Co-reporter:Meredith A. Saunders;Khaled A. Shaaban;Yinan Zhang;Xiachang Wang;Tuan Tran;Jianjun Zhang;Sherif I. Elshahawi;Gregory C. Copley;Larissa V. Ponomareva;Madan K. Kharel;Andrew J. Morris;Jon S. Thorson;James C. Hower;Manjula Sunkara;Mark A. Prendergast;Matthew S. Tremblay
Journal of Natural Products January 27, 2017 Volume 80(Issue 1) pp:2-11
Publication Date(Web):December 28, 2016
DOI:10.1021/acs.jnatprod.6b00948
The isolation and structure elucidation of six new bacterial metabolites [spoxazomicin D (2), oxachelins B and C (4, 5), and carboxamides 6–8] and 11 previously reported bacterial metabolites (1, 3, 9–12a, and 14–18) from Streptomyces sp. RM-14-6 is reported. Structures were elucidated on the basis of comprehensive 1D and 2D NMR and mass spectrometry data analysis, along with direct comparison to synthetic standards for 2, 11, and 12a,b. Complete 2D NMR assignments for the known metabolites lenoremycin (9) and lenoremycin sodium salt (10) were also provided for the first time. Comparative analysis also provided the basis for structural revision of several previously reported putative aziridine-containing compounds [exemplified by madurastatins A1, B1, C1 (also known as MBJ-0034), and MBJ-0035] as phenol-dihydrooxazoles. Bioactivity analysis [including antibacterial, antifungal, cancer cell line cytotoxicity, unfolded protein response (UPR) modulation, and EtOH damage neuroprotection] revealed 2 and 5 as potent neuroprotectives and lenoremycin (9) and its sodium salt (10) as potent UPR modulators, highlighting new functions for phenol-oxazolines/salicylates and polyether pharmacophores.
Co-reporter:Jianjun Zhang, Ryan R. Hughes, Meredith A. Saunders, Sherif I. Elshahawi, Larissa V. Ponomareva, Yinan Zhang, Sydney R. Winchester, Samantha A. Scott, Manjula Sunkara, Andrew J. Morris, Mark A. Prendergast, Khaled A. Shaaban, and Jon S. Thorson
Journal of Natural Products 2017 Volume 80(Issue 1) pp:
Publication Date(Web):December 28, 2016
DOI:10.1021/acs.jnatprod.6b00949
The assessment of glycosyl-scanning to expand the molecular and functional diversity of metabolites from the underground coal mine fire-associated Streptomyces sp. RM-14-6 is reported. Using the engineered glycosyltransferase OleD Loki and a 2-chloro-4-nitrophenylglycoside-based screen, six metabolites were identified as substrates of OleD Loki, from which 12 corresponding metabolite glycosides were produced and characterized. This study highlights the first application of the 2-chloro-4-nitrophenylglycoside-based screen toward an unbiased set of unique microbial natural products and the first reported application of the 2-chloro-4-nitrophenylglycoside-based transglycosylation reaction for the corresponding preparative synthesis of target glycosides. Bioactivity analysis (including antibacterial, antifungal, anticancer, and EtOH damage neuroprotection assays) revealed glycosylation to attenuate the neuroprotective potency of 4, while glycosylation of the structurally related inactive spoxazomicin C (3) remarkably invoked neuroprotective activity.
Co-reporter:Tyler D. Huber, Fengbin Wang, Shanteri Singh, Brooke R. Johnson, Jianjun Zhang, Manjula Sunkara, Steven G. Van Lanen, Andrew J. Morris, George N. Phillips Jr., and Jon S. Thorson
ACS Chemical Biology 2016 Volume 11(Issue 9) pp:2484
Publication Date(Web):June 28, 2016
DOI:10.1021/acschembio.6b00348
S-adenosyl-l-methionine (AdoMet) is an essential enzyme cosubstrate in fundamental biology with an expanding range of biocatalytic and therapeutic applications. We report the design, synthesis, and evaluation of stable, functional AdoMet isosteres that are resistant to the primary contributors to AdoMet degradation (depurination, intramolecular cyclization, and sulfonium epimerization). Corresponding biochemical and structural studies demonstrate the AdoMet surrogates to serve as competent enzyme cosubstrates and to bind a prototypical class I model methyltransferase (DnrK) in a manner nearly identical to AdoMet. Given this conservation in function and molecular recognition, the isosteres presented are anticipated to serve as useful surrogates in other AdoMet-dependent processes and may also be resistant to, and/or potentially even inhibit, other therapeutically relevant AdoMet-dependent metabolic transformations (such as the validated drug target AdoMet decarboxylase). This work also highlights the ability of the prototypical class I model methyltransferase DnrK to accept non-native surrogate acceptors as an enabling feature of a new high-throughput methyltransferase assay.
Co-reporter:Sherif I. Elshahawi, Khaled A. Shaaban, Madan K. Kharel and Jon S. Thorson
Chemical Society Reviews 2015 vol. 44(Issue 21) pp:7591-7697
Publication Date(Web):04 Mar 2015
DOI:10.1039/C4CS00426D
A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.
Co-reporter:Xiachang Wang, Anna R. Reynolds, Sherif I. Elshahawi, Khaled A. Shaaban, Larissa V. Ponomareva, Meredith A. Saunders, Ibrahim S. Elgumati, Yinan Zhang, Gregory C. Copley, James C. Hower, Manjula Sunkara, Andrew J. Morris, Madan K. Kharel, Steven G. Van Lanen, Mark A. Prendergast, and Jon S. Thorson
Organic Letters 2015 Volume 17(Issue 11) pp:2796-2799
Publication Date(Web):May 11, 2015
DOI:10.1021/acs.orglett.5b01203
Terfestatins B (1) and C (2), new p-terphenyls bearing a novel unsaturated hexuronic acid (4-deoxy-α-l-threo-hex-4-enopyranuronate), a unique β-d-glycosyl ester of 5-isoprenylindole-3-carboxylate (3) and the same rare sugar, and two new hygromycin precursors, were characterized as metabolites of the coal mine fire isolate Streptomyces sp. RM-5–8. EtOH damage neuroprotection assays using rat hippocampal-derived primary cell cultures with 1, 2, 3 and echoside B (a terfestatin C-3′-β-d-glucuronide from Streptomyces sp. RM-5–8) revealed 1 as potently neuroprotective, highlighting a new potential application of the terfestatin scaffold.
Co-reporter:Fengbin Wang, Shanteri Singh, Weijun Xu, Kate E. Helmich, Mitchell D. Miller, Hongnan Cao, Craig A. Bingman, Jon S. Thorson, and George N. Phillips Jr.
ACS Chemical Biology 2015 Volume 10(Issue 9) pp:2048
Publication Date(Web):May 29, 2015
DOI:10.1021/acschembio.5b00244
Sugar aminotransferases (SATs) are an important class of tailoring enzymes that catalyze the 5′-pyridoxal phosphate (PLP)-dependent stereo- and regiospecific installation of an amino group from an amino acid donor (typically l-Glu or l-Gln) to a corresponding ketosugar nucleotide acceptor. Herein we report the strategic structural study of two homologous C4 SATs (Micromonospora echinospora CalS13 and Escherichia coli WecE) that utilize identical substrates but differ in their stereochemistry of aminotransfer. This study reveals for the first time a new mode of SAT sugar nucleotide binding and, in conjunction with previously reported SAT structural studies, provides the basis from which to propose a universal model for SAT stereo- and regiochemical control of amine installation. Specifically, the universal model put forth highlights catalytic divergence to derive solely from distinctions within nucleotide sugar orientation upon binding within a relatively fixed SAT active site where the available ligand bound structures of the three out of four representative C3 and C4 SAT examples provide a basis for the overall model. Importantly, this study presents a new predictive model to support SAT functional annotation, biochemical study and rational engineering.
Co-reporter:Khaled A. Shaaban; Sherif I. Elshahawi; Xiachang Wang; Jamie Horn; Madan K. Kharel; Markos Leggas;Jon S. Thorson
Journal of Natural Products 2015 Volume 78(Issue 7) pp:1723-1729
Publication Date(Web):June 19, 2015
DOI:10.1021/acs.jnatprod.5b00429
Actinomadura melliaura ATCC 39691, a strain isolated from a soil sample collected in Bristol Cove, California, is a known producer of the disaccharide-substituted AT2433 indolocarbazoles (6–9). Reinvestigation of this strain using new media conditions led to >40-fold improvement in the production of previously reported AT2433 metabolites and the isolation and structure elucidation of the four new analogues, AT2433-A3, A4, A5, and B3 (1–4). The availability of this broader set of compounds enabled a subsequent small antibacterial/fungal/cancer SAR study that revealed disaccharyl substitution, N-6 methylation, and C-11 chlorination as key modulators of bioactivity. The slightly improved anticancer potency of the newly reported N-6-desmethyl 1 (compared to 6) contrasts extensive SAR of monoglycosylated rebeccamycin-type topoisomerase I inhibitors where N-6 alkylation has contributed to improved potency and ADME. Complete 2D NMR assignments for the known metabolite BMY-41219 (5) and 13C NMR spectroscopic data for the known analogue AT2433-B1 (7) are also provided for the first time.
Co-reporter:Jianjun Zhang, Larissa V. Ponomareva, Nitin S. Nandurkar, Yaxia Yuan, Lei Fang, Chang-Guo Zhan, and Jon S. Thorson
ACS Medicinal Chemistry Letters 2015 Volume 6(Issue 10) pp:1053
Publication Date(Web):August 12, 2015
DOI:10.1021/acsmedchemlett.5b00120
The synthesis of a set of digitoxigenin neogluco/xylosides and corresponding study of their anticancer SAR revealed sugar amine regiochemistry has a dramatic effect upon activity. Specifically, this study noted sugar 3-amino followed by 4-amino-substitution to be most advantageous where the solvent accessibility of the appended amine within neoglycoside-Na+,K+-ATPase docked models correlated with increased anticancer potency. This study presents a preliminary model for potential further warhead optimization in the context of antibody-directed steroidal glycosides and extends the demonstrated compatibility of aminosugars in the context of neoglycosylation.Keywords: digitoxigenin; neoglycosylation; Regiochemistry; sugar
Co-reporter:Dr. Yinan Zhang;Dr. Qing Ye;Dr. Xiachang Wang; Qing-Bai She; Jon S. Thorson
Angewandte Chemie 2015 Volume 127( Issue 38) pp:11371-11374
Publication Date(Web):
DOI:10.1002/ange.201505022
Abstract
The first enantioselective total synthesis of griseusin A, griseusin C, 4′-deacetyl-griseusin A, and two non-native counterparts in 11–14 steps is reported. This strategy highlights a key hydroxy-directed CH olefination of 1-methylene isochroman with an α,β-unsaturated ketone followed by subsequent stereoselective epoxidation and regioselective cyclization to afford the signature tetrahydro-spiropyran ring. Colorectal cancer cell cytotoxicities of the final products highlight the impact of the griseusin tetrahydro-spiropyran ring on bioactivity. As the first divergent enantioselective synthesis, the strategy put forth sets the stage for further griseusin mechanism-of-action and SAR studies.
Co-reporter:Dr. Yinan Zhang;Dr. Qing Ye;Dr. Xiachang Wang; Qing-Bai She; Jon S. Thorson
Angewandte Chemie International Edition 2015 Volume 54( Issue 38) pp:11219-11222
Publication Date(Web):
DOI:10.1002/anie.201505022
Abstract
The first enantioselective total synthesis of griseusin A, griseusin C, 4′-deacetyl-griseusin A, and two non-native counterparts in 11–14 steps is reported. This strategy highlights a key hydroxy-directed CH olefination of 1-methylene isochroman with an α,β-unsaturated ketone followed by subsequent stereoselective epoxidation and regioselective cyclization to afford the signature tetrahydro-spiropyran ring. Colorectal cancer cell cytotoxicities of the final products highlight the impact of the griseusin tetrahydro-spiropyran ring on bioactivity. As the first divergent enantioselective synthesis, the strategy put forth sets the stage for further griseusin mechanism-of-action and SAR studies.
Co-reporter:Dr. Pauline Peltier-Pain;Dr. Shanteri Singh; Jon S. Thorson
ChemBioChem 2015 Volume 16( Issue 15) pp:2141-2146
Publication Date(Web):
DOI:10.1002/cbic.201500365
Abstract
The characterization of TDP-α-d-glucose dehydrogenase (AtmS8), TDP-α-d-glucuronic acid decarboxylase (AtmS9), and TDP-4-keto-α-d-xylose 2,3-dehydratase (AtmS14), involved in Actinomadura melliaura AT2433 aminodideoxypentose biosynthesis, is reported. This study provides the first biochemical evidence that both deoxypentose and deoxyhexose biosynthetic pathways share common strategies for sugar 2,3-dehydration/reduction and implicates the sugar nucleotide base specificity of AtmS14 as a potential mechanism for sugar nucleotide commitment to secondary metabolism. In addition, a re-evaluation of the AtmS9 homologue involved in calicheamicin aminodeoxypentose biosynthesis (CalS9) reveals that CalS9 catalyzes UDP-4-keto-α-d-xylose as the predominant product, rather than UDP-α-d-xylose as previously reported. Cumulatively, this work provides additional fundamental insights regarding the biosynthesis of novel pentoses attached to complex bacterial secondary metabolites.
Co-reporter:Xiachang Wang, Sherif I. Elshahawi, Khaled A. Shaaban, Lei Fang, Larissa V. Ponomareva, Yinan Zhang, Gregory C. Copley, James C. Hower, Chang-Guo Zhan, Madan K. Kharel, and Jon S. Thorson
Organic Letters 2014 Volume 16(Issue 2) pp:456-459
Publication Date(Web):December 16, 2013
DOI:10.1021/ol4033418
The isolation and structural elucidation of a new tetracyclic polyketide (ruthmycin) from Streptomyces sp. RM-4-15, a bacteria isolated near thermal vents from the Ruth Mullins underground coal mine fire in eastern Kentucky, is reported. In comparison to the well-established frenolicin core scaffold, ruthmycin possesses an unprecedented signature C3 bridge and a corresponding fused six member ring. Preliminary in vitro antibacterial, anticancer, and antifungal assays revealed ruthmycin to display moderate antifungal activity.
Co-reporter:Shanteri Singh, Pauline Peltier-Pain, Marco Tonelli, and Jon S. Thorson
Organic Letters 2014 Volume 16(Issue 12) pp:3220-3223
Publication Date(Web):June 9, 2014
DOI:10.1021/ol501241a
A simple method for the study of sugar-nucleotide-dependent multienzyme cascades is highlighted where the use of selectively 13C-labeled sugar nucleotides and inverse 13C detection NMR offers fast, direct detection and quantification of reactants and products and circumvents the need for chromatographic separation. The utility of the method has been demonstrated by characterizing four previously uncharacterized sugar nucleotide biosynthetic enzymes involved in calicheamicin biosynthesis.
Co-reporter:Nitin S. Nandurkar ; Jianjun Zhang ; Qing Ye ; Larissa V. Ponomareva ; Qing-Bai She ;Jon S. Thorson
Journal of Medicinal Chemistry 2014 Volume 57(Issue 17) pp:7478-7484
Publication Date(Web):August 14, 2014
DOI:10.1021/jm500870u
A facile route to perillyl alcohol (POH) differential glycosylation and the corresponding synthesis of a set of 34 POH glycosides is reported. Subsequent in vitro studies revealed a sugar dependent antiproliferative activity and the inhibition of S6 ribosomal protein phosphorylation as a putative mechanism of representative POH glycosides. The most active glycoside from this cumulative study (4′-azido-d-glucoside, PG9) represents one of the most cytotoxic POH analogues reported to date.
Co-reporter:Sherif I. Elshahawi, Theresa A. Ramelot, Jayaraman Seetharaman, Jing Chen, Shanteri Singh, Yunhuang Yang, Kari Pederson, Madan K. Kharel, Rong Xiao, Scott Lew, Ragothaman M. Yennamalli, Mitchell D. Miller, Fengbin Wang, Liang Tong, Gaetano T. Montelione, Michael A. Kennedy, Craig A. Bingman, Haining Zhu, George N. Phillips Jr., and Jon S. Thorson
ACS Chemical Biology 2014 Volume 9(Issue 10) pp:2347
Publication Date(Web):July 31, 2014
DOI:10.1021/cb500327m
Calicheamicin γ1I (1) is an enediyne antitumor compound produced by Micromonospora echinospora spp. calichensis, and its biosynthetic gene cluster has been previously reported. Despite extensive analysis and biochemical study, several genes in the biosynthetic gene cluster of 1 remain functionally unassigned. Using a structural genomics approach and biochemical characterization, two proteins encoded by genes from the 1 biosynthetic gene cluster assigned as “unknowns”, CalU16 and CalU19, were characterized. Structure analysis revealed that they possess the STeroidogenic Acute Regulatory protein related lipid Transfer (START) domain known mainly to bind and transport lipids and previously identified as the structural signature of the enediyne self-resistance protein CalC. Subsequent study revealed calU16 and calU19 to confer resistance to 1, and reminiscent of the prototype CalC, both CalU16 and CalU19 were cleaved by 1 in vitro. Through site-directed mutagenesis and mass spectrometry, we identified the site of cleavage in each protein and characterized their function in conferring resistance against 1. This report emphasizes the importance of structural genomics as a powerful tool for the functional annotation of unknown proteins.
Co-reporter:Randal D. Goff and Jon. S. Thorson
MedChemComm 2014 vol. 5(Issue 8) pp:1036-1047
Publication Date(Web):23 Apr 2014
DOI:10.1039/C4MD00117F
This review focuses upon the development, scope, and utility of the highly versatile chemoselective alkoxyamine-based ‘neoglycosylation’ reaction first described by Peri and Dumy. The fundamentals of neoglycosylation and the subsequent development of a ‘neoglycorandomization’ platform to afford differentially-glycosylated libraries of plant-based natural products, microbial-based natural products, and small molecule-based drugs for drug discovery applications are discussed.
Co-reporter:Xiachang Wang, Khaled A Shaaban, Sherif I Elshahawi, Larissa V Ponomareva, Manjula Sunkara, Gregory C Copley, James C Hower, Andrew J Morris, Madan K Kharel and Jon S Thorson
The Journal of Antibiotics 2014 67(8) pp:571-575
Publication Date(Web):April 9, 2014
DOI:10.1038/ja.2014.37
Two new cyclopeptides, mullinamides A [cyclo-(-L-Gly-L-Glu-L-Val-L-Ile-L-Pro-)] and B [cyclo-(-L-Glu-L-Met-L-Pro-)] were isolated from the crude extract of terrestrial Streptomyces sp. RM-27-46 along with the three known cyclopeptides surugamide A [cyclo-(-L-Ile-D-Ile-L-Lys-L-Ile-D-Phe-D-Leu-L-Ile-D-Ala-)], cyclo-(-L-Pro-L-Phe-) and cyclo-(-L-Pro-L-Leu-). The structures of the new compounds were elucidated by the cumulative analyses of NMR spectroscopy and HRMS. Although mullinamides A and B displayed no appreciable antimicrobial/fungal activity or cytotoxicity, this study highlights the first reported antibacterial activity of surugamide A.
Co-reporter:Zhiqiang Chen, Jianjun Zhang, Shanteri Singh, Pauline Peltier-Pain, Jon S. Thorson, and Bruce J. Hinds
ACS Nano 2014 Volume 8(Issue 8) pp:8104
Publication Date(Web):July 15, 2014
DOI:10.1021/nn502181k
A nanoporous membrane system with directed flow carrying reagents to sequentially attached enzymes to mimic nature’s enzyme complex system was demonstrated. Genetically modified glycosylation enzyme, OleD Loki variant, was immobilized onto nanometer-scale electrodes at the pore entrances/exits of anodic aluminum oxide membranes through His6-tag affinity binding. The enzyme activity was assessed in two reactions—a one-step “reverse” sugar nucleotide formation reaction (UDP-Glc) and a two-step sequential sugar nucleotide formation and sugar nucleotide-based glycosylation reaction. For the one-step reaction, enzyme specific activity of 6–20 min–1 on membrane supports was seen to be comparable to solution enzyme specific activity of 10 min–1. UDP-Glc production efficiencies as high as 98% were observed at a flow rate of 0.5 mL/min, at which the substrate residence time over the electrode length down pore entrances was matched to the enzyme activity rate. This flow geometry also prevented an unwanted secondary product hydrolysis reaction, as observed in the test homogeneous solution. Enzyme utilization increased by a factor of 280 compared to test homogeneous conditions due to the continuous flow of fresh substrate over the enzyme. To mimic enzyme complex systems, a two-step sequential reaction using OleD Loki enzyme was performed at membrane pore entrances then exits. After UDP-Glc formation at the entrance electrode, aglycon 4-methylumbelliferone was supplied at the exit face of the reactor, affording overall 80% glycosylation efficiency. The membrane platform showed the ability to be regenerated with purified enzyme as well as directly from expression crude, thus demonstrating a single-step immobilization and purification process.Keywords: biomimetic enzyme immobilization; enzyme purification; glycosylation; glycosyltransferase; membrane−electrode; sequential reactions
Co-reporter:Dr. Jianjun Zhang; Shanteri Singh;Ryan R. Hughes;Dr. Maoquan Zhou;Manjula Sunkara; Andrew J. Morris; Jon S. Thorson
ChemBioChem 2014 Volume 15( Issue 5) pp:647-651
Publication Date(Web):
DOI:10.1002/cbic.201300779
Abstract
A set of 2-chloro-4-nitrophenyl glucosamino-/xylosaminosides were synthesized and assessed as potential substrates in the context of glycosyltransferase-catalyzed formation of the corresponding UDP/TDP-α-D-glucosamino-/xylosaminosugars and in single-vessel model transglycosylation reactions. This study highlights a robust platform for aminosugar nucleotide synthesis and reveals OleD Loki to be a proficient catalyst for U/TDP-aminosugar synthesis and utilization.
Co-reporter: Shanteri Singh;Dr. Nitin S. Nurkar ; Jon S. Thorson
ChemBioChem 2014 Volume 15( Issue 10) pp:1418-1421
Publication Date(Web):
DOI:10.1002/cbic.201402119
Abstract
Although bacterial iterative type I polyketide synthases are now known to participate in the biosynthesis of a small set of diverse natural products, the subsequent downstream modification of the resulting polyketide products is poorly understood. We report the functional characterization of the putative orsellinic acid C2-O-methyltransferase, which is involved in calicheamicin biosynthesis. This study suggests that C2-O-methylation precedes C3-hydroxylation/methylation and C5-iodination and requires a coenzyme A- or acyl carrier protein-bound substrate.
Co-reporter:Dr. Shanteri Singh;Dr. Jianjun Zhang;Tyler D. Huber;Manjula Sunkara;Katherine Hurley;Dr. Ral D. Goff;Dr. Guojun Wang;Wen Zhang; Chunming Liu; Jürgen Rohr; Steven G. VanLanen; Andrew J. Morris; Jon S. Thorson
Angewandte Chemie International Edition 2014 Volume 53( Issue 15) pp:
Publication Date(Web):
DOI:10.1002/anie.201308272
Abstract
A chemoenzymatic platform for the synthesis of S-adenosyl-L-methionine (SAM) analogues compatible with downstream SAM-utilizing enzymes is reported. Forty-four non-native S/Se-alkylated Met analogues were synthesized and applied to probing the substrate specificity of five diverse methionine adenosyltransferases (MATs). Human MAT II was among the most permissive of the MATs analyzed and enabled the chemoenzymatic synthesis of 29 non-native SAM analogues. As a proof of concept for the feasibility of natural product “alkylrandomization”, a small set of differentially-alkylated indolocarbazole analogues was generated by using a coupled hMAT2–RebM system (RebM is the sugar C4′-O-methyltransferase that is involved in rebeccamycin biosynthesis). The ability to couple SAM synthesis and utilization in a single vessel circumvents issues associated with the rapid decomposition of SAM analogues and thereby opens the door for the further interrogation of a wide range of SAM utilizing enzymes.
Co-reporter:Khaled A Shaaban, Shanteri Singh, Sherif I Elshahawi, Xiachang Wang, Larissa V Ponomareva, Manjula Sunkara, Gregory C Copley, James C Hower, Andrew J Morris, Madan K Kharel and Jon S Thorson
The Journal of Antibiotics 2014 67(3) pp:223-230
Publication Date(Web):November 13, 2013
DOI:10.1038/ja.2013.113
Venturicidin C (1), a new 20-membered macrolide along with the known venturicidins A (2) and B (3) were isolated from the crude extract of the Appalachian bacterial strain Streptomyces sp. TS-2-2. Additionally, nine other known compounds namely nocardamine, dehydroxynocardamine, desmethylenylnocardamine, ferrioxamine E, adenosine, riboflavin, cyclo(D)-trans-4-OH-Pro-(D)-Phe, cyclo(D)-Pro-(D)-Phe and N-(2-phenylethyl)-acetamide were also isolated and identified. The structure of the new macrolide 1 was elucidated by the cumulative analyses of NMR spectroscopy and HR-MS data. Complete NMR assignments for the known venturicidins A (2) and B (3) are also provided, for the first time, in this report. Venturicidins A–C did not inhibit the proliferation of A549 lung cancer cell line but all displayed potent antifungal activity.
Co-reporter:Yinan Zhang, Xiachang Wang, Manjula Sunkara, Qing Ye, Larissa V. Ponomereva, Qing-Bai She, Andrew J. Morris, and Jon S. Thorson
Organic Letters 2013 Volume 15(Issue 21) pp:5566-5569
Publication Date(Web):October 23, 2013
DOI:10.1021/ol4027649
An efficient diastereoselective oxa-Pictet–Spengler reaction strategy was developed to construct benzoisochroman diastereomers. The utility of the reaction was demonstrated in the context of both the total synthesis of naturally occurring pyranonaphthoquinones (+)-frenolicin B and epi-(+)-frenolicin B as well as a range of frenolicin precursor analogs. The method is versatile and offers exquisite stereocontrol and, as such, offers a synthetic advance for the synthesis of pyranonaphthoquinone analogs.
Co-reporter:Shanteri Singh, Aram Chang, Kate E. Helmich, Craig A. Bingman, Russell L. Wrobel, Emily T. Beebe, Shin-ichi Makino, David J. Aceti, Kevin Dyer, Greg L. Hura, Manjula Sunkara, Andrew J. Morris, George N. Phillips Jr., and Jon S. Thorson
ACS Chemical Biology 2013 Volume 8(Issue 7) pp:1632
Publication Date(Web):May 10, 2013
DOI:10.1021/cb400068k
Sugar methyltransferases (MTs) are an important class of tailoring enzymes that catalyze the transfer of a methyl group from S-adenosyl-l-methionine to sugar-based N-, C- and O-nucleophiles. While sugar N- and C-MTs involved in natural product biosynthesis have been found to act on sugar nucleotide substrates prior to a subsequent glycosyltransferase reaction, corresponding sugar O-methylation reactions studied thus far occur after the glycosyltransfer reaction. Herein we report the first in vitro characterization using 1H–13C-gHSQC with isotopically labeled substrates and the X-ray structure determination at 1.55 Å resolution of the TDP-3′-O-rhamnose-methyltransferase CalS11 from Micromonospora echinospora. This study highlights a unique NMR-based methyltransferase assay, implicates CalS11 to be a metal- and general acid/base-dependent O-methyltransferase, and as a first crystal structure for a TDP-hexose-O-methyltransferase, presents a new template for mechanistic studies and/or engineering.
Co-reporter:Maoquan Zhou ; Adel Hamza ; Chang-Guo Zhan ;Jon S. Thorson
Journal of Natural Products 2013 Volume 76(Issue 2) pp:279-286
Publication Date(Web):January 29, 2013
DOI:10.1021/np300890h
To explore the acceptor regioselectivity of OleD-catalyzed glucosylation, the products of OleD-catalyzed reactions with six structurally diverse acceptors flavones— (daidzein), isoflavones (flavopiridol), stilbenes (resveratrol), indole alkaloids (10-hydroxycamptothecin), and steroids (2-methoxyestradiol)—were determined. This study highlights the first synthesis of flavopiridol and 2-methoxyestradiol glucosides and confirms the ability of OleD to glucosylate both aromatic and aliphatic nucleophiles. In all cases, molecular dynamics simulations were consistent with the determined product distribution and suggest the potential to develop a virtual screening model to identify additional OleD substrates.
Co-reporter:Xiachang Wang ; Khaled A. Shaaban ; Sherif I. Elshahawi ; Larissa V. Ponomareva ; Manjula Sunkara ; Yinan Zhang ; Gregory C. Copley ; James C. Hower ; Andrew J. Morris ; Madan K. Kharel ;Jon S. Thorson
Journal of Natural Products 2013 Volume 76(Issue 8) pp:1441-1447
Publication Date(Web):August 14, 2013
DOI:10.1021/np400231r
Appalachian active coal fire sites were selected for the isolation of bacterial strains belonging to the class actinobacteria. A comparison of high-resolution electrospray ionization mass spectrometry (HRESIMS) and ultraviolet (UV) absorption profiles from isolate extracts to natural product databases suggested Streptomyces sp. RM-4-15 to produce unique metabolites. Four new pyranonaphthoquinones, frenolicins C–F (1–4), along with three known analogues, frenolicin (6), frenolicin B (7), and UCF76-A (8), were isolated from the fermentation of this strain. An additional new analogue, frenolicin G (5), along with two known compounds, deoxyfrenolicin (9) and UCF 13 (10), were isolated from the fermentation supplied with 18 mg/L of scandium chloride, the first example, to the best of our knowledge, wherein scandium chloride supplementation led to the confirmed production of new bacterial secondary metabolites. Structures 1–5 were elucidated on the basis of spectral analysis and chemical modification. While frenolicins are best known for their anticoccidial activity, the current study revealed compounds 6–9 to exhibit moderate cytotoxicity against the human lung carcinoma cell line (A549) and thereby extends the anticancer SAR for this privileged scaffold.
Co-reporter:Jianjun Zhang, Larissa V. Ponomareva, Karen Marchillo, Maoquan Zhou, David R. Andes, and Jon S. Thorson
Journal of Natural Products 2013 Volume 76(Issue 9) pp:1627-1636
Publication Date(Web):August 29, 2013
DOI:10.1021/np4003096
A set of 37 doxycycline neoglycosides were prepared, mediated via a C-9 alkoxyamino-glycyl-based spacer reminiscent of that of tigecycline. Subsequent in vitro antibacterial assays against representative drug-resistant Gram negative and Gram positive strains revealed a sugar-dependent activity profile and one doxycycline neoglycoside, the 2′-amino-α-d-glucoside conjugate, to rival that of the parent pharmacophore. In contrast, the representative tetracycline-susceptible strain E. coli 25922 was found to be relatively responsive to a range of doxycycline neoglycosides. This study also extends the use of aminosugars in the context of neoglycosylation via a simple two-step strategy anticipated to be broadly applicable for neoglycorandomization.
Co-reporter:Khaled A. Shaaban, Xiachang Wang, Sherif I. Elshahawi, Larissa V. Ponomareva, Manjula Sunkara, Gregory C. Copley, James C. Hower, Andrew J. Morris, Madan K. Kharel, and Jon S. Thorson
Journal of Natural Products 2013 Volume 76(Issue 9) pp:1619-1626
Publication Date(Web):August 15, 2013
DOI:10.1021/np400308w
Bacterial strains belonging to the class actinomycetes were isolated from the soil near a thermal vent of the Ruth Mullins coal fire (Appalachian Mountains of eastern Kentucky). High-resolution electrospray ionization mass spectrometry and ultraviolet absorption profiles of metabolites from one of the isolates (Streptomyces sp. RM-7-15) revealed the presence of a unique set of metabolites ultimately determined to be herbimycins D–F (1–3). In addition, herbimycin A (4), dihydroherbimycin A (TAN 420E) (7), and the structurally distinct antibiotic bicycylomycin were isolated from the crude extract of Streptomyces sp. RM-7-15. Herbimycins A and D–F (1–3) displayed comparable binding affinities to the Hsp90α. While the new analogues were found to be inactive in cancer cell cytotoxicity and antimicrobial assays, they may offer new insights in the context of nontoxic ansamycin-based Hsp90 inhibitors for the treatment of neurodegenerative disease.
Co-reporter:Richard W. Gantt;Pauline Peltier-Pain;Shanteri Singh;Jon S. Thorson;Maoquan Zhou
PNAS 2013 Volume 110 (Issue 19 ) pp:7648-7653
Publication Date(Web):2013-05-07
DOI:10.1073/pnas.1220220110
We described the integration of the general reversibility of glycosyltransferase-catalyzed reactions, artificial glycosyl
donors, and a high throughput colorimetric screen to enable the engineering of glycosyltransferases for combinatorial sugar
nucleotide synthesis. The best engineered catalyst from this study, the OleD Loki variant, contained the mutations P67T/I112P/T113M/S132F/A242I
compared with the OleD wild-type sequence. Evaluated against the parental sequence OleD TDP16 variant used for screening,
the OleD Loki variant displayed maximum improvements in kcat/Km of >400-fold and >15-fold for formation of NDP–glucoses and UDP–sugars, respectively. This OleD Loki variant also demonstrated
efficient turnover with five variant NDP acceptors and six variant 2-chloro-4-nitrophenyl glycoside donors to produce 30 distinct
NDP–sugars. This study highlights a convenient strategy to rapidly optimize glycosyltransferase catalysts for the synthesis
of complex sugar nucleotides and the practical synthesis of a unique set of sugar nucleotides.
Co-reporter:Shanteri Singh, George N. Phillips Jr. and Jon S. Thorson
Natural Product Reports 2012 vol. 29(Issue 10) pp:1201-1237
Publication Date(Web):12 Jun 2012
DOI:10.1039/C2NP20039B
Covering: up to 2012
The glycosylation of microbial natural products often dramatically influences the biological and/or pharmacological activities of the parental metabolite. Over the past decade, crystal structures of several enzymes involved in the biosynthesis and attachment of novel sugars found appended to natural products have emerged. In many cases, these studies have paved the way to a better understanding of the corresponding enzyme mechanism of action and have served as a starting point for engineering variant enzymes to facilitate to production of differentially-glycosylated natural products. This review specifically summarizes the structural studies of bacterial enzymes involved in biosynthesis of novel sugar nucleotides.
Co-reporter:Randal D. Goff and Jon S. Thorson
Organic Letters 2012 Volume 14(Issue 10) pp:2454-2457
Publication Date(Web):April 27, 2012
DOI:10.1021/ol300703z
The Veratrum alkaloid cyclopamine, an inhibitor of cancer stem cell growth, was used as a representative scaffold to evaluate the inhibitory impact of glycosylation with a group of nonmetabolic saccharides, such as d-threose. In a five-step divergent process, a 32-member glycoside library was created and assayed to determine that glycosides of such sugars notably improved the GI50 value of cyclopamine while metabolic sugars, such as d-glucose, did not.
Co-reporter:Maoquan Zhou, Yanpeng Hou, Adel Hamza, Chang-Guo Zhan, Tim S. Bugni, and Jon S. Thorson
Organic Letters 2012 Volume 14(Issue 21) pp:5424-5427
Publication Date(Web):October 18, 2012
DOI:10.1021/ol3024924
The potential of a uniquely permissive engineered glycosyltransferase (OleD ASP) as a catalyst for steroid glycosylation is highlighted. The ability of OleD ASP to glucosylate a range of cardenolides and bufadienolides was assessed using a rapid LC-UV/MS-SPE-NMR analytical platform. While a bias toward OleD-catalyzed C3 monoglucosylation was observed, subtle alterations of the steroidal architecture, in some cases, invoked diglucosylation or, in one case (digoxigenin), C12 glucosylation. This latter case represents the first, and highly efficient, synthesis of digoxigenin 12-O-β-d-glucoside.
Co-reporter:Pauline Peltier-Pain, Karen Marchillo, Maoquan Zhou, David R. Andes, and Jon S. Thorson
Organic Letters 2012 Volume 14(Issue 19) pp:5086-5089
Publication Date(Web):September 17, 2012
DOI:10.1021/ol3023374
A two-step strategy for disaccharide modulation using vancomycin as a model is reported. The strategy relies upon a glycosyltransferase-catalyzed ‘reverse’ reaction to enable the facile attachment of an alkoxyamine-bearing sugar to the vancomycin core. Neoglycosylation of the corresponding aglycon led to a novel set of vancomycin 1,6-disaccharide variants. While the in vitro antibacterial properties of corresponding vancomycin 1,6-disaccharide analogs were equipotent to the parent antibiotic, the chemoenzymatic method presented is expected to be broadly applicable.
Co-reporter:Tyler D Huber, Brooke R Johnson, Jianjun Zhang, Jon S Thorson
Current Opinion in Biotechnology (December 2016) Volume 42() pp:189-197
Publication Date(Web):1 December 2016
DOI:10.1016/j.copbio.2016.07.005
•AdoMet is one of the most essential cosubstrates in nature.•Practical access to AdoMet analogs enables new tools, technologies, leads and discoveries.•Both synthetic and chemoenzymatic strategies for AdoMet production have been advanced.•Chemoenzymatic strategies set the stage for cell-based or whole animal applications.•Bioorthogonal catalyst/AdoMet pairings are anticipated to have a dramatic impact.S-Adenosyl-l-methionine (AdoMet) is an essential enzyme cosubstrate in fundamental biology with an expanding range of biocatalytic and therapeutic applications. In recent years, technologies enabling the synthesis and utilization of novel functional AdoMet surrogates have rapidly advanced. Developments highlighted within this brief review include improved syntheses of AdoMet analogs, unique S-adenosyl-l-methionine isosteres with enhanced stability, and corresponding applications in epigenetics, proteomics and natural product/small molecule diversification (‘alkylrandomization’).Download high-res image (72KB)Download full-size image
Co-reporter:Sherif I. Elshahawi, Khaled A. Shaaban, Madan K. Kharel and Jon S. Thorson
Chemical Society Reviews 2015 - vol. 44(Issue 21) pp:NaN7697-7697
Publication Date(Web):2015/03/04
DOI:10.1039/C4CS00426D
A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.
![cyclo[-L-Ile-D-Ile-L-Lys-L-Ile-D-Phe-D-Leu-L-Ile-D-Ala-]](http://img.cochemist.com/ccimg/1444100/1444002-12-3.png)
![cyclo[-L-Ile-D-Ile-L-Lys-L-Ile-D-Phe-D-Leu-L-Ile-D-Ala-]](http://img.cochemist.com/ccimg/1444100/1444002-12-3_b.png)
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![D-GLUCOSE, 6-DEOXY-6-[(1-OXODECYL)AMINO]-](http://img.cochemist.com/ccimg/916500/916461-03-5.png)
![D-GLUCOSE, 6-DEOXY-6-[(1-OXODECYL)AMINO]-](http://img.cochemist.com/ccimg/916500/916461-03-5_b.png)
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![3-(3-HYDROXYPROPYL)-8-[(E)-2-(3-METHOXYPHENYL)ETHENYL]-7-METHYL-1-PROP-2-YNYLPURINE-2,6-DIONE](http://img.cochemist.com/data/images/261717-18-4.png)
![3-(3-HYDROXYPROPYL)-8-[(E)-2-(3-METHOXYPHENYL)ETHENYL]-7-METHYL-1-PROP-2-YNYLPURINE-2,6-DIONE](http://img.cochemist.com/data/images/261717-18-4_b.png)
![D-Glucose, 2-deoxy-2-[[(2-propenyloxy)carbonyl]amino]-](http://img.cochemist.com/ccimg/115500/115491-95-7.png)
![D-Glucose, 2-deoxy-2-[[(2-propenyloxy)carbonyl]amino]-](http://img.cochemist.com/ccimg/115500/115491-95-7_b.png)
![4,21-Dioxabicyclo[15.3.1]heneicosa-9,15,18-trien-3-one,11-[[3-O-(aminocarbonyl)-2,6-dideoxy-b-D-arabino-hexopyranosyl]oxy]-1,7-dihydroxy-5-[(1R,3R,4S,5S)-4-hydroxy-1,3,5-trimethyl-6-oxooctyl]-6,8,16,18-tetramethyl-,(1R,5R,6R,8S,9E,11R,15E,17R)- (9CI)](http://img.cochemist.com/ccimg/113300/113204-43-6.png)
![4,21-Dioxabicyclo[15.3.1]heneicosa-9,15,18-trien-3-one,11-[[3-O-(aminocarbonyl)-2,6-dideoxy-b-D-arabino-hexopyranosyl]oxy]-1,7-dihydroxy-5-[(1R,3R,4S,5S)-4-hydroxy-1,3,5-trimethyl-6-oxooctyl]-6,8,16,18-tetramethyl-,(1R,5R,6R,8S,9E,11R,15E,17R)- (9CI)](http://img.cochemist.com/ccimg/113300/113204-43-6_b.png)
![Butanoic acid, 3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-, ethyl ester, (3R)-](http://img.cochemist.com/ccimg/109800/109715-46-0.png)
![Butanoic acid, 3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-, ethyl ester, (3R)-](http://img.cochemist.com/ccimg/109800/109715-46-0_b.png)
![a-L-Talofuranuronamide,1-deoxy-5-O-[4-deoxy-N-[(3S)-hexahydro-2-oxo-1H-azepin-3-yl]-b-L-erythro-hex-4-enopyranuronamidosyl]-1-(3,4-dihydro-2,4-dioxo-1(2H)-pyrimidinyl)-3-O-methyl-](http://img.cochemist.com/ccimg/102800/102770-00-3.png)
![a-L-Talofuranuronamide,1-deoxy-5-O-[4-deoxy-N-[(3S)-hexahydro-2-oxo-1H-azepin-3-yl]-b-L-erythro-hex-4-enopyranuronamidosyl]-1-(3,4-dihydro-2,4-dioxo-1(2H)-pyrimidinyl)-3-O-methyl-](http://img.cochemist.com/ccimg/102800/102770-00-3_b.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,1-chloro-13-[6-O-[2,4-dideoxy-4-(methylamino)-a-L-threo-pentopyranosyl]-4-O-methyl-b-D-glucopyranosyl]-12,13-dihydro-6-methyl-](http://img.cochemist.com/ccimg/102700/102644-20-2.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,1-chloro-13-[6-O-[2,4-dideoxy-4-(methylamino)-a-L-threo-pentopyranosyl]-4-O-methyl-b-D-glucopyranosyl]-12,13-dihydro-6-methyl-](http://img.cochemist.com/ccimg/102700/102644-20-2_b.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,13-[6-O-(4-amino-2,4-dideoxy-a-L-threo-pentopyranosyl)-4-O-methyl-b-D-glucopyranosyl]-1-chloro-12,13-dihydro-6-methyl-](http://img.cochemist.com/ccimg/102700/102644-19-9.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,13-[6-O-(4-amino-2,4-dideoxy-a-L-threo-pentopyranosyl)-4-O-methyl-b-D-glucopyranosyl]-1-chloro-12,13-dihydro-6-methyl-](http://img.cochemist.com/ccimg/102700/102644-19-9_b.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,12-[6-O-[2,4-dideoxy-4-(methylamino)-a-L-threo-pentopyranosyl]-4-O-methyl-b-D-glucopyranosyl]-12,13-dihydro-6-methyl-](http://img.cochemist.com/ccimg/102700/102622-96-8.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,12-[6-O-[2,4-dideoxy-4-(methylamino)-a-L-threo-pentopyranosyl]-4-O-methyl-b-D-glucopyranosyl]-12,13-dihydro-6-methyl-](http://img.cochemist.com/ccimg/102700/102622-96-8_b.png)
![5-(5-ethyl-4-hydroxy-1,3-dimethyl-6-oxooctyl)-1,7-dihydroxy-6,8,16,18-tetramethyl-3-oxo-4,21-dioxabicyclo[15.3.1]henicosa-9,15,18-trien-11-yl 3-O-carbamoyl-2,6-dideoxyhexopyranoside](http://img.cochemist.com/ccimg/97500/97430-31-4.png)
![5-(5-ethyl-4-hydroxy-1,3-dimethyl-6-oxooctyl)-1,7-dihydroxy-6,8,16,18-tetramethyl-3-oxo-4,21-dioxabicyclo[15.3.1]henicosa-9,15,18-trien-11-yl 3-O-carbamoyl-2,6-dideoxyhexopyranoside](http://img.cochemist.com/ccimg/97500/97430-31-4_b.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,1,11-dichloro-12,13-dihydro-12-(4-O-methyl-b-D-glucopyranosyl)-](http://img.cochemist.com/ccimg/94000/93908-02-2.png)
![5H-Indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione,1,11-dichloro-12,13-dihydro-12-(4-O-methyl-b-D-glucopyranosyl)-](http://img.cochemist.com/ccimg/94000/93908-02-2_b.png)
![4,21-Dioxabicyclo[15.3.1]heneicosa-9,15,18-trien-3-one, 1,7,11-trihydroxy-5-[(1R,3R,4S,5S)-4-hydroxy-1,3,5-trimethyl-6-oxooctyl]-6,8,16,18-](/data/chemimg/2017400/87084-45-5.png)
![4,21-Dioxabicyclo[15.3.1]heneicosa-9,15,18-trien-3-one, 1,7,11-trihydroxy-5-[(1R,3R,4S,5S)-4-hydroxy-1,3,5-trimethyl-6-oxooctyl]-6,8,16,18-](/data/chemimg/2017400/87084-45-5_b.png)
![2H-Furo[3,2-b]naphtho[2,3-d]pyran-2,6,11-trione,3,3a,5,11b-tetrahydro-7-hydroxy-5-propyl-, (3aR,5R,11bR)-](http://img.cochemist.com/ccimg/69000/68930-68-7.png)
![2H-Furo[3,2-b]naphtho[2,3-d]pyran-2,6,11-trione,3,3a,5,11b-tetrahydro-7-hydroxy-5-propyl-, (3aR,5R,11bR)-](http://img.cochemist.com/ccimg/69000/68930-68-7_b.png)
![3',7-dihydroxy-6'-methyl-2,6,11-trioxo-2,3,3',3a,4',5',6,6',11,11b-decahydrospiro[benzo[g]furo[3,2-c]isochromene-5,2'-pyran]-4'-yl acetate](http://img.cochemist.com/ccimg/59600/59554-11-9.png)
![3',7-dihydroxy-6'-methyl-2,6,11-trioxo-2,3,3',3a,4',5',6,6',11,11b-decahydrospiro[benzo[g]furo[3,2-c]isochromene-5,2'-pyran]-4'-yl acetate](http://img.cochemist.com/ccimg/59600/59554-11-9_b.png)
![18H-16a,19-Metheno-16aH-benzo[e]naphtho[2,1-m][1,4]dioxacyclopentadecin-14-carboxylicacid, 4-[[4-O-[3-O-(3-chloro-6-methoxy-2-methylbenzoyl)-2,6-dideoxy-b-D-arabino-hexopyranosyl]-2,6-dideoxy-b-D-arabino-hexopyranosyl]oxy]-1,2,3,4,4a,6a,7,8,9,10,12a,15,16,21,21a,21b-hexadecahydro-22-hydroxy-15,21a-dimethyl-18,21-dioxo-,(4S,4aS,6aR,11E,12aR,15R,16aS,21aR,21bR)-](http://img.cochemist.com/ccimg/34800/34707-92-1.png)
![18H-16a,19-Metheno-16aH-benzo[e]naphtho[2,1-m][1,4]dioxacyclopentadecin-14-carboxylicacid, 4-[[4-O-[3-O-(3-chloro-6-methoxy-2-methylbenzoyl)-2,6-dideoxy-b-D-arabino-hexopyranosyl]-2,6-dideoxy-b-D-arabino-hexopyranosyl]oxy]-1,2,3,4,4a,6a,7,8,9,10,12a,15,16,21,21a,21b-hexadecahydro-22-hydroxy-15,21a-dimethyl-18,21-dioxo-,(4S,4aS,6aR,11E,12aR,15R,16aS,21aR,21bR)-](http://img.cochemist.com/ccimg/34800/34707-92-1_b.png)
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![4,21-Dioxabicyclo[15.3.1]heneicosa-9,15,18-trien-3-one,11-[[3-O-(aminocarbonyl)-2,6-dideoxy-b-D-arabino-hexopyranosyl]oxy]-1-hydroxy-5-[(1R,3R,4S,5S)-4-hydroxy-1,3,5-trimethyl-6-oxooctyl]-6,8,16,18-tetramethyl-,(1R,5S,6R,8R,9E,11R,15E,17R)- (9CI)](http://img.cochemist.com/ccimg/33600/33538-71-5_b.png)
![Butanoic acid, 2-amino-4-[(phenylmethyl)seleno]-, (S)-](http://img.cochemist.com/ccimg/19700/19635-25-7.png)
![Butanoic acid, 2-amino-4-[(phenylmethyl)seleno]-, (S)-](http://img.cochemist.com/ccimg/19700/19635-25-7_b.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8_b.png)
![4H-Anthra[1,2-b]pyran-4,7,12-trione,10-[4-O-acetyl-2,3,6-trideoxy-3-(dimethylamino)-3-C-methyl-a-L-lyxo-hexopyranosyl]-11-hydroxy-5-methyl-2-[2-methyl-3-(1-propenyl)oxiranyl]-8-[2,3,6-trideoxy-3-(dimethylamino)-b-D-arabino-hexopyranosyl]- (9CI)](http://img.cochemist.com/ccimg/11100/11016-27-6.png)
![4H-Anthra[1,2-b]pyran-4,7,12-trione,10-[4-O-acetyl-2,3,6-trideoxy-3-(dimethylamino)-3-C-methyl-a-L-lyxo-hexopyranosyl]-11-hydroxy-5-methyl-2-[2-methyl-3-(1-propenyl)oxiranyl]-8-[2,3,6-trideoxy-3-(dimethylamino)-b-D-arabino-hexopyranosyl]- (9CI)](http://img.cochemist.com/ccimg/11100/11016-27-6_b.png)
![7H-Pyrrolo[2,3-d]pyrimidin-4-amine,7-[5-O-[hydroxy[[hydroxy(phosphonooxy)phosphinyl]oxy]phosphinyl]-b-D-ribofuranosyl]-](http://img.cochemist.com/ccimg/10100/10058-66-9.png)
![7H-Pyrrolo[2,3-d]pyrimidin-4-amine,7-[5-O-[hydroxy[[hydroxy(phosphonooxy)phosphinyl]oxy]phosphinyl]-b-D-ribofuranosyl]-](http://img.cochemist.com/ccimg/10100/10058-66-9_b.png)
![Pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro-3-(phenylmethyl)-, (3S,8aS)-](http://img.cochemist.com/ccimg/3800/3705-26-8.png)
![Pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro-3-(phenylmethyl)-, (3S,8aS)-](http://img.cochemist.com/ccimg/3800/3705-26-8_b.png)
![(3S-trans)-hexahydro-3-isobutylpyrrolo[1,2-a]pyrazine-1,4-dione](http://img.cochemist.com/ccimg/2900/2873-36-1.png)
![(3S-trans)-hexahydro-3-isobutylpyrrolo[1,2-a]pyrazine-1,4-dione](http://img.cochemist.com/ccimg/2900/2873-36-1_b.png)
![[hydroxy-[[(2r,3s,5r)-3-hydroxy-5-(5-methyl-2,4-dioxopyrimidin-1-yl)oxolan-2-yl]methoxy]phosphoryl] [(2r,3r,4s,5s,6r)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl] Hydrogen Phosphate](http://img.cochemist.com/ccimg/2200/2196-62-5.png)
![[hydroxy-[[(2r,3s,5r)-3-hydroxy-5-(5-methyl-2,4-dioxopyrimidin-1-yl)oxolan-2-yl]methoxy]phosphoryl] [(2r,3r,4s,5s,6r)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl] Hydrogen Phosphate](http://img.cochemist.com/ccimg/2200/2196-62-5_b.png)
![Carbamic acid,N-[(1R,4Z,8S,13E)-8-[[4,6-dideoxy-4-[[[2,6-dideoxy-4-S-[4-[(6-deoxy-3-O-methyl-a-L-mannopyranosyl)oxy]-3-iodo-5,6-dimethoxy-2-methylbenzoyl]-4-thio-b-D-ribo-hexopyranosyl]oxy]amino]-2-O-[2,4-dideoxy-4-(ethylamino)-3-O-methyl-a-L-threo-pentopyranosyl]-b-D-glucopyranosyl]oxy]-1-hydroxy-13-[2-(methyltrithio)ethylidene]-11-oxobicyclo[7.3.1]trideca-4,9-diene-2,6-diyn-10-yl]-,methyl ester](http://img.cochemist.com/ccimg/108300/108212-75-5.png)
![Carbamic acid,N-[(1R,4Z,8S,13E)-8-[[4,6-dideoxy-4-[[[2,6-dideoxy-4-S-[4-[(6-deoxy-3-O-methyl-a-L-mannopyranosyl)oxy]-3-iodo-5,6-dimethoxy-2-methylbenzoyl]-4-thio-b-D-ribo-hexopyranosyl]oxy]amino]-2-O-[2,4-dideoxy-4-(ethylamino)-3-O-methyl-a-L-threo-pentopyranosyl]-b-D-glucopyranosyl]oxy]-1-hydroxy-13-[2-(methyltrithio)ethylidene]-11-oxobicyclo[7.3.1]trideca-4,9-diene-2,6-diyn-10-yl]-,methyl ester](http://img.cochemist.com/ccimg/108300/108212-75-5_b.png)
![D-neo-Inositol,5-deoxy-5-[[(2E)-3-[4-[(6-deoxy-a-L-xylo-hexofuranos-5-ulos-1-yl)oxy]-3-hydroxyphenyl]-2-methyl-1-oxo-2-propen-1-yl]amino]-1,2-O-methylene-](http://img.cochemist.com/ccimg/75100/75081-92-4.png)
![D-neo-Inositol,5-deoxy-5-[[(2E)-3-[4-[(6-deoxy-a-L-xylo-hexofuranos-5-ulos-1-yl)oxy]-3-hydroxyphenyl]-2-methyl-1-oxo-2-propen-1-yl]amino]-1,2-O-methylene-](http://img.cochemist.com/ccimg/75100/75081-92-4_b.png)
![13,22-dihydroxy-8,14-dimethoxy-4,10,12,16-tetramethyl-3,19,20-trioxo-2-azabicyclo[16.3.1]docosa-1(21),4,6,10,18(22)-pentaen-9-yl carbamate](http://img.cochemist.com/ccimg/52800/52762-28-4.png)
![13,22-dihydroxy-8,14-dimethoxy-4,10,12,16-tetramethyl-3,19,20-trioxo-2-azabicyclo[16.3.1]docosa-1(21),4,6,10,18(22)-pentaen-9-yl carbamate](http://img.cochemist.com/ccimg/52800/52762-28-4_b.png)
![D-neo-Inositol,5-deoxy-5-[[(2E)-3-[4-[(6-deoxy-b-D-arabino-hexofuranos-5-ulos-1-yl)oxy]-3-hydroxyphenyl]-2-methyl-1-oxo-2-propen-1-yl]amino]-1,2-O-methylene-](http://img.cochemist.com/ccimg/6400/6379-56-2.png)
![D-neo-Inositol,5-deoxy-5-[[(2E)-3-[4-[(6-deoxy-b-D-arabino-hexofuranos-5-ulos-1-yl)oxy]-3-hydroxyphenyl]-2-methyl-1-oxo-2-propen-1-yl]amino]-1,2-O-methylene-](http://img.cochemist.com/ccimg/6400/6379-56-2_b.png)
