 2011 Volume 123( Issue 44) pp:10593-10597
Publication Date(Web):
DOI:10.1002/ange.201104769
Co-reporter:Peter M. Wright, Andrew G. Myers
Tetrahedron 2011 67(51) pp: 9853-9869
Publication Date(Web):
DOI:10.1016/j.tet.2011.09.143
Co-reporter:Chong Si ; Andrew G. Myers
Angewandte Chemie International Edition 2011 Volume 50( Issue 44) pp:10409-10413
Publication Date(Web):
DOI:10.1002/anie.201104769
Co-reporter:Jakub Švenda and Andrew G. Myers
Organic Letters 2009 Volume 11(Issue 11) pp:2437-2440
Publication Date(Web):April 27, 2009
DOI:10.1021/ol900665a
Methyl α-methylene-β-tert-butyldimethylsilyloxycarboxylate esters are found to undergo diastereoselective epoxidation in the presence of potassium tert-butoxide−tert-butyl hydroperoxide to form anti products. In an effort to better understand mechanistic details of the transformation and the basis of diastereoselectivities observed, we studied the epoxidation of substrates with α-methylene groups containing (trans) deuterium labels and discovered that oxygen-atom transfer proceeds with ≥95% stereospecificity in all cases examined. These and other experiments suggest that the mechanism of epoxidation is not distinguishable from a concerted process.
Co-reporter:Mark G. Charest;Christian D. Lerner;Jason D. Brubaker;Dionicio R. Siegel
Science 2005 Vol 308(5720) pp:395-398
Publication Date(Web):15 Apr 2005
DOI:10.1126/science.1109755
Abstract
Complex antibiotics based on natural products are almost invariably prepared by semisynthesis, or chemical transformation of the isolated natural products. This approach greatly limits the range of accessible structures that might be studied as new antibiotic candidates. Here we report a short and enantioselective synthetic route to a diverse range of 6-deoxytetracycline antibiotics. The common feature of this class is a scaffold of four linearly fused rings, labeled A through D. We targeted not a single compound but a group of structures with the D ring as a site of structural variability. A late-stage, diastereoselective C-ring construction was used to couple structurally varied D-ring precursors with an AB precursor containing much of the essential functionality for binding to the bacterial ribosome. Five derivatives were synthesized from benzoic acid in yields ranging from 5 to 7% over 14 to 15 steps, and a sixth, (-)-doxycycline, was synthesized in 8.3% yield over 18 steps.
Co-reporter:Andrew M. Haidle
PNAS 2004 101 (33 ) pp:12048-12053
Publication Date(Web):2004-08-17
DOI:10.1073/pnas.0402111101
The cytochalasins are structurally complex natural products with a broad range of apparently unrelated effects in different
biological systems. Different members of the family have variously demonstrated inhibitory activity toward the formation of
actin filaments, toward the functioning of HIV protease, and toward the process of angiogenesis. The structural series is
defined by a largely conserved, rigid bicyclic isoindolone core that is fused to a macrocyclic appendage. The latter structural
component varies widely within the cytochalasins and seems to play an important role in the determination of biological activity.
In this work, we describe the development of a convergent and enantioselective synthetic route to the cytochalasins that allows
for the late-stage introduction of macrocyclic appendages of different sizes and constitutions. We illustrate the route with
the synthesis of the 14-membered macrolactone cytochalasin B (1, an inhibitor of the formation of actin filaments) and the
11-membered macrocarbocyclic cytochalasin L-696,474 (2, an inhibitor of HIV protease) by using common precursors.
Co-reporter:Andrew M. Haidle
PNAS 2004 101 (33 ) pp:12048-12053
Publication Date(Web):2004-08-17
DOI:10.1073/pnas.0402111101
The cytochalasins are structurally complex natural products with a broad range of apparently unrelated effects in different
biological systems. Different members of the family have variously demonstrated inhibitory activity toward the formation of
actin filaments, toward the functioning of HIV protease, and toward the process of angiogenesis. The structural series is
defined by a largely conserved, rigid bicyclic isoindolone core that is fused to a macrocyclic appendage. The latter structural
component varies widely within the cytochalasins and seems to play an important role in the determination of biological activity.
In this work, we describe the development of a convergent and enantioselective synthetic route to the cytochalasins that allows
for the late-stage introduction of macrocyclic appendages of different sizes and constitutions. We illustrate the route with
the synthesis of the 14-membered macrolactone cytochalasin B (1, an inhibitor of the formation of actin filaments) and the
11-membered macrocarbocyclic cytochalasin L-696,474 (2, an inhibitor of HIV protease) by using common precursors.
Co-reporter:Chengguo Xing;Joseph K. Barbay;Jacob R. LaPorte
PNAS 2004 Volume 101 (Issue 16 ) pp:5862-5866
Publication Date(Web):2004-04-20
DOI:10.1073/pnas.0307476101
Saframycin A (SafA) is a member of a class of natural products with potent antiproliferative effects in leukemia- and tumor-derived
cells. This activity is frequently conjectured to derive from the ability of saframycins to covalently modify duplex DNA.
We used a DNA-linked affinity purification technique to identify GAPDH as a protein target of DNA–small molecule adducts of
several members of the saframycin class. Nuclear translocation of GAPDH occurs upon treatment of cancer cells with saframycins,
and depletion of cellular GAPDH levels by small interfering RNA transfection confers drug resistance. Roeder and coworkers
have recently suggested that GAPDH is a key transcriptional coactivator necessary for entry into S phase. Our data suggest
that GAPDH is also capable of forming a ternary complex with saframycin-related compounds and DNA that induces a toxic response
in cells. These studies implicate a previously unknown molecular mechanism of antiproliferative activity and, given that one
member of the saframycin class has shown efficacy in cancer treatment, suggest that GAPDH may be a potential target for chemotherapeutic
intervention.
Co-reporter:Andrew G. Myers ;Philip C. Hogan;Alexer R. Hurd and;Steven D. Goldberg
Angewandte Chemie International Edition 2002 Volume 41(Issue 6) pp:
Publication Date(Web):15 MAR 2002
DOI:10.1002/1521-3773(20020315)41:6<1062::AID-ANIE1062>3.0.CO;2-8
Four components, each prepared in multigram amounts, have been assembled in the convergent (25 steps in the longest linear sequence), enantioselective synthesis of the differentially protected kedarcidin chromophore aglycon (1). In addition to the enantioselective synthesis of each of the four components, the route features a transannular anionic cyclization to form the bicyclo[7.3.0]dodecadienediyne core in the presence of an ansa-bridged macrolactone. MOM=methoxymethyl, TIPS=triisopropylsilyl, TES=triethylsilyl.
Co-reporter:Andrew G. Myers ;Philip C. Hogan;Alexer R. Hurd and;Steven D. Goldberg
Angewandte Chemie 2002 Volume 114(Issue 6) pp:
Publication Date(Web):15 MAR 2002
DOI:10.1002/1521-3757(20020315)114:6<1104::AID-ANGE1104>3.0.CO;2-L
Vier in Grammmengen hergestellte Komponenten wurden verknüpft bei der konvergenten (längste lineare Sequenz: 25 Stufen), enantioselektiven Synthese des komplementär geschützten Aglycons des Kedarcidin-Chromophors (1). Einer der Schlüsselschritte war eine transanulare anionisch induzierte Cyclisierung zum Bicyclo[7.3.0]dodecadiendiin-Gerüst in Gegenwart eines überbrückten Makrolactons. MOM=Methoxymethyl, TIPS=Triisopropylsilyl, TES=Triethylsilyl.
Co-reporter:Scott E. Schaus;Duccio Cavalieri
PNAS 2001 Volume 98 (Issue 20 ) pp:11075-11080
Publication Date(Web):2001-09-25
DOI:10.1073/pnas.191340698
The natural product neocarzinostatin (NCS), a protein–small
molecule complex, exhibits potent antiproliferative activity in
mammalian cells but has little apparent effect on the growth of the
unicellular eukaryotic organism, Saccharomyces
cerevisiae. Here, we show by whole-genome transcription
profiling experiments that incubation of S. cerevisiae
with NCS leads to dramatic and wide-ranging modifications in the
expression profile of yeast genes. Approximately 18% of yeast
transcripts are altered by 2-fold or more within 4 h of treatment
with NCS. Analysis of the observed transcription profile provides
evidence that yeast rapidly and continuously overexpress multiple
DNA-damage repair genes during NCS exposure. Perhaps to meet the
energetic requirements of continuous DNA-damage repair, yeast cells
enter respiration upon prolonged exposure to NCS, although grown in
nutrient-rich medium. The NCS protein component is readily transported
into S. cerevisiae, as demonstrated by fluorescence
microscopy of yeast treated with fluorescently labeled NCS.
Transcription profiling experiments with neocarzinostatin protein alone
implicate a specific resistance mechanism in yeast that targets the NCS
protein component, one involving the nonclassical export pathway. These
experiments provide a detailed picture of the effects of exposure to
NCS upon yeast and the mechanisms they engage as a response to this
protein–small molecule DNA-damaging agent.
Co-reporter:Andrew G. Myers ;Steven D. Goldberg
Angewandte Chemie 2000 Volume 112(Issue 15) pp:
Publication Date(Web):2 AUG 2000
DOI:10.1002/1521-3757(20000804)112:15<2844::AID-ANGE2844>3.0.CO;2-M
Co-reporter:David A. Kummer, Derun Li, Amelie Dion and Andrew G. Myers
Chemical Science (2010-Present) 2011 - vol. 2(Issue 9) pp:NaN1718-1718
Publication Date(Web):2011/07/07
DOI:10.1039/C1SC00303H
Here we describe a 5-step sequence to prepare the AB enone 1, the key precursor to fully synthetic tetracyclines, that begins with a diastereoselective Michael–Claisen coupling of two simple starting materials, a cyclohexenone (compound 2 or, in a refinement, a substituted variant, vide infra) and the isoxazole ester 3. This advance defines an 8-step linear sequence to 6-deoxytetracycline antibiotics from three components of similar complexity (cyclohexenone 2, isoxazole ester 3, and structurally diverse D-ring precursors) in which sequential diastereoselective Michael–Claisen cyclization reactions form the A- and C-rings, respectively, of the linearly fused ABCD tetracycline skeleton. In addition to providing a readily scalable, practical route to fully synthetic tetracyclines of broad structural diversity, the sequence reported comprises a series of non-obvious stereoselective transformations, including a novel means for C12a hydroxylation.