1
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Bradley NP, Wahl KL, Steenwyk JL, Rokas A, Eichman BF. Resistance-Guided Mining of Bacterial Genotoxins Defines a Family of DNA Glycosylases. mBio 2022; 13:e0329721. [PMID: 35311535 PMCID: PMC9040887 DOI: 10.1128/mbio.03297-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 02/22/2022] [Indexed: 11/20/2022] Open
Abstract
Unique DNA repair enzymes that provide self-resistance against therapeutically important, genotoxic natural products have been discovered in bacterial biosynthetic gene clusters (BGCs). Among these, the DNA glycosylase AlkZ is essential for azinomycin B production and belongs to the HTH_42 superfamily of uncharacterized proteins. Despite their widespread existence in antibiotic producers and pathogens, the roles of these proteins in production of other natural products are unknown. Here, we determine the evolutionary relationship and genomic distribution of all HTH_42 proteins from Streptomyces and use a resistance-based genome mining approach to identify homologs associated with known and uncharacterized BGCs. We find that AlkZ-like (AZL) proteins constitute one distinct HTH_42 subfamily and are highly enriched in BGCs and variable in sequence, suggesting each has evolved to protect against a specific secondary metabolite. As a validation of the approach, we show that the AZL protein, HedH4, associated with biosynthesis of the alkylating agent hedamycin, excises hedamycin-DNA adducts with exquisite specificity and provides resistance to the natural product in cells. We also identify a second, phylogenetically and functionally distinct subfamily whose proteins are never associated with BGCs, are highly conserved with respect to sequence and genomic neighborhood, and repair DNA lesions not associated with a particular natural product. This work delineates two related families of DNA repair enzymes-one specific for complex alkyl-DNA lesions and involved in self-resistance to antimicrobials and the other likely involved in protection against an array of genotoxins-and provides a framework for targeted discovery of new genotoxic compounds with therapeutic potential. IMPORTANCE Bacteria are rich sources of secondary metabolites that include DNA-damaging genotoxins with antitumor/antibiotic properties. Although Streptomyces produce a diverse number of therapeutic genotoxins, efforts toward targeted discovery of biosynthetic gene clusters (BGCs) producing DNA-damaging agents is lacking. Moreover, work on toxin-resistance genes has lagged behind our understanding of those involved in natural product synthesis. Here, we identified over 70 uncharacterized BGCs producing potentially novel genotoxins through resistance-based genome mining using the azinomycin B-resistance DNA glycosylase AlkZ. We validate our analysis by characterizing the enzymatic activity and cellular resistance of one AlkZ ortholog in the BGC of hedamycin, a potent DNA alkylating agent. Moreover, we uncover a second, phylogenetically distinct family of proteins related to Escherichia coli YcaQ, a DNA glycosylase capable of unhooking interstrand DNA cross-links, which differs from the AlkZ-like family in sequence, genomic location, proximity to BGCs, and substrate specificity. This work defines two families of DNA glycosylase for specialized repair of complex genotoxic natural products and generalized repair of a broad range of alkyl-DNA adducts and provides a framework for targeted discovery of new compounds with therapeutic potential.
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Affiliation(s)
- Noah P. Bradley
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Katherine L. Wahl
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Jacob L. Steenwyk
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Brandt F. Eichman
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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2
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Li X, Shimaya R, Dairi T, Chang WC, Ogasawara Y. Identification of Cyclopropane Formation in the Biosyntheses of Hormaomycins and Belactosins: Sequential Nitration and Cyclopropanation by Metalloenzymes. Angew Chem Int Ed Engl 2022; 61:e202113189. [PMID: 34904348 PMCID: PMC8810744 DOI: 10.1002/anie.202113189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Indexed: 11/07/2022]
Abstract
Hormaomycins and belactosins are peptide natural products that contain unusual cyclopropane moieties. Bioinformatics analysis of the corresponding biosynthetic gene clusters showed that two conserved genes, hrmI/belK and hrmJ/belL, were potential candidates for catalyzing cyclopropanation. Using in vivo and in vitro assays, the functions of HrmI/BelK and HrmJ/BelL were established. HrmI and BelK, which are heme oxygenase-like dinuclear iron enzymes, catalyze oxidation of the ϵ-amino group of l-lysine to afford l-6-nitronorleucine. Subsequently, HrmJ and BelL, which are iron- and α-ketoglutarate-dependent oxygenases, effectively convert l-6-nitronorleucine into 3-(trans-2-nitrocyclopropyl)-alanine through C4-C6 bond installation. These observations disclose a novel pathway of cyclopropane ring construction and exemplify the new chemistry involving metalloenzymes in natural product biosynthesis.
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Affiliation(s)
- Xiaojun Li
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695 (USA)
| | - Ryo Shimaya
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan)
| | - Tohru Dairi
- Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan)
| | - Wei-chen Chang
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695 (USA)
| | - Yasushi Ogasawara
- Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan)
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3
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Li X, Shimaya R, Dairi T, Chang W, Ogasawara Y. Identification of Cyclopropane Formation in the Biosyntheses of Hormaomycins and Belactosins: Sequential Nitration and Cyclopropanation by Metalloenzymes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202113189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xiaojun Li
- Department of Chemistry North Carolina State University 2620 Yarbrough Drive Raleigh NC 27695 USA
| | - Ryo Shimaya
- Graduate School of Chemical Sciences and Engineering Hokkaido University N13W8, Kita-ku Sapporo Hokkaido 060-8628 Japan
| | - Tohru Dairi
- Graduate School of Engineering Hokkaido University N13W8, Kita-ku Sapporo Hokkaido 060-8628 Japan
| | - Wei‐chen Chang
- Department of Chemistry North Carolina State University 2620 Yarbrough Drive Raleigh NC 27695 USA
| | - Yasushi Ogasawara
- Graduate School of Engineering Hokkaido University N13W8, Kita-ku Sapporo Hokkaido 060-8628 Japan
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4
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Zhang JR, Jin HS, Sun J, Wang J, Zhao LM. Time-Economical Synthesis of Bis-Spiro Cyclopropanes via Cascade 1,6-Conjugate Addition/Dearomatization Reaction of para
-Quinone Methides with 3-Chlorooxindoles. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000830] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jing-Ru Zhang
- School of Chemistry and Materials Science; Jiangsu Normal University; 221116 Xuzhou Jiangsu China
| | - Hai-Shan Jin
- School of Chemistry and Materials Science; Jiangsu Normal University; 221116 Xuzhou Jiangsu China
| | - Jin Sun
- School of Chemistry and Materials Science; Jiangsu Normal University; 221116 Xuzhou Jiangsu China
| | - Jie Wang
- School of Chemistry and Materials Science; Jiangsu Normal University; 221116 Xuzhou Jiangsu China
| | - Li-Ming Zhao
- School of Chemistry and Materials Science; Jiangsu Normal University; 221116 Xuzhou Jiangsu China
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines; Institute of Materia Medica; Chinese Academy of Medical Sciences and Peking Union Medical College; 100050 Beijing China
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5
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Mhetre AB, Sreedhar E, Dubey R, Sable GA, Lee H, Yang H, Lee K, Nam DH, Lim D. Synthesis and biological evaluation of potent benzoselenophene and heteroaromatic analogues of ( S)-1-(chloromethyl)-8-methoxy-2,3-dihydro-1 H-benzo[ e]indol-5-ol ( seco-MCBI). RSC Adv 2019; 9:29023-29036. [PMID: 35528410 PMCID: PMC9071829 DOI: 10.1039/c9ra04749b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 08/29/2019] [Indexed: 11/21/2022] Open
Abstract
A diverse series of compounds (18a-x) were synthesized from (S)-1-(chloromethyl)-8-methoxy-2,3-dihydro-1H-benzo[e]indol-5-ol (seco-MCBI) and benzoselenophene or heteroaromatic acids. These new compounds were evaluated for their cytotoxicity against the human gastric NCI-N87 and human ovarian SK-OV3 cancer cell lines. The incorporation of a methoxy substituent at the C-7 position of the seco-CBI unit enhances the cytotoxicity through its additional van der Waals interaction and gave a much higher potency than the corresponding seco-CBI-based analogues. Similarly, the seco-MCBI-benzoselenophene conjugates (18h-x) exhibited substitution effects on biological activity, and the N-butyramido and N-methylthiopropanamido analogues are highly potent, possessing >77- and >24-fold better activity than seco-MCBI-TMI for the SK-OV3 and NCI-N87 cell lines, respectively.
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Affiliation(s)
- Amol B Mhetre
- Department of Chemistry, Sejong University Seoul 143-747 Republic of Korea
| | | | - Rashmi Dubey
- Department of Chemistry, Sejong University Seoul 143-747 Republic of Korea
| | - Ganesh A Sable
- Department of Chemistry, Sejong University Seoul 143-747 Republic of Korea
| | - Hangeun Lee
- Department of Chemistry, Sejong University Seoul 143-747 Republic of Korea
| | - Heekyoung Yang
- Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul Republic of Korea
| | - Kyoungmin Lee
- Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul Republic of Korea
| | - Do-Hyun Nam
- Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul Republic of Korea
| | - Dongyeol Lim
- Department of Chemistry, Sejong University Seoul 143-747 Republic of Korea
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Zhang J, Shukla V, Boger DL. Inverse Electron Demand Diels-Alder Reactions of Heterocyclic Azadienes, 1-Aza-1,3-Butadienes, Cyclopropenone Ketals, and Related Systems. A Retrospective. J Org Chem 2019; 84:9397-9445. [PMID: 31062977 DOI: 10.1021/acs.joc.9b00834] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A summary of the investigation and applications of the inverse electron demand Diels-Alder reaction is provided that have been conducted in our laboratory over a period that now spans more than 35 years. The work, which continues to provide solutions to complex synthetic challenges, is presented in the context of more than 70 natural product total syntheses in which the reactions served as a key strategic step in the approach. The studies include the development and use of the cycloaddition reactions of heterocyclic azadienes (1,2,4,5-tetrazines; 1,2,4-, 1,3,5-, and 1,2,3-triazines; 1,2-diazines; and 1,3,4-oxadiazoles), 1-aza-1,3-butadienes, α-pyrones, and cyclopropenone ketals. Their applications illustrate the power of the methodology, often provided concise and nonobvious total syntheses of the targeted natural products, typically were extended to the synthesis of analogues that contain deep-seated structural changes in more comprehensive studies to explore or optimize their biological properties, and highlight a wealth of opportunities not yet tapped.
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Affiliation(s)
- Jiajun Zhang
- Department of Chemistry and The Skaggs Institute for Chemical Biology , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Vyom Shukla
- Department of Chemistry and The Skaggs Institute for Chemical Biology , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Dale L Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States
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7
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Otrubova K, Chatterjee S, Ghimire S, Cravatt BF, Boger DL. N-Acyl pyrazoles: Effective and tunable inhibitors of serine hydrolases. Bioorg Med Chem 2019; 27:1693-1703. [PMID: 30879861 DOI: 10.1016/j.bmc.2019.03.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/08/2019] [Accepted: 03/08/2019] [Indexed: 11/24/2022]
Abstract
A series of N-acyl pyrazoles was examined as candidate serine hydrolase inhibitors in which the active site acylating reactivity and the leaving group ability of the pyrazole could be tuned not only through the nature of the acyl group (reactivity: amide > carbamate > urea), but also through pyrazole C4 substitution with electron-withdrawing or electron-donating substituents. Their impact on enzyme inhibitory activity displayed pronounced effects with the activity improving substantially as one alters both the nature of the reacting carbonyl group (urea > carbamate > amide) and the pyrazole C4 substituent (CN > H > Me). It was further demonstrated that the acyl chain of the N-acyl pyrazole ureas can be used to tailor the potency and selectivity of the inhibitor class to a targeted serine hydrolase. Thus, elaboration of the acyl chain of pyrazole-based ureas provided remarkably potent, irreversible inhibitors of fatty acid amide hydrolase (FAAH, apparent Ki = 100-200 pM), dual inhibitors of FAAH and monoacylglycerol hydrolase (MGLL), or selective inhibitors of MGLL (IC50 = 10-20 nM) while simultaneously minimizing off-target activity (e.g., ABHD6 and KIAA1363).
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Affiliation(s)
- Katerina Otrubova
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Shreyosree Chatterjee
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Srijana Ghimire
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Benjamin F Cravatt
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Dale L Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA.
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8
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Angelbello AJ, Chen JL, Childs-Disney JL, Zhang P, Wang ZF, Disney MD. Using Genome Sequence to Enable the Design of Medicines and Chemical Probes. Chem Rev 2018; 118:1599-1663. [PMID: 29322778 DOI: 10.1021/acs.chemrev.7b00504] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.
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Affiliation(s)
- Alicia J Angelbello
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jonathan L Chen
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jessica L Childs-Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Peiyuan Zhang
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Zi-Fu Wang
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Matthew D Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
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9
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Boger DL. The Difference a Single Atom Can Make: Synthesis and Design at the Chemistry-Biology Interface. J Org Chem 2017; 82:11961-11980. [PMID: 28945374 PMCID: PMC5712263 DOI: 10.1021/acs.joc.7b02088] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Indexed: 01/24/2023]
Abstract
A Perspective of work in our laboratory on the examination of biologically active compounds, especially natural products, is presented. In the context of individual programs and along with a summary of our work, selected cases are presented that illustrate the impact single atom changes can have on the biological properties of the compounds. The examples were chosen to highlight single heavy atom changes that improve activity, rather than those that involve informative alterations that reduce or abolish activity. The examples were also chosen to illustrate that the impact of such single-atom changes can originate from steric, electronic, conformational, or H-bonding effects, from changes in functional reactivity, from fundamental intermolecular interactions with a biological target, from introduction of a new or altered functionalization site, or from features as simple as improvements in stability or physical properties. Nearly all the examples highlighted represent not only unusual instances of productive deep-seated natural product modifications and were introduced through total synthesis but are also remarkable in that they are derived from only a single heavy atom change in the structure.
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Affiliation(s)
- Dale L. Boger
- Department of Chemistry and
The Skaggs Research Institute, The Scripps
Research Institute, 10550
North Torrey Pines Road, La Jolla, California 92037, United States
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10
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Abstract
(-)-Lomaiviticin A (4) is a complex C2-symmetric bacterial metabolite that contains two diazofluorene functional groups. The diazofluorene consists of naphthoquinone, cyclopentadiene, and diazo substituents fused through a σ- and π-bonding network. Additionally, (-)-lomaiviticin A (4) is a potent cytotoxin, with half-maximal inhibitory potency (IC50) values in the low nanomolar range against many cancer cell lines. Because of limitations in supply, its mechanism of action had remained a "black box" since its isolation in the early 2000s. In this Account, I describe how studies directed toward the total synthesis of (-)-lomaiviticin A (4) provided a platform to elucidate the emergent properties of this metabolite and thereby connect chemical reactivity with cellular phenotype. We first developed a convergent strategy to prepare the diazofluorene (9 + 10 → 13). We then adapted this chemistry to the synthesis of lomaiviticin aglycon (21/22) and the natural monomeric diazofluorene (-)-kinamycin F (3). The key step in the lomaiviticin aglycon (21/22) synthesis involved the stereoselective oxidative coupling of two monomeric diazofluorenes (2 × 18 → 20) to establish the cojoining carbon-carbon bond of the target. As the absolute stereochemistry of the aglycon and carbohydrate residues of (-)-lomaiviticin A (4) were unknown, we developed a semisynthetic route to the metabolite that proceeds in one step and 42% yield by diazo transfer to the more abundant isolate (-)-lomaiviticin C (6). This allowed us to complete the stereochemical assignment of (-)-lomaiviticin A (4) and provided a renewable source of material. Using this material, we established that the remarkable cytotoxic effects of (-)-lomaiviticin A (4) derive from the induction of highly toxic double-strand breaks (DSBs) in DNA. At the molecular level, 1,7-nucleophilic additions to each electrophilic diazofluorene trigger homolytic decomposition pathways that produce sp2 radicals at the carbon atoms of each diazo group. These radicals abstract hydrogen atoms from the deoxyribose of DNA, a process known to initiate strand cleavage. NMR spectroscopy and molecular mechanics simulations were used to elucidate the mode of DNA binding. These studies showed that both diazofluorenes of (-)-lomaiviticin A (4) penetrate into the duplex. This mode of non-covalent binding places each diazo carbon atom in close proximity to each DNA strand. Throughout these studies, isolates containing one diazofluorene, such as (-)-lomaiviticin C (6) and (-)-kinamycin C (2), were used as controls. Consistent with our mechanistic model, these compounds do not induce DSBs in DNA and are several orders of magnitude less potent. Reactivity studies suggest that (-)-lomaiviticin A (4) is more electrophilic than simple monomeric diazofluorenes. We attribute this to through-space delocalization of the developing negative charge in the transition state for 1,7-addition. Consistent with this mechanism of action, (-)-lomaiviticin A (4) displays selective low-picomolar potencies toward DNA DSB repair-deficient cell types. The emergent properties of (-)-lomaiviticin A (4) derive from the specific arrangement of diazo, naphthoquinone, cyclopentadiene, and ketone functional groups. These functional groups work together to yield, essentially, a masked vinyl radical that can be exposed under biological conditions. Furthermore, the rotational symmetry of the metabolite, deriving from dimerization, allows it to interact with the antiparallel symmetry of DNA and affect cleavage of the duplex.
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Affiliation(s)
- Seth B. Herzon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States. Department of Pharmacology, Yale School of Medicine, New Haven, Connecticut 06520, United States
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11
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Gillingham D, Geigle S, Anatole von Lilienfeld O. Properties and reactivity of nucleic acids relevant to epigenomics, transcriptomics, and therapeutics. Chem Soc Rev 2017; 45:2637-55. [PMID: 26992131 DOI: 10.1039/c5cs00271k] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Developments in epigenomics, toxicology, and therapeutic nucleic acids all rely on a precise understanding of nucleic acid properties and chemical reactivity. In this review we discuss the properties and chemical reactivity of each nucleobase and attempt to provide some general principles for nucleic acid targeting or engineering. For adenine-thymine and guanine-cytosine base pairs, we review recent quantum chemical estimates of their Watson-Crick interaction energy, π-π stacking energies, as well as the nuclear quantum effects on tautomerism. Reactions that target nucleobases have been crucial in the development of new sequencing technologies and we believe further developments in nucleic acid chemistry will be required to deconstruct the enormously complex transcriptome.
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Affiliation(s)
- Dennis Gillingham
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, Basel, CH-4056, Switzerland.
| | - Stefanie Geigle
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, Basel, CH-4056, Switzerland.
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12
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Jackson PJ, Rahman KM, Thurston DE. The use of molecular dynamics simulations to evaluate the DNA sequence-selectivity of G–A cross-linking PBD–duocarmycin dimers. Bioorg Med Chem Lett 2017; 27:102-108. [DOI: 10.1016/j.bmcl.2016.10.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 10/06/2016] [Accepted: 10/09/2016] [Indexed: 10/20/2022]
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13
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Chanda PB, Boyle KE, Brody DM, Shukla V, Boger DL. Synthesis and evaluation of duocarmycin SA analogs incorporating the methyl 1,2,8,8a-tetrahydrocyclopropa[c]imidazolo[4,5-e]indol-4-one-6-carboxylate (CImI) alkylation subunit. Bioorg Med Chem 2016; 24:4779-4786. [PMID: 27221071 DOI: 10.1016/j.bmc.2016.04.050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/18/2016] [Accepted: 04/23/2016] [Indexed: 10/21/2022]
Abstract
The design, synthesis, and evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]imidazolo[4,5-e]indol-4-one-6-carboxylate (CImI) derivatives are detailed representing analogs of duocarmycin SA and yatakemycin containing an imidazole replacement for the fused pyrrole found in the DNA alkylation subunit.
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Affiliation(s)
- Prem B Chanda
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Kristopher E Boyle
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Daniel M Brody
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Vyom Shukla
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Dale L Boger
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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14
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Structural basis for DNA cleavage by the potent antiproliferative agent (-)-lomaiviticin A. Proc Natl Acad Sci U S A 2016; 113:2851-6. [PMID: 26929332 DOI: 10.1073/pnas.1519846113] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
(-)-Lomaiviticin A (1) is a complex antiproliferative metabolite that inhibits the growth of many cultured cancer cell lines at low nanomolar-picomolar concentrations. (-)-Lomaiviticin A (1) possesses a C2-symmetric structure that contains two unusual diazotetrahydrobenzo[b]fluorene (diazofluorene) functional groups. Nucleophilic activation of each diazofluorene within 1 produces vinyl radical intermediates that affect hydrogen atom abstraction from DNA, leading to the formation of DNA double-strand breaks (DSBs). Certain DNA DSB repair-deficient cell lines are sensitized toward 1, and 1 is under evaluation in preclinical models of these tumor types. However, the mode of binding of 1 to DNA had not been determined. Here we elucidate the structure of a 1:1 complex between 1 and the duplex d(GCTATAGC)2 by NMR spectroscopy and computational modeling. Unexpectedly, we show that both diazofluorene residues of 1 penetrate the duplex. This binding disrupts base pairing leading to ejection of the central AT bases, while placing the proreactive centers of 1 in close proximity to each strand. DNA binding may also enhance the reactivity of 1 toward nucleophilic activation through steric compression and conformational restriction (an example of shape-dependent catalysis). This study provides a structural basis for the DNA cleavage activity of 1, will guide the design of synthetic DNA-activated DNA cleavage agents, and underscores the utility of natural products to reveal novel modes of small molecule-DNA association.
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Koch MF, Harteis S, Blank ID, Pestel G, Tietze LF, Ochsenfeld C, Schneider S, Sieber SA. Structural, Biochemical, and Computational Studies Reveal the Mechanism of Selective Aldehyde Dehydrogenase 1A1 Inhibition by Cytotoxic Duocarmycin Analogues. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201505749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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16
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Koch MF, Harteis S, Blank ID, Pestel G, Tietze LF, Ochsenfeld C, Schneider S, Sieber SA. Structural, Biochemical, and Computational Studies Reveal the Mechanism of Selective Aldehyde Dehydrogenase 1A1 Inhibition by Cytotoxic Duocarmycin Analogues. Angew Chem Int Ed Engl 2015; 54:13550-4. [DOI: 10.1002/anie.201505749] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/05/2015] [Indexed: 02/02/2023]
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17
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Uematsu M, Brody DM, Boger DL. A five-membered lactone prodrug of CBI-based analogs of the duocarmycins. Tetrahedron Lett 2015; 56:3101-3104. [PMID: 26069351 PMCID: PMC4459655 DOI: 10.1016/j.tetlet.2014.11.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The preparation, characterization and examination of the CBI-based 5-membered lactone 5 capable of serving as a prodrug or protein (antibody) conjugation reagent are disclosed along with its incorporation into the corresponding CC-1065 and duocarmycin analog 6, and the establishment of their properties.
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Affiliation(s)
- Mika Uematsu
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Daniel M. Brody
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Dale L. Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
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18
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Uematsu M, Boger DL. Asymmetric synthesis of a CBI-based cyclic N-acyl O-amino phenol duocarmycin prodrug. J Org Chem 2014; 79:9699-703. [PMID: 25247380 PMCID: PMC4201355 DOI: 10.1021/jo501839x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A short, asymmetric synthesis of a cyclic N-acyl O-amino phenol duocarmycin prodrug subject to reductive activation based on the simplified 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CBI) DNA alkylation subunit is described. A key element of the approach entailed treatment of iodo-epoxide 7, prepared by N-alkylation of 6 with (S)-glycidal 3-nosylate, with EtMgBr at room temperature to directly provide the optically pure alcohol 8 in 78% yield (99% ee) derived from an effective metal-halogen exchange and subsequent regioselective intramolecular 6-endo-tet cyclization. Following O-debenzylation, introduction of a protected N-methylhydroxamic acid, direct trannannular spirocyclization, and subsequent stereoelectronically controlled acid-catalyzed cleavage of the resulting cyclopropane (HCl), further improvements in a unique intramolecular cyclization with N-O bond formation originally introduced for formation of the reductively labile prodrug functionality are detailed.
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Affiliation(s)
- Mika Uematsu
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
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Shankar R, Radhika R, Thangamani D, Senthil Kumar L, Kolandaivel P. Theoretical studies on interaction of anticancer drugs (dacarbazine, procarbazine and triethylenemelamine) with normal (AT and GC) and mismatch (GG, CC, AA and TT) base pairs. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.913098] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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20
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Vielhauer GA, Swink M, Parelkar NK, Lajiness JP, Wolfe AL, Boger D. Evaluation of a reductively activated duocarmycin prodrug against murine and human solid cancers. Cancer Biol Ther 2014; 14:527-36. [PMID: 23760495 DOI: 10.4161/cbt.24348] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In treating cancer with clinically approved chemotherapies, the high systemic toxicity and lack of selectivity for malignant cells often result in an overall poor response rate. One pharmacological approach to improve patient response is to design targeted therapies that exploit the cancer milieu by reductively activating prodrugs, which results in the selective release of the free drug in the tumor tissue. Previously, we characterized prodrugs of seco-CBI-indole 2 (CBI-indole 2) designed to be activated in hypoxic tumor microenvironments, wherein the tumor maintains higher concentrations of "reducing" nucleophiles capable of preferentially releasing the free drug by nucleophilic attack on a weak N-O bond. Of these prodrugs, BocNHO-CBI-indole 2 (BocNHO) surpassed the efficacy of the free drug, CBI-indole 2, when examined in vivo in the murine L1210 leukemia model and demonstrated reduced toxicity suggesting a targeted or sustained release in vivo. Herein, we further examine the biological activity of the BocNHO prodrug in murine breast cancer, as well as human prostate and lung cancer cell lines, in vitro. Notably, BocNHO manifests potent antiproliferative and cytotoxic activity in all three tumor cell lines. However, in comparison to the activity observed in the murine cancer cell line, the human cancer cell lines were less sensitive, especially at early timepoints for cytotoxicity. Based on these findings, BocNHO was tested in a more clinically relevant orthotopic lung tumor model, revealing significant efficacy and reduced toxicity compared with the free drug. The data suggests that this pharmacological approach to designing targeted therapies is amenable to human solid tumors.
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Affiliation(s)
- George A Vielhauer
- Department of Urology, University of Kansas Medical Center, Kansas City, KS, USA.
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21
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Neo AG, López C, López A, Castedo L, Tojo G. Studies on the synthesis of a hindered analogue of the antitumour agent CC-1065. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.10.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Wolfe AL, Duncan KK, Lajiness JP, Zhu K, Duerfeldt AS, Boger DL. A fundamental relationship between hydrophobic properties and biological activity for the duocarmycin class of DNA-alkylating antitumor drugs: hydrophobic-binding-driven bonding. J Med Chem 2013; 56:6845-57. [PMID: 23944748 DOI: 10.1021/jm400665c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Two systematic series of increasingly hydrophilic derivatives of duocarmycin SA that feature the incorporation of ethylene glycol units (n = 1-5) into the methoxy substituents of the trimethoxyindole subunit are described. These derivatives exhibit progressively increasing water solubility along with progressive decreases in cell growth inhibitory activity and DNA alkylation efficiency with the incremental ethylene glycol unit incorporations. Linear relationships of cLogP with -log IC50 for cell growth inhibition and -log AE (AE = cell-free DNA alkylation efficiency) were observed, with the cLogP values spanning the productive range of 2.5-0.49 and the -log IC50 values spanning the range of 11.2-6.4, representing IC50 values that vary by a factor of 10(5) (0.008 to 370 nM). The results quantify the fundamental role played by the hydrophobic character of the compound in the expression of the biological activity of members in this class (driving the intrinsically reversible DNA alkylation reaction) and define the stunning magnitude of its effect.
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Affiliation(s)
- Amanda L Wolfe
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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23
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Wolfe AL, Duncan KK, Parelkar NK, Brown D, Vielhauer GA, Boger DL. Efficacious cyclic N-acyl O-amino phenol duocarmycin prodrugs. J Med Chem 2013; 56:4104-15. [PMID: 23627265 PMCID: PMC3687800 DOI: 10.1021/jm400413r] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Two novel cyclic N-acyl O-amino phenol prodrugs are reported as new members of a unique class of reductively cleaved prodrugs of the duocarmycin family of natural products. These prodrugs were explored with the expectation that they may be cleaved selectively within hypoxic tumor environments that have intrinsically higher concentrations of reducing nucleophiles and were designed to liberate the free drug without the release of an extraneous group. In vivo evaluation of the prodrug 6 showed that it exhibits extraordinary efficacy (T/C > 1500, L1210; 6/10 one year survivors), substantially exceeding that of the free drug, that its therapeutic window of activity is much larger, permitting a dosing ≥ 40-fold higher than the free drug, and yet that it displays a potency in vivo that approaches the free drug (within 3-fold). Clearly, the prodrug 6 benefits from either its controlled slow release of the free drug or its preferential intracellular reductive cleavage.
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Affiliation(s)
- Amanda L Wolfe
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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24
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25
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Deepa P, Kolandaivel P, Senthilkumar K. Structural properties and the effect of platinum drugs with DNA base pairs. Struct Chem 2012. [DOI: 10.1007/s11224-012-0087-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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26
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Wolfe AL, Duncan KK, Parelkar NK, Weir SJ, Vielhauer GA, Boger DL. A novel, unusually efficacious duocarmycin carbamate prodrug that releases no residual byproduct. J Med Chem 2012; 55:5878-86. [PMID: 22650244 PMCID: PMC3386426 DOI: 10.1021/jm300330b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A unique heterocyclic carbamate prodrug of seco-CBI-indole(2) that releases no residual byproduct is reported as a new member of a class of hydrolyzable prodrugs of the duocarmycin and CC-1065 family of natural products. The prodrug was designed to be activated by hydrolysis of a carbamate releasing the free drug without the cleavage release of a traceable extraneous group. Unlike prior carbamate prodrugs examined that are rapidly cleaved in vivo, the cyclic carbamate was found to be exceptionally stable to hydrolysis under both chemical and biological conditions providing a slow, sustained release of the exceptionally potent free drug. An in vivo evaluation of the prodrug found that its efficacy exceeded that of the parent drug, that its therapeutic window of efficacy versus toxicity is much larger than the parent drug, and that its slow free drug release permitted the safe and efficacious use of doses 150-fold higher than the parent compound.
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Affiliation(s)
- Amanda L. Wolfe
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Katharine K. Duncan
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Nikhil K. Parelkar
- University of Kansas Cancer Center, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | - Scott J. Weir
- University of Kansas Cancer Center, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | - George A. Vielhauer
- Department of Urology University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
- University of Kansas Cancer Center, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | - Dale L. Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
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27
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Theoretical investigation of interaction between psoralen and altretamine with stacked DNA base pairs. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2012. [DOI: 10.1016/j.msec.2011.11.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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28
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Thibodeaux CJ, Chang WC, Liu HW. Enzymatic chemistry of cyclopropane, epoxide, and aziridine biosynthesis. Chem Rev 2012; 112:1681-709. [PMID: 22017381 PMCID: PMC3288687 DOI: 10.1021/cr200073d] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Wei-chen Chang
- College of Pharmacy and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Hung-wen Liu
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- College of Pharmacy and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
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29
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Chen DYK, Pouwer RH, Richard JA. Recent advances in the total synthesis of cyclopropane-containing natural products. Chem Soc Rev 2012; 41:4631-42. [DOI: 10.1039/c2cs35067j] [Citation(s) in RCA: 403] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Deepa P, Kolandaivel P, Senthilkumar K. Hydrogen-bonding studies of amino acid side-chains with DNA base pairs. Mol Phys 2011. [DOI: 10.1080/00268976.2011.602649] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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31
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Otrubova K, Ezzili C, Boger DL. The discovery and development of inhibitors of fatty acid amide hydrolase (FAAH). Bioorg Med Chem Lett 2011; 21:4674-85. [PMID: 21764305 PMCID: PMC3146581 DOI: 10.1016/j.bmcl.2011.06.096] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2011] [Revised: 06/18/2011] [Accepted: 06/20/2011] [Indexed: 11/16/2022]
Abstract
A summary of the discovery and advancement of inhibitors of fatty acid amide hydrolase (FAAH) is presented.
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Affiliation(s)
- Katerina Otrubova
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey, Pines Road, La Jolla, CA 92037, USA
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32
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Lajiness JP, Boger DL. Asymmetric synthesis of 1,2,9,9a-tetrahydrocyclopropa[c]benzo[e]indol-4-one (CBI). J Org Chem 2011; 76:583-7. [PMID: 21192653 PMCID: PMC3079324 DOI: 10.1021/jo102136w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A short, asymmetric synthesis of the 1,2,9,9a-tetrahydrocyclopropa[c]benzo[e]indol-4-one (CBI) analogue of the CC-1065 and duocarmycin DNA alkylation subunits is described. Treatment of iodo-epoxide 5, prepared by late-stage alkylation of 4 with (S)-glycidal-3-nosylate, with EtMgBr at room temperature directly provides the optically pure alcohol 6 in 87% yield (99% ee) derived from selective metal-halogen exchange and subsequent regioselective intramolecular 6-endo-tet cyclization. The use of MeMgBr or i-PrMgBr also provides the product in high yields (82-87%), but requires larger amounts of the Grignard reagent to effect metal-halogen exchange and cyclization. Direct transannular spirocyclization of 7 following O-debenzylation of 6 provides N-Boc-CBI. This approach represents the most efficient (9-steps, 31% overall) and effective (99% ee) route to the optically pure CBI alkylation subunit yet described.
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Affiliation(s)
- James P. Lajiness
- Department of Chemistry and The Skaggs Institute for Chemical Biology,
The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla,
California 92037
| | - Dale L. Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology,
The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla,
California 92037
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33
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Lajiness JP, Robertson WM, Dunwiddie I, Broward MA, Vielhauer GA, Weir SJ, Boger DL. Design, synthesis, and evaluation of duocarmycin O-amino phenol prodrugs subject to tunable reductive activation. J Med Chem 2010; 53:7731-8. [PMID: 20942408 DOI: 10.1021/jm1010397] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of N-acyl O-amino derivatives of seco-CBI-indole(2) are reported and examined as prototypical members of a unique class of reductively activated (cleaved) prodrugs of the duocarmycin and CC-1065 family of antitumor agents. These prodrugs were designed to be potentially preferentially activated in hypoxic tumor environments which carry an intrinsically higher concentration of "reducing" nucleophiles (e.g., thiols) capable of activating such derivatives by nucleophilic cleavage of a weak N-O bond. A remarkable range of stabilities and a resulting direct correlation with in vitro/in vivo biological potencies was observed for these prodrugs, even enlisting subtle variations in the electronic and steric environment around the weak N-O bond. An in vivo evaluation of several of the prodrugs demonstrates that some approach the potency and exceed the efficacy of the free drug itself (CBI-indole(2)), suggesting the prodrugs may offer an additional advantage related to a controlled or targeted release.
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Affiliation(s)
- James P Lajiness
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Abstract
Bioactive natural products often possess uniquely functionalized structures with unusual modes of action; however, the natural product itself is not always the active species. We discuss molecules that draw on protecting group chemistry or else require activation to unmask reactive centers, illustrating that nature is not only a source of complex structures but also a guide for elegant chemical transformations which provides ingenious chemical solutions for drug delivery.
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Affiliation(s)
| | - Hendrik Luesch
- Department of Medicinal Chemistry, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610, USA
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35
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Lajiness JP, Boger DL. Synthesis and characterization of a cyclobutane duocarmycin derivative incorporating the 1,2,10,11-tetrahydro-9H-cyclobuta[c]benzo[e]indol-4-one (CbBI) alkylation subunit. J Am Chem Soc 2010; 132:13936-40. [PMID: 20839806 PMCID: PMC2952436 DOI: 10.1021/ja106986f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of 1,2,10,11-tetrahydro-9H-cyclobuta[c]benzo[e]indol-4-one (17, CbBI), which contains a deep-seated fundamental structural modification in the CC-1065 and duocarmycin alkylation subunit consisting of the incorporation of a ring-expanded fused cyclobutane (vs cyclopropane), its chemical and structural characterization, and its incorporation into a key analogue of the natural products are detailed. The approach to the preparation of CbBI was based on a precedented (Ar-3' and Ar-5') but previously unknown Ar-4' spirocyclization of a phenol onto a tethered alkyl halide to form the desired cyclobutane. The conditions required for the implementation of the Ar-4' spirocyclization indicate that the entropy of activation substantially impacts the rate of reaction relative to that for the much more facile Ar-3' spirocyclization, while the higher enthalpy of activation slows the reaction relative to an Ar-5' spirocyclization. The characterization of the CbBI-based agents revealed their exceptional stability and exquisite reaction regioselectivity, and a single-crystal X-ray structure analysis of N-Boc-CbBI (13) revealed their structural origins. The reaction regioselectivity may be attributed to the stereoelectronic alignment of the two available cyclobutane bonds with the cyclohexadienone π-system, which resides in the bond that extends to the less substituted cyclobutane carbon for 13. The remarkable stability of N-Boc-CbBI (which is stable even at pH 1) relative to N-Boc-CBI containing a cyclopropane (t(1/2) = 133 h at pH 3) may be attributed to a combination of the increased extent of vinylogous amide conjugation, the nonoptimal geometric alignment of the cyclobutane with the activating cyclohexadienone, and the intrinsic but modestly lower strain energy (1.8 kcal/mol) of a cyclobutane versus a cyclopropane.
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Affiliation(s)
- James P. Lajiness
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Dale L. Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
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36
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Robertson WM, Kastrinsky DB, Hwang I, Boger DL. Synthesis and evaluation of a series of C5'-substituted duocarmycin SA analogs. Bioorg Med Chem Lett 2010; 20:2722-5. [PMID: 20381346 PMCID: PMC2867475 DOI: 10.1016/j.bmcl.2010.03.078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Revised: 03/17/2010] [Accepted: 03/19/2010] [Indexed: 10/19/2022]
Abstract
The synthesis and evaluation of a key series of analogs of duocarmycin SA, bearing a single substituent at the C5' position of the DNA binding subunit, are described.
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Affiliation(s)
- William M. Robertson
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - David B. Kastrinsky
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Inkyu Hwang
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Dale L. Boger
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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37
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Synthesis and evaluation of duocarmycin SA analogs incorporating the methyl 1,2,8,8a-tetrahydrocyclopropa[c]oxazolo[2,3-e]indol-4-one-6-carboxylate (COI) alkylation subunit. Bioorg Med Chem Lett 2010; 20:1854-7. [PMID: 20171886 DOI: 10.1016/j.bmcl.2010.01.145] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 01/26/2010] [Accepted: 01/29/2010] [Indexed: 11/22/2022]
Abstract
The design, synthesis and evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]oxazolo[2,3-e]indol-4-one-6-carboxylate (COI) derivatives are detailed representing analogs of duocarmycin SA containing an oxazole replacement for the fused pyrrole found in the alkylation subunit.
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38
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Subramanian V, Williams RM, Boger DL, Luger K. Methods to characterize the effect of DNA-modifying compounds on nucleosomal DNA. Methods Mol Biol 2010; 613:173-192. [PMID: 19997884 DOI: 10.1007/978-1-60327-418-0_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Eukaryotic DNA forms a complex with an equal mass of proteins to form chromatin. To fully understand the action of DNA-reactive antitumor antibiotics in the cell, their effect must be studied in a chromatin context. In particular, it is of interest to investigate how the distortion of DNA, in the context of a nucleosome, affects the action of drugs with either monoalkylation or crosslinking activity, and how modified DNA is assembled into chromatin. Here, we present experimental approaches that allow one to compare the effect of such drugs on free DNA and nucleosomes. We find significant differences that likely arise from the different geometry of nucleosomal DNA compared to free DNA and also find that drug-mediated DNA crosslinking affects nucleosome assembly.
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Affiliation(s)
- Vidya Subramanian
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
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39
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Synthesis and evaluation of a thio analogue of duocarmycin SA. Bioorg Med Chem Lett 2009; 19:6962-5. [PMID: 19879753 DOI: 10.1016/j.bmcl.2009.10.063] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 10/10/2009] [Accepted: 10/13/2009] [Indexed: 11/21/2022]
Abstract
The design, synthesis, and preliminary evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]thieno[3,2-e]indol-4-one-6-carboxylate (CTI) derivatives are detailed representing a single atom change (N to S) embedded in the duocarmycin SA alkylation subunit.
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40
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MacMillan KS, Boger DL. Fundamental relationships between structure, reactivity, and biological activity for the duocarmycins and CC-1065. J Med Chem 2009; 52:5771-80. [PMID: 19639994 PMCID: PMC2755654 DOI: 10.1021/jm9006214] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Karen S MacMillan
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
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41
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Gauss CM, Hamasaki A, Parrish JP, Macmillan KS, Rayl TJ, Hwang I, Boger DL. Synthesis and Preliminary Evaluation of Duocarmycin Analogues Incorporating the 1,2,11,11a-Tetrahydrocyclopropa[c]naphtho[2,3-e]indol-4-one (CNI) and 1,2,11,11a-Tetrahydrocyclopropa[c]naphtho[1,2-e]indol-4-one (iso-CNI) Alkylation Subunits. Tetrahedron 2009; 65:6591-6599. [PMID: 20161204 DOI: 10.1016/j.tet.2009.02.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Efficient syntheses and a preliminary evaluation of 1,2,11,11a-tetrahydrocyclopropa[c]-naphtho[2,3-e]indole (CNI) and 1,2,11,11a-tetrahydrocyclopropa[c]naphtho[1,2-e]indole (iso-CNI), and their derivatives containing an anthracene and phenanthrene variant of the CC-1065 or duocarmycin alkylation subunit are detailed.
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Affiliation(s)
- Carla M Gauss
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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42
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MacMillan KS, Nguyen T, Nguyen T, Hwang I, Boger DL. Total synthesis and evaluation of iso-duocarmycin SA and iso-yatakemycin. J Am Chem Soc 2009; 131:1187-94. [PMID: 19154178 DOI: 10.1021/ja808108q] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The total synthesis and evaluation of iso-duocarmycin SA (5) and iso-yatakemycin (6), representing key analogues of the corresponding natural products incorporating an isomeric alkylation subunit, are detailed. This pyrrole isomer of the natural alkylation subunit displayed an enhanced reaction regioselectivity and a 2-fold diminished stability. Although still exceptionally potent, the iso-duocarmycin SA derivatives and natural product analogues exhibited a corresponding approximate 3-5-fold reduction in cytotoxic activity [L1210 IC(50) for (+)-iso-duocarmycin SA = 50 pM and for (+)-iso-yatakemycin = 15 pM] consistent with their placement on a parabolic relationship correlating activity with reactivity. The DNA alkylation selectivity of the resulting key natural product analogues was unaltered by the structure modification in spite of the minor-groove presentation of a potential H-bond donor. Additionally, a unique ortho-spirocyclization with such derivatives was explored via the preparation, characterization, and evaluation of 34 that is incapable of the more conventional para-spirocyclization. Although 34 proved sufficiently stable for isolation and characterization, it displayed little stability in protic solvents (t(1/2) = 0.19 h at pH 3, t(1/2) = 0.20 h at pH 7), a pH-independent (H(+) independent) solvolysis rate profile at pH 3/4-7, and a much reduced cytotoxic potency, but a DNA alkylation selectivity and efficiency comparable to those of duocarmycin SA and iso-duocarmycin SA. The implications of these observations on the source of the DNA alkylation selectivity and catalysis for this class of natural products are discussed.
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Affiliation(s)
- Karen S MacMillan
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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43
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Al-Said NH, Shawakfeh KQ, Hammad BA. A facile rearrangement of pyrroloindoline derivative to pyrroloquinoline: A new analogues of duocarmycins. J Heterocycl Chem 2008. [DOI: 10.1002/jhet.5570450513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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44
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Interactions of anticancer drugs with usual and mismatch base pairs — Density functional theory studies. Biophys Chem 2008; 136:50-8. [DOI: 10.1016/j.bpc.2008.04.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 04/22/2008] [Accepted: 04/22/2008] [Indexed: 01/18/2023]
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45
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Di Micco S, Boger DL, Riccio R, Bifulco G. Structural Features of the (+)-Yatakemycin/d(GACTAATTGAC)-(GTCAATTAGTC) Complex – Quantum Mechanical Calculation of NMR Parameters as a Tool for the Characterization of Ligand/DNA Interactions. European J Org Chem 2008. [DOI: 10.1002/ejoc.200701212] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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46
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Jin W, Trzupek JD, Rayl TJ, Broward MA, Vielhauer GA, Weir SJ, Hwang I, Boger DL. A unique class of duocarmycin and CC-1065 analogues subject to reductive activation. J Am Chem Soc 2007; 129:15391-7. [PMID: 18020335 PMCID: PMC2519901 DOI: 10.1021/ja075398e] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
N-Acyl O-amino phenol derivatives of CBI-TMI and CBI-indole2 are reported as prototypical members of a new class of reductively activated prodrugs of the duocarmycin and CC-1065 class of antitumor agents. The expectation being that hypoxic tumor environments, with their higher reducing capacity, carry an intrinsic higher concentration of "reducing" nucleophiles (e.g., thiols) capable of activating such derivatives (tunable N-O bond cleavage) and increasing their sensitivity to the prodrug treatment. Preliminary studies indicate the prodrugs effectively release the free drug in functional cellular assays for cytotoxic activity approaching or matching the activity of the free drug, yet remain essentially stable and unreactive to in vitro DNA alkylation conditions (<0.1-0.01% free drug release) and pH 7.0 phosphate buffer, and exhibit a robust half-life in human plasma (t1/2 = 3 h). Characterization of a representative O-(acylamino) prodrug in vivo indicates that they approach the potency and exceed the efficacy of the free drug itself (CBI-indole2), indicating that not only is the free drug effectively released from the inactive prodrug but also that they offer additional advantages related to a controlled or targeted release in vivo.
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Affiliation(s)
- Wei Jin
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, E-mail:
| | - John D. Trzupek
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, E-mail:
| | - Thomas J. Rayl
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, E-mail:
| | - Melinda A. Broward
- Office of Therapeutics, Discovery and Development, University of Kansas Cancer Center, 3901 Rainbow Blvd., Kansas City, Kansas 66160
| | - George A. Vielhauer
- Office of Therapeutics, Discovery and Development, University of Kansas Cancer Center, 3901 Rainbow Blvd., Kansas City, Kansas 66160
| | - Scott J. Weir
- Office of Therapeutics, Discovery and Development, University of Kansas Cancer Center, 3901 Rainbow Blvd., Kansas City, Kansas 66160
| | - Inkyu Hwang
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, E-mail:
| | - Dale L. Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, E-mail:
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47
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Tichenor MS, Boger DL. Yatakemycin: total synthesis, DNA alkylation, and biological properties. Nat Prod Rep 2007; 25:220-6. [PMID: 18389136 DOI: 10.1039/b705665f] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
DNA-binding small molecules are an important source of anticancer therapeutics that display a diverse array of mechanisms of action. Synthetic studies on the new DNA-alkylating natural product yatakemycin, detailed in this Highlight, have served to reassign its structure, assign the absolute stereochemistry, and provide access to yatakemycin and a series of structural analogues for biological evaluation. Studies on the DNA alkylation properties of (+)-and ent-(-)-yatakemycin and related analogues have demonstrated the enhanced DNA alkylation properties of this class of agents and provided insight into their interaction with DNA.
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Affiliation(s)
- Mark S Tichenor
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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48
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Tichenor MS, MacMillan KS, Stover JS, Wolkenberg SE, Pavani MG, Zanella L, Zaid AN, Spalluto G, Rayl TJ, Hwang I, Baraldi PG, Boger DL. Rational design, synthesis, and evaluation of key analogues of CC-1065 and the duocarmycins. J Am Chem Soc 2007; 129:14092-9. [PMID: 17948994 DOI: 10.1021/ja073989z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The design, synthesis, and evaluation of a predictably more potent analogue of CC-1065 entailing the substitution replacement of a single skeleton atom in the alkylation subunit are disclosed and were conducted on the basis of design principles that emerged from a fundamental parabolic relationship between chemical reactivity and cytotoxic potency. Consistent with projections, the 7-methyl-1,2,8,8a-tetrahydrocyclopropa[c]thieno[3,2-e]indol-4-one (MeCTI) alkylation subunit and its isomer 6-methyl-1,2,8,8a-tetrahydrocyclopropa[c]thieno[2,3-e]indol-4-one (iso-MeCTI) were found to be 5-6 times more stable than the MeCPI alkylation subunit found in CC-1065 and slightly more stable than even the DSA alkylation subunit found in duocarmycin SA, placing it at the point of optimally balanced stability and reactivity for this class of antitumor agents. Their incorporation into the key analogues of the natural products provided derivatives that surpassed the potency of MeCPI derivatives (3-10-fold), matching or slightly exceeding the potency of the corresponding DSA derivatives, consistent with projections made on the basis of the parabolic relationship. Notable of these, MeCTI-TMI proved to be as potent as or slightly more potent than the natural product duocarmycin SA (DSA-TMI, IC50 = 5 vs 8 pM), and MeCTI-PDE2 proved to be 3-fold more potent than the natural product CC-1065 (MeCPI-PDE2, IC50 = 7 vs 20 pM). Both exhibited efficiencies of DNA alkylation that correlate with this enhanced potency without impacting the intrinsic selectivity characteristic of this class of antitumor agents.
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Affiliation(s)
- Mark S Tichenor
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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49
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Tichenor MS, MacMillan KS, Trzupek JD, Rayl TJ, Hwang I, Boger DL. Systematic exploration of the structural features of yatakemycin impacting DNA alkylation and biological activity. J Am Chem Soc 2007; 129:10858-69. [PMID: 17691783 PMCID: PMC2519902 DOI: 10.1021/ja072777z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A systematic examination of the impact of the yatakemycin left and right subunits and their substituents is detailed along with a study of its unique three subunit arrangement (sandwiched vs extended and reversed analogues). The examination of the ca. 50 analogues prepared illustrate that within the yatakemycin three subunit structure, the subunit substituents are relatively unimportant and that it is the unique sandwiched arrangement that substantially increases the rate and optimizes the efficiency of its DNA alkylation reaction. This potentiates the cytotoxic activity of yatakemycin and its analogues overcoming limitations typically observed with more traditional compounds in the series (CC-1065, duocarmycins). Moreover, a study of the placement of the alkylation subunit within the three subunit arrangement (sandwiched vs extended and reversed analogues) indicates that it not only has a profound impact on the rate and efficiency of DNA alkylation but also controls and establishes the DNA alkylation selectivity as well, where both enantiomers of such sandwiched agents alkylate the same adenine sites exhibiting the same DNA alkylation selectivity independent of their absolute configuration.
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50
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Tichenor MS, Trzupek JD, Kastrinsky DB, Shiga F, Hwang I, Boger DL. Asymmetric total synthesis of (+)- and ent-(-)-yatakemycin and duocarmycin SA: evaluation of yatakemycin key partial structures and its unnatural enantiomer. J Am Chem Soc 2006; 128:15683-96. [PMID: 17147378 PMCID: PMC2515590 DOI: 10.1021/ja064228j] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Complementary to studies that provided the first yatakemycin total synthesis resulting in its structure revision and absolute stereochemistry assignment, a second-generation asymmetric total synthesis is disclosed herein. Since the individual yatakemycin subunits are identical to those of duocarmycin SA (alkylation subunit) or CC-1065 (central and right-hand subunits), the studies also provide an improvement in our earlier total synthesis of CC-1065 and, as detailed herein, have been extended to an asymmetric total synthesis of (+)-duocarmycin SA. Further extensions of the studies provided key yatakemycin partial structures and analogues for comparative assessments. This included the definition of the DNA selectivity (adenine central to a five-base-pair AT sequence, e.g., 5'-AAAAA), efficiency, relative rate, and reversibility of ent-(-)-yatakemycin and its comparison with the natural enantiomer (identical selectivity and efficiency), structural characterization of the adenine N3 adduct confirming the nature of the DNA reaction, and comparisons of the cytotoxic activity of the natural product (L1210, IC50 = 5 pM) with those of its unnatural enantiomer (IC50 = 5 pM) and a series of key partial structures including those that probe the role of the C-terminus thiomethyl ester. The only distinguishing features between the enantiomers is that ent-(-)-yatakemycin alkylates DNA at a slower rate (krel = 0.13) and is reversible, whereas (+)-yatakemycin is not. Nonetheless, even ent-(-)-yatakemycin alkylates DNA at a faster rate and with a greater thermodynamic stability than (+)-duocarmycin SA, illustrating the unique characteristics of such "sandwiched" agents.
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Affiliation(s)
- Mark S. Tichenor
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - John D. Trzupek
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - David B. Kastrinsky
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Futoshi Shiga
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Inkyu Hwang
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Dale L. Boger
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
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