This document describes the synthesis of seven new analogues of the macrocyclic peptide sanguinamide B (SanB) and testing of their ability to inhibit protein synthesis in cancer cells. The analogues were designed by altering the amino acids at positions I and III of the SanB backbone, inverting stereochemistry at position III, and changing the protecting group on lysine. All analogues were tested for cytotoxicity against colon cancer cell lines and ability to inhibit protein synthesis. The lead compound with an IC50 of 15.9 μM against colon cancer cells contained an N6-carboxybenzyl-lysine at position I. This establishes the importance of this moiety for biological activity.
This document summarizes research on the topology of the multidrug transporter EmrE. The authors found that EmrE exists as a parallel homodimer through chemical cross-linking experiments. A cross-linked dimer was purified and shown to be fully functional, transporting substrates and binding ligands with similar kinetics as the non-cross-linked dimer. This supports a parallel topology for EmrE and suggests the antiparallel orientation seen in crystal structures may be due to crystal packing effects. Detergents used in crystallization were found to increase the monomer fraction, and the authors propose antiparallel monomers seen in crystals form from these monomers.
This document summarizes a study that found neomycin, an aminoglycoside antibiotic, is capable of binding tightly to single-stranded poly(A) RNA with a Kd in the micromolar range. Circular dichroism experiments showed neomycin forms a complex with poly(A) and increases its melting temperature from 44°C to 61°C, suggesting neomycin strongly stabilizes the poly(A) duplex. Isothermal titration calorimetry found neomycin binds oligo(A)30 with a binding constant of 5.3×10^6 M^-1 and a stoichiometry of one neomycin per 10 adenine bases. This study demonstrates that neomycin can target single
The document describes the synthesis and characterization of 9-anilinoacridine derivatives substituted with oxazine moieties to evaluate their antioxidant and anticancer activities. A series of 9-anilinoacridines were synthesized by reacting 1-[4-(acridin-9-ylamino)phenyl]ethanone with various aldehydes using Claisen-Schmidt condensation. The structures of the synthesized compounds were confirmed using spectroscopic techniques like IR, NMR, mass spectrometry. The compounds were evaluated for their antioxidant activity by hydrogen peroxide and superoxide radical scavenging assays. Their anticancer potential was studied against Dalton's lymphoma ascites cell line using trypan blue dye exclusion and
This document describes a new method called polymer-aided stereodivergent synthesis (PASS) that allows the simultaneous preparation of both enantiomers of a chiral compound in discrete form. The key steps are: (1) A cyclization reaction on a polymer-supported quasi-meso substrate leads to the formation of quasi-enantiomers, with one immobilized on the polymer and the other free in solution. (2) Treatment with nucleophiles converts the quasi-enantiomers into the desired enantiomers. This new method was demonstrated through the synthesis of optically pure oxazolidinone enantiomers.
Voss et al. - 2006 - Identification and characterization of riproximin,Cristina Voss
1. Researchers purified and characterized a new type II ribosome-inactivating protein called riproximin from the plant Ximenia americana.
2. Riproximin was found to potently inhibit protein synthesis and cancer cell growth in vitro with picomolar IC50 values, and inhibit tumor growth in vivo after intraperitoneal or oral administration in a rat model.
3. The researchers identified the riproximin protein through mass spectrometry and cDNA sequencing. Molecular modeling showed riproximin has structural similarity to other toxic type II ribosome-inactivating proteins and an active site for its RNA N-glycosidase activity.
1) Chiral phosphoric acid catalyst PA-1 promotes the highly enantioselective ring-opening of meso-aziridines with a variety of functionalized aromatic thiols. The reaction proceeds in good yields and with up to 97% enantiomeric excess.
2) The reaction tolerates a wide range of substituted thiols, including those with electron-donating and -withdrawing groups, as well as heteroaromatic thiols. Alkyl thiols perform less well.
3) Different meso-aziridine substrates are also suitable, including those with fused ring systems or acyclic substituents. The reaction provides a simple method for the
1. ATP is often described as the universal energy currency of cells. It couples catabolic and anabolic processes.
2. The products formed at the end of stage 1 in the light dependent reactions of photosynthesis are oxygen, ATP and reduced NADP.
3. Glycolysis requires glucose, the appropriate enzymes and ATP.
The bc1 complex provides reduced cytochrome c to either the aa3 or cbb3 oxidases depending on oxygen conditions in R. sphaeroides. Strain BC-17 cannot photosynthesize due to lack of bc1 complex reducing cbb3. Some H217 mutations in the QI site can photosynthesize with DMSO but revert or are lethal without it. Future work should introduce H217 mutations into a DorR-/PpsR- background to uncouple effects on bc1 from changes to photosystem expression levels.
This document summarizes research on the topology of the multidrug transporter EmrE. The authors found that EmrE exists as a parallel homodimer through chemical cross-linking experiments. A cross-linked dimer was purified and shown to be fully functional, transporting substrates and binding ligands with similar kinetics as the non-cross-linked dimer. This supports a parallel topology for EmrE and suggests the antiparallel orientation seen in crystal structures may be due to crystal packing effects. Detergents used in crystallization were found to increase the monomer fraction, and the authors propose antiparallel monomers seen in crystals form from these monomers.
This document summarizes a study that found neomycin, an aminoglycoside antibiotic, is capable of binding tightly to single-stranded poly(A) RNA with a Kd in the micromolar range. Circular dichroism experiments showed neomycin forms a complex with poly(A) and increases its melting temperature from 44°C to 61°C, suggesting neomycin strongly stabilizes the poly(A) duplex. Isothermal titration calorimetry found neomycin binds oligo(A)30 with a binding constant of 5.3×10^6 M^-1 and a stoichiometry of one neomycin per 10 adenine bases. This study demonstrates that neomycin can target single
The document describes the synthesis and characterization of 9-anilinoacridine derivatives substituted with oxazine moieties to evaluate their antioxidant and anticancer activities. A series of 9-anilinoacridines were synthesized by reacting 1-[4-(acridin-9-ylamino)phenyl]ethanone with various aldehydes using Claisen-Schmidt condensation. The structures of the synthesized compounds were confirmed using spectroscopic techniques like IR, NMR, mass spectrometry. The compounds were evaluated for their antioxidant activity by hydrogen peroxide and superoxide radical scavenging assays. Their anticancer potential was studied against Dalton's lymphoma ascites cell line using trypan blue dye exclusion and
This document describes a new method called polymer-aided stereodivergent synthesis (PASS) that allows the simultaneous preparation of both enantiomers of a chiral compound in discrete form. The key steps are: (1) A cyclization reaction on a polymer-supported quasi-meso substrate leads to the formation of quasi-enantiomers, with one immobilized on the polymer and the other free in solution. (2) Treatment with nucleophiles converts the quasi-enantiomers into the desired enantiomers. This new method was demonstrated through the synthesis of optically pure oxazolidinone enantiomers.
Voss et al. - 2006 - Identification and characterization of riproximin,Cristina Voss
1. Researchers purified and characterized a new type II ribosome-inactivating protein called riproximin from the plant Ximenia americana.
2. Riproximin was found to potently inhibit protein synthesis and cancer cell growth in vitro with picomolar IC50 values, and inhibit tumor growth in vivo after intraperitoneal or oral administration in a rat model.
3. The researchers identified the riproximin protein through mass spectrometry and cDNA sequencing. Molecular modeling showed riproximin has structural similarity to other toxic type II ribosome-inactivating proteins and an active site for its RNA N-glycosidase activity.
1) Chiral phosphoric acid catalyst PA-1 promotes the highly enantioselective ring-opening of meso-aziridines with a variety of functionalized aromatic thiols. The reaction proceeds in good yields and with up to 97% enantiomeric excess.
2) The reaction tolerates a wide range of substituted thiols, including those with electron-donating and -withdrawing groups, as well as heteroaromatic thiols. Alkyl thiols perform less well.
3) Different meso-aziridine substrates are also suitable, including those with fused ring systems or acyclic substituents. The reaction provides a simple method for the
1. ATP is often described as the universal energy currency of cells. It couples catabolic and anabolic processes.
2. The products formed at the end of stage 1 in the light dependent reactions of photosynthesis are oxygen, ATP and reduced NADP.
3. Glycolysis requires glucose, the appropriate enzymes and ATP.
The bc1 complex provides reduced cytochrome c to either the aa3 or cbb3 oxidases depending on oxygen conditions in R. sphaeroides. Strain BC-17 cannot photosynthesize due to lack of bc1 complex reducing cbb3. Some H217 mutations in the QI site can photosynthesize with DMSO but revert or are lethal without it. Future work should introduce H217 mutations into a DorR-/PpsR- background to uncouple effects on bc1 from changes to photosystem expression levels.
This document describes the design, synthesis, and evaluation of a series of 1,3-disubstituted pyrrolo[2,3-b]quinoxalines as potential inhibitors of phosphodiesterase 4 (PDE4) and cancer cell growth. A ligand- and phase transfer catalyst-free intramolecular Heck reaction was used to synthesize the target compounds. Some compounds showed significant inhibition of PDE4B and growth inhibition of oral cancer cells in vitro. They also showed acceptable safety profiles in zebrafish embryos, but no apoptosis was observed. The goal was to develop PDE4 inhibitors that do not inhibit luciferase, which could produce false positives in assays.
This summary provides the key details about the document in 3 sentences:
The document describes the synthesis of new triciribine analogues as potential anti-HCV agents. Ten new β-D-ribofuranosyl and 20-β-C-methyl-β-D-ribofuranosyl triciribine derivatives were synthesized with various N4 and 6-N substituents. Some of the new compounds showed interesting anti-HCV activity with low cytotoxicity based on inhibitory studies in the HCV replicon assay.
1. The document describes the design and synthesis of molecules that mimic the natural selectin ligand sialyl Lewis X (sLeX) to function as selectin antagonists.
2. Key modifications to the sLeX structure included replacing the GlcNAc saccharide unit with an acyclic tether, and installing benzoate groups at different positions on the galactose and fucose units.
3. The new molecules were evaluated for their ability to inhibit selectin interactions using assays with E-selectin and P-selectin. Compounds with benzoate groups at both C2 and C4 positions on galactose showed the highest potency as selectin antagonists.
1. A biochemical reaction network model is developed to explore APP-C99 homodimer formation and its binding to cholesterol, which are believed to play roles in Alzheimer's disease.
2. The model consists of kinetic equations that capture the association and dissociation of APP-C99 monomers, dimers, and APP-C99 bound to cholesterol.
3. The model is parameterized using experimental data and simulations of APP-C99 and cholesterol diffusion, and solved using particle-based and stochastic simulations.
Switching Off and On the Supramolecular Chiral Memory in PorphyrinAngela Mammana
This document summarizes research on switching the chiral memory in porphyrin assemblies on and off. The researchers designed a system using tetra-cationic and tetra-anionic porphyrins that form chiral supramolecular complexes when mixed in the presence of a chiral template, like an amino acid. This complex retains its chirality even after removing the template. The researchers found they could cycle the complex between "written" and "erased" states by turning the electrostatic interactions on and off via protonation/deprotonation. Protonation induces aggregation and chirality, while raising the pH leads to disassembly and loss of chirality, but chiral "seeds" allow reassembly of the
Two new classes of potent antimalarial compounds, 4-amidinoquinoline (4-AMQ) and 10-amidinobenzonaphthyridine (10-AMB) derivatives, were discovered that displayed high activity in vitro and in vivo against Plasmodium falciparum. The best analog, WR910397, showed nanomolar potency against three Pf clones, low inhibition of the hERG potassium channel, no mutagenicity, and cured 5 out of 5 mice infected with P. berghei at a dose of 15 mpk x 3. These results indicate that 4-AMQ and 10-AMB derivatives are promising candidates for developing new antimalarial drugs with potential advantages over
Synthesis and Catalytic Application of Chiral 1,1′-Bi-2-naphtholand Biphenant...DrMAdamSayah
Synthesis and Catalytic Application of Chiral 1,1′-Bi-2-naphtholand Biphenanthrol-Based Pincer Complexes- Selective Allylation of Sulfonimines with Allyl Stannane and Allyl Trifluoroborate
This study found that the yeast LEA-like protein HSP 12 is located on the plasma membrane. Immunogold labeling observed HSP 12 on the external side of the plasma membrane in stationary phase yeast. HSP 12 was found to protect liposomal membrane integrity during desiccation, acting similarly to trehalose. Protection was only observed with positively charged liposomes, indicating an electrostatic interaction between HSP 12 and membranes. Yeast lacking HSP 12 were less able to grow in ethanol-containing media, and HSP 12 conferred increased liposomal membrane integrity in the presence of ethanol.
This document contains 50 multiple choice questions related to biology, chemistry, and genetics. The questions cover a range of topics including enzyme kinetics, genetics, cellular processes, and metabolic pathways. For each question, four answer options are provided and only one answer is correct. All 50 questions must be answered.
tuning the pH Response of i-Motif DNA Oligonucleotides_Lannes_et_al-2015-Chem...saheli halder
This document discusses tuning the pH response of i-motif DNA oligonucleotides. The authors introduced 5-methylcytosines (5-MeC) and 5-bromocytosines (5-BrC) into the human telomeric i-motif sequence to shift its pH response range. They found that 5-MeC shifted the pH response towards more basic values, while 5-BrC shifted it towards more acidic values. Additionally, lengthening the sequence shifted the pH response in a more basic direction. The modifications did not thermally destabilize the i-motifs. 5-BrC substitution led to a ten-fold increase in folding kinetics compared to the other sequences.
1. The study examines how the substrate L-serine interacts with and stabilizes the active site of serine hydroxymethyltransferase (SHMT) enzymes from sheep liver and E. coli.
2. Results show L-serine enhances the thermal stability of both SHMT enzymes, increasing their apparent melting temperatures. Binding studies also indicate L-serine induces conformational changes in the enzymes without altering their overall structure.
3. The conformational changes upon L-serine binding, monitored by various spectroscopic methods, suggest L-serine compacts the enzyme structure, leading to increased thermal stability.
This document summarizes the discovery and optimization of novel phenylalanine diamide inhibitors of Factor XIa (FXIa). Exploration of substituents on the P1', P2', and P1 positions led to the identification of compound 21, which demonstrated high affinity for FXIa, good potency in clotting assays, selectivity over other serine proteases, and efficacy in a rabbit thrombosis model. X-ray crystallography provided insights into key interactions between optimized compounds and residues in the FXIa active site.
This study used NMR spectroscopy to measure hydrogen exchange rates of backbone amide protons in two disordered proteins, a-synuclein and FlgM, in buffer and inside Escherichia coli cells. The rates were similar in buffer and cells, and close to rates predicted from studies of unstructured peptides. This suggests that true disorder can persist inside the crowded cellular interior, and that weak interactions between proteins and macromolecules in cells do not necessarily affect intrinsic exchange rates. However, the C-terminal region of FlgM showed some evidence of transient structure formation in buffer that was not observed inside cells.
This document contains a series of questions about aromatic compounds and electrophilic aromatic substitution reactions. It asks the reader to identify aromatic compounds, predict products of various substitution reactions involving benzene and related aromatic rings, explain directing effects of different substituents, and draw resonance structures of arenium ions formed in electrophilic aromatic substitution. The questions cover topics such as naming compounds, determining substituent effects, predicting reaction mechanisms, and requiring multi-step synthesis of aromatic compounds.
Enzyme Discovery for Natural Product BiosynthesisHongnan Cao
A poster presentation of collaborative work on the NIH funded project of Enzyme Discovery for Natural Product Biosynthesis at 2015 American Crystallography Association Meeting at Philadelphia, PA. Thanks to Rice University, University of Wisconsin-Madison, The Scripps Research Institute, University of Kentucky, The Midwest Center for Structural Genomics, The Northeast Center for Structural Genomics, APS synchrotron at Argonne National Lab
This document describes research into developing a potent and selective inhibitor of 11b-hydroxysteroid dehydrogenase type 1 (11b-HSD1) for the treatment of type 2 diabetes. The researchers synthesized various adamantane sulfonamide derivatives and tested their inhibitory activity against human and mouse 11b-HSD1. Compound 3 was identified as a lead compound with an IC50 of 0.6 nM against human 11b-HSD1 and 26 nM against mouse 11b-HSD1. Further modifications to the linker and substituents were made based on molecular modeling studies. Several substituted phenyl derivatives also showed potent inhibitory activity in the low nanomolar range. Compound 3 demonstrated good selectivity versus 11
1. Five hydroxamate small molecule inhibitors and three quinoline inhibitors were evaluated for their ability to inhibit Botulinum neurotoxin type A (BoNT-A) using an in vitro LC/MSMS assay. The hydroxamates exhibited high potency inhibition at 1 μM, while the quinolines showed much weaker inhibition and did not fully inhibit even at 400 μM.
2. A 66-mer peptide substrate containing the BoNT-A cleavage site was characterized and its N-terminal cleavage product was identified. Using this longer substrate requires less BoNT-A light chain protease for experiments, reducing costs.
3. Two cyclic peptides previously shown to inhibit BoNT-A were characterized in
1. Water lettuce is a floating plant found in ponds. Its buoyancy is assisted by water's high specific heat and latent heat of vaporization.
2. Sucrose is a disaccharide made of glucose and fructose that is efficiently transported in phloem tissue because it is very soluble and can move in high concentrations.
3. Fertilization in flowering plants occurs when a pollen nucleus fuses with the egg cell nucleus in the embryo sac of the ovule.
This document contains a series of questions about aromatic compounds and their reactions. It asks the reader to identify aromatic compounds, predict products of substitution and other reactions involving aromatic rings, draw reaction mechanisms, and propose syntheses of compounds through multiple step reactions starting from various reagents. It covers topics such as electrophilic aromatic substitution, nitration, sulfonation, Friedel-Crafts reactions, and the use of diazonium salts and other intermediates in multi-step syntheses.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against developing mental illness and improve symptoms for those who already suffer from conditions like anxiety and depression.
This document describes the design, synthesis, and evaluation of a series of 1,3-disubstituted pyrrolo[2,3-b]quinoxalines as potential inhibitors of phosphodiesterase 4 (PDE4) and cancer cell growth. A ligand- and phase transfer catalyst-free intramolecular Heck reaction was used to synthesize the target compounds. Some compounds showed significant inhibition of PDE4B and growth inhibition of oral cancer cells in vitro. They also showed acceptable safety profiles in zebrafish embryos, but no apoptosis was observed. The goal was to develop PDE4 inhibitors that do not inhibit luciferase, which could produce false positives in assays.
This summary provides the key details about the document in 3 sentences:
The document describes the synthesis of new triciribine analogues as potential anti-HCV agents. Ten new β-D-ribofuranosyl and 20-β-C-methyl-β-D-ribofuranosyl triciribine derivatives were synthesized with various N4 and 6-N substituents. Some of the new compounds showed interesting anti-HCV activity with low cytotoxicity based on inhibitory studies in the HCV replicon assay.
1. The document describes the design and synthesis of molecules that mimic the natural selectin ligand sialyl Lewis X (sLeX) to function as selectin antagonists.
2. Key modifications to the sLeX structure included replacing the GlcNAc saccharide unit with an acyclic tether, and installing benzoate groups at different positions on the galactose and fucose units.
3. The new molecules were evaluated for their ability to inhibit selectin interactions using assays with E-selectin and P-selectin. Compounds with benzoate groups at both C2 and C4 positions on galactose showed the highest potency as selectin antagonists.
1. A biochemical reaction network model is developed to explore APP-C99 homodimer formation and its binding to cholesterol, which are believed to play roles in Alzheimer's disease.
2. The model consists of kinetic equations that capture the association and dissociation of APP-C99 monomers, dimers, and APP-C99 bound to cholesterol.
3. The model is parameterized using experimental data and simulations of APP-C99 and cholesterol diffusion, and solved using particle-based and stochastic simulations.
Switching Off and On the Supramolecular Chiral Memory in PorphyrinAngela Mammana
This document summarizes research on switching the chiral memory in porphyrin assemblies on and off. The researchers designed a system using tetra-cationic and tetra-anionic porphyrins that form chiral supramolecular complexes when mixed in the presence of a chiral template, like an amino acid. This complex retains its chirality even after removing the template. The researchers found they could cycle the complex between "written" and "erased" states by turning the electrostatic interactions on and off via protonation/deprotonation. Protonation induces aggregation and chirality, while raising the pH leads to disassembly and loss of chirality, but chiral "seeds" allow reassembly of the
Two new classes of potent antimalarial compounds, 4-amidinoquinoline (4-AMQ) and 10-amidinobenzonaphthyridine (10-AMB) derivatives, were discovered that displayed high activity in vitro and in vivo against Plasmodium falciparum. The best analog, WR910397, showed nanomolar potency against three Pf clones, low inhibition of the hERG potassium channel, no mutagenicity, and cured 5 out of 5 mice infected with P. berghei at a dose of 15 mpk x 3. These results indicate that 4-AMQ and 10-AMB derivatives are promising candidates for developing new antimalarial drugs with potential advantages over
Synthesis and Catalytic Application of Chiral 1,1′-Bi-2-naphtholand Biphenant...DrMAdamSayah
Synthesis and Catalytic Application of Chiral 1,1′-Bi-2-naphtholand Biphenanthrol-Based Pincer Complexes- Selective Allylation of Sulfonimines with Allyl Stannane and Allyl Trifluoroborate
This study found that the yeast LEA-like protein HSP 12 is located on the plasma membrane. Immunogold labeling observed HSP 12 on the external side of the plasma membrane in stationary phase yeast. HSP 12 was found to protect liposomal membrane integrity during desiccation, acting similarly to trehalose. Protection was only observed with positively charged liposomes, indicating an electrostatic interaction between HSP 12 and membranes. Yeast lacking HSP 12 were less able to grow in ethanol-containing media, and HSP 12 conferred increased liposomal membrane integrity in the presence of ethanol.
This document contains 50 multiple choice questions related to biology, chemistry, and genetics. The questions cover a range of topics including enzyme kinetics, genetics, cellular processes, and metabolic pathways. For each question, four answer options are provided and only one answer is correct. All 50 questions must be answered.
tuning the pH Response of i-Motif DNA Oligonucleotides_Lannes_et_al-2015-Chem...saheli halder
This document discusses tuning the pH response of i-motif DNA oligonucleotides. The authors introduced 5-methylcytosines (5-MeC) and 5-bromocytosines (5-BrC) into the human telomeric i-motif sequence to shift its pH response range. They found that 5-MeC shifted the pH response towards more basic values, while 5-BrC shifted it towards more acidic values. Additionally, lengthening the sequence shifted the pH response in a more basic direction. The modifications did not thermally destabilize the i-motifs. 5-BrC substitution led to a ten-fold increase in folding kinetics compared to the other sequences.
1. The study examines how the substrate L-serine interacts with and stabilizes the active site of serine hydroxymethyltransferase (SHMT) enzymes from sheep liver and E. coli.
2. Results show L-serine enhances the thermal stability of both SHMT enzymes, increasing their apparent melting temperatures. Binding studies also indicate L-serine induces conformational changes in the enzymes without altering their overall structure.
3. The conformational changes upon L-serine binding, monitored by various spectroscopic methods, suggest L-serine compacts the enzyme structure, leading to increased thermal stability.
This document summarizes the discovery and optimization of novel phenylalanine diamide inhibitors of Factor XIa (FXIa). Exploration of substituents on the P1', P2', and P1 positions led to the identification of compound 21, which demonstrated high affinity for FXIa, good potency in clotting assays, selectivity over other serine proteases, and efficacy in a rabbit thrombosis model. X-ray crystallography provided insights into key interactions between optimized compounds and residues in the FXIa active site.
This study used NMR spectroscopy to measure hydrogen exchange rates of backbone amide protons in two disordered proteins, a-synuclein and FlgM, in buffer and inside Escherichia coli cells. The rates were similar in buffer and cells, and close to rates predicted from studies of unstructured peptides. This suggests that true disorder can persist inside the crowded cellular interior, and that weak interactions between proteins and macromolecules in cells do not necessarily affect intrinsic exchange rates. However, the C-terminal region of FlgM showed some evidence of transient structure formation in buffer that was not observed inside cells.
This document contains a series of questions about aromatic compounds and electrophilic aromatic substitution reactions. It asks the reader to identify aromatic compounds, predict products of various substitution reactions involving benzene and related aromatic rings, explain directing effects of different substituents, and draw resonance structures of arenium ions formed in electrophilic aromatic substitution. The questions cover topics such as naming compounds, determining substituent effects, predicting reaction mechanisms, and requiring multi-step synthesis of aromatic compounds.
Enzyme Discovery for Natural Product BiosynthesisHongnan Cao
A poster presentation of collaborative work on the NIH funded project of Enzyme Discovery for Natural Product Biosynthesis at 2015 American Crystallography Association Meeting at Philadelphia, PA. Thanks to Rice University, University of Wisconsin-Madison, The Scripps Research Institute, University of Kentucky, The Midwest Center for Structural Genomics, The Northeast Center for Structural Genomics, APS synchrotron at Argonne National Lab
This document describes research into developing a potent and selective inhibitor of 11b-hydroxysteroid dehydrogenase type 1 (11b-HSD1) for the treatment of type 2 diabetes. The researchers synthesized various adamantane sulfonamide derivatives and tested their inhibitory activity against human and mouse 11b-HSD1. Compound 3 was identified as a lead compound with an IC50 of 0.6 nM against human 11b-HSD1 and 26 nM against mouse 11b-HSD1. Further modifications to the linker and substituents were made based on molecular modeling studies. Several substituted phenyl derivatives also showed potent inhibitory activity in the low nanomolar range. Compound 3 demonstrated good selectivity versus 11
1. Five hydroxamate small molecule inhibitors and three quinoline inhibitors were evaluated for their ability to inhibit Botulinum neurotoxin type A (BoNT-A) using an in vitro LC/MSMS assay. The hydroxamates exhibited high potency inhibition at 1 μM, while the quinolines showed much weaker inhibition and did not fully inhibit even at 400 μM.
2. A 66-mer peptide substrate containing the BoNT-A cleavage site was characterized and its N-terminal cleavage product was identified. Using this longer substrate requires less BoNT-A light chain protease for experiments, reducing costs.
3. Two cyclic peptides previously shown to inhibit BoNT-A were characterized in
1. Water lettuce is a floating plant found in ponds. Its buoyancy is assisted by water's high specific heat and latent heat of vaporization.
2. Sucrose is a disaccharide made of glucose and fructose that is efficiently transported in phloem tissue because it is very soluble and can move in high concentrations.
3. Fertilization in flowering plants occurs when a pollen nucleus fuses with the egg cell nucleus in the embryo sac of the ovule.
This document contains a series of questions about aromatic compounds and their reactions. It asks the reader to identify aromatic compounds, predict products of substitution and other reactions involving aromatic rings, draw reaction mechanisms, and propose syntheses of compounds through multiple step reactions starting from various reagents. It covers topics such as electrophilic aromatic substitution, nitration, sulfonation, Friedel-Crafts reactions, and the use of diazonium salts and other intermediates in multi-step syntheses.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against developing mental illness and improve symptoms for those who already suffer from conditions like anxiety and depression.
Prevención de enfermedades en menores de 0 a 9 años.Paola Perales
Este documento describe varias acciones de salud preventivas y su frecuencia recomendada. Incluye aplicar gotas oftálmicas y vitamina K al nacer, realizar quimioprofilaxis para tuberculosis cada que haya contacto con pacientes, detectar placa dental cada seis meses a partir de los 3 años, e instruir técnicas de cepillado dental y uso de hilo dental de forma permanente a partir del primer y octavo año respectivamente. También recomienda aplicar flúor tópico cada seis meses a partir de los 3 años.
Lawrence, Kansas is considered a quirky city known for its vibrant downtown filled with local boutiques, restaurants, art, music, and festivals. It is home to two universities - the University of Kansas and Haskell Indian Nations University. Lawrence has a history dating back to the 1850s when it was founded as an anti-slavery settlement and was later burned during the Civil War. There is plenty to explore in Lawrence from its charming downtown to its arts scene and universities.
This document appears to contain contact information for a business called Hair Fashions 'n' Skin Care located in New Delhi, India. It lists phone numbers 7292092070 and 011-42880937 and an address of GG1/2C, Vikaspuri, New Delhi – 110018.
Chloroplasts are organelles found in plant cells where photosynthesis occurs, providing plants with energy. They contain chlorophyll which makes them green and are disc-shaped structures 2-10 micrometers wide. Plant cells contain 10-100 chloroplasts which work with mitochondria to produce energy for the cell through similar processes, while the smooth endoplasmic reticulum was voted as less important because its functions do not directly affect chloroplast functions.
Part four map.pptx' with you from one drive personalreghilda
Hilda Regalado's family history project details the origins and movements of her parents from Mexico to California. Both of her parents were born and raised in Romita, Guanajuato, Mexico, with her father moving to Santa Barbara, CA at age 22 and her mother moving to La Habra, CA at age 18. They met in La Habra and got married, after which her mother moved with her father to Santa Barbara, where Hilda was raised.
El documento describe el sistema Claw®-RTM para monitoreo de presión y temperatura en tiempo real utilizando un sensor de cuarzo de alta precisión, una bomba Jet Claw® Smart y un data logger. El sistema permite optimizar pruebas de producción y monitorear el comportamiento continuo del pozo de manera remota.
This presentation can give an high level Test automation practices.
Visit for video:
https://www.youtube.com/watch?v=XlhM5FmKcsc&list=PL5NmC6t0N8tHJoaaOAjM58bhu18zzbPI1
Two DNA nanomachines were engineered to simultaneously map pH gradients along two intersecting endocytic pathways within the same living cell. One nanomachine (IFu) was programmed to enter via the furin retrograde pathway and map pH in early endosomes, late endosomes, and the trans-Golgi network. The other (ITf) was conjugated to transferrin to enter via the transferrin receptor pathway and map pH in early endosomes and the recycling endosome. When delivered together to cells expressing an artificial furin receptor, both nanomachines independently localized to and reported pH changes in their targeted organelles. This demonstrates the successful simultaneous functioning of distinct DNA nanodevices for multiplexed sensing within a
Luxury beauty brands - Sustainability is good for businessEdwige Riou
This document discusses how embracing sustainability practices can benefit luxury beauty brands. It notes that consumers are increasingly concerned about environmental issues and expect brands to reflect their values. While some luxury brands have made progress in areas like sustainable packaging and recycling programs, the document argues they need to do more, such as improving sustainability practices for point-of-sale marketing materials which produce large amounts of waste. Focusing on accurate forecasting, reuse of displays, and partnerships with ethically focused suppliers can help luxury beauty brands better meet consumer demands while reducing environmental impacts and costs.
Análisis de de textos revisados en la construcción de la historia del arte de...cediel1952
Este documento presenta un resumen de 10 investigaciones relacionadas con la deontología docente. Los estudios analizados tienden a establecer normas sobre temas como la profesión docente, la relación con compañeros y estudiantes, y la responsabilidad social. Las estrategias incluyen análisis de principios éticos y comparativos aplicados a diferentes ámbitos de la enseñanza. El documento concluye que abordar la enseñanza de la ética y deontología docente requiere considerar su justificación, contenido y forma
1) Adamantyl-tethered-biphenylic compounds were synthesized and found to induce apoptosis in cancer cells.
2) Compound 30-(adamantan-1-yl)-40-methoxy-[1,10-biphenyl]-3-ol (AMB) showed cytotoxic activity against hepatocellular carcinoma cell lines without harming normal cells.
3) AMB was found to target and downregulate anti-apoptotic Bcl-2 family proteins like Bcl-2 and Bcl-xL, leading to cell cycle arrest and induction of apoptosis in cancer cells.
The document describes a facile synthesis of 4-(1H-benzo[d]imidazol-2-yl)-furazan-3-amines (BIFAs) via the condensation reaction of 4-aminofurazan-3-carbohydroximoyl chloride and substituted o-phenylenediamines. This synthesis proceeds under mild conditions in good yields without requiring purification of intermediates. The resulting BIFA derivatives were evaluated for their ability to destabilize microtubules in sea urchin embryos and inhibit proliferation of human cancer cell lines. Several BIFAs showed low micromolar anti-proliferative activity through both in vivo and in vitro assays. The most potent compound
NatPro was established in 2011 with NIH funding to determine enzyme structures from natural product biosynthetic pathways using PSI technologies. NatPro has determined over 60 enzyme structures from antitumor antibiotic pathways. These structures reveal active sites and enzymatic reactions, identify new natural products, and offer opportunities to customize pathways. The range of structures includes glycosyltransferases, methyltransferases, PKS domains, and enzymes with novel activities.
1) The document describes the design and synthesis of new (bis)ureidopropyl and (bis)thioureidopropyl diamine compounds as inhibitors of the histone demethylase LSD1.
2) Key compounds featured 3-5-3 and 3-6-3 carbon backbone architectures. Several compounds displayed single-digit micromolar IC50 values against recombinant LSD1 in vitro.
3) Compound 6d showed low micromolar cell viability IC50 values against lung and breast cancer cell lines. It also increased mRNA expression of silenced tumor suppressor genes in lung cancer cells.
Expression, purification and spectroscopic characterization of the cytochrome...John Clarkson
K.J. McLean, M.R. Cheesman, S.L. Rivers, A. Richmond, D. Leys, S.K. Chapman, G.A. Reid, N.C. Price, S.M. Kelly, J. Clarkson, W.E Smith & A.W. Munro, “Expression, Purification and Spectroscopic Characterization of the Cytochrome P450 CYP121 from Mycobacterium Tuberculosis”, J. Inorganic Biochemistry, 91, 527-541, 2002.
This document describes a study that synthesized a new class of tyrosinase inhibitors called azachalcones. Azachalcone derivatives were tested for their ability to inhibit the enzyme tyrosinase, which is involved in melanin biosynthesis. Two compounds that were reduction products of pyridinyl azachalcones strongly inhibited tyrosinase activity and were more potent inhibitors than the positive control kojic acid. Kinetic studies showed that these two compounds act as competitive inhibitors of tyrosinase by binding to the enzyme's active site. This new class of azachalcone inhibitors could potentially be used as depigmenting agents or to prevent browning in foods.
It is my journal club presentation on Synthesis, Docking Studies and Anticancer Activity of New Substituted Pyrimidine and Triazolopyrimidine Glycosides.
I sincerely thank the authors Wael A. El-Sayed, Ashraf M. Mohamed , Hemat S. Khalaf, Dina S. EL-Kady, May Al-Manawaty
Synthesis, characterization, amdet and docking studies of novel diclofenac de...Alexander Decker
This document discusses the synthesis and characterization of novel diclofenac derivatives containing phenylalanine moieties as selective inhibitors of cyclooxygenase-2 (COX-2). Sixteen novel diclofenac derivatives were synthesized and their structures were confirmed through various analytical techniques. Molecular docking studies predicted that compounds 7, 12 and 16 showed stronger binding with COX-2 than the reference drug diclofenac, making them potential selective COX-2 inhibitors. The binding scores of these compounds were higher than diclofenac when docked into the active site of COX-2.
This document reports on a ligand-free multi-component reaction for linking a quinoxaline framework to a benzimidazole nucleus to generate novel hybrid molecules as potential inducers of apoptosis. The reaction involves N-(prop-2-ynyl)quinoxalin-2-amine derivatives, 2-iodoanilines, and tosyl azide in the presence of copper iodide and triethylamine in DMSO. This produces the target hybrid molecules containing a quinoxaline-benzimidazole linkage in good yields within 30 minutes. Some of the synthesized compounds showed encouraging apoptosis inducing properties in zebrafish embryos.
Facile Syntheses of Substituted, Conformationally-Constrained Benzoxazocines ...JamesSahn
A multicomponent assembly process (MCAP) was utilized to prepare versatile intermediates that are suitably functionalized for subsequent cyclizations via Ullmann and Heck reactions to efficiently construct substituted 2,6-methanobenzo[b][1,5]oxazocines and 1,6-methanobenzo[c]azocines, respectively. The intramolecular Ullmann cyclization was conducted in tandem with an intermolecular arylation that enabled the rapid syntheses of a number of O-functionalized methanobenzoxazocines.
Source: Tetrahedron Lett. 2011 December 21; 52(51): 6855–6858.
1) Rv3717 is a novel N-acetylmuramoyl-L-alanine amidase enzyme from Mycobacterium tuberculosis that was determined to have a single-domain structure at 1.7 Angstrom resolution.
2) Unlike other bacterial autolysins, Rv3717 lacks a separate cell-wall binding domain and instead uses its net positive charge for substrate binding.
3) The crystal structure revealed a flexible hairpin turn that partially occludes the active site, which may be involved in autoregulation of enzymatic activity similar to other bacterial amidases.
This document describes the efficient synthesis of glaziovianin A (GVA) and related isoflavones starting from readily available plant metabolites. A six-step reaction sequence involving bromination, alkylation, oxidation, condensation, epoxidation, and cyclization produced GVA and various alkoxyphenyl derivatives. Both an in vivo sea urchin embryo assay and screening of human cancer cell lines showed that GVA and some derivatives have antimitotic effects by destabilizing microtubules. Structure-activity relationship studies found that certain substituents, such as a methylenedioxy or trimethoxy group, influenced the compounds' potency. GVA was generally the most active compound, inhibiting cancer cell
This document describes the synthesis and anticancer activity of novel 1,2,3-triazole derivatives tethered to a 1,2-benzisoxazole scaffold. Specifically:
- Compounds were synthesized via copper-catalyzed azide-alkyne cycloaddition between benzisoxazole-3-azide and various alkynes.
- The most potent compound, PTB, showed low micromolar anticancer activity against acute myeloid leukemia cell lines via apoptosis induction and cell cycle arrest.
- PTB was found to inhibit histone deacetylases, leading to increased acetylation of histone H3 and tubulin, as well as upregulation of p21
NMR spectroscopy techniques including 2D TOCSY, ROESY, and STD NMR were used to analyze peptide epitopes and determine their binding to monoclonal antibodies. 2D NMR was used to assign proton signals in peptide epitopes. STD NMR showed that the peptide GVTSAX3D binds to antibody SM3 through interactions of the 3-aminobenzoate substitution and methyl groups of valine, threonine, and alanine residues. Mass spectrometry and NMR spectroscopy supported the successful synthesis and characterization of peptide epitopes for studying antibody binding.
1. Chemical mutagens include alkylating agents, base analogues, intercalating agents, and deaminating agents. Alkylating agents can add alkyl groups to molecules and cause mutations by altering DNA bases.
2. Intercalating agents like proflavin insert between DNA base pairs, increasing rigidity and altering DNA confirmation which can cause frameshift mutations.
3. Base analogues like 5-bromouracil are structurally similar to normal bases but have slightly altered base-pairing properties, inducing nonsense or missense mutations.
This document describes a study investigating potential inhibitors of human calcium–calmodulin dependent protein kinase IV (CAMKIV) containing a pyrimidine scaffold. Through molecular docking and fluorescence binding studies, three pyrimidine-substituted compounds (molecules 1-3) were identified as having high binding affinity for CAMKIV. Molecule 3 showed the highest binding affinity with a binding constant of 2.2 × 108 M−1. The three compounds were nontoxic to cells and molecule 3 had the lowest IC50 value, indicating it inhibits cell proliferation the most. This study provides insights for developing improved pyrimidine-based compounds as potential therapeutic agents for cancer and neurodegenerative diseases by targeting CAMKIV
This document describes the design, synthesis, and evaluation of novel thrombin inhibitors incorporating P3-P4 lactam sulfonamide moieties. The inhibitors were designed to exploit interactions with thrombin's S2 and S3 sites to improve selectivity over related serine proteases. A series of 5-7 membered lactam rings were synthesized and incorporated a P1 argininal group. X-ray crystallography of one inhibitor bound to thrombin confirmed the predicted binding mode. In vitro testing showed several inhibitors had low nanomolar IC50 values against thrombin and good selectivity over trypsin and factor Xa. Overall, the lactam sulfonamides represent a new class of orally bioavailable
Bacteria Induced Cryptic Meroterpenoid Pathway in Pathogenic Aspergillus fumi...Debanjan Chatterjee
The document summarizes a presentation on inducing a cryptic meroterpenoid pathway in the pathogenic fungus Aspergillus fumigatus through co-cultivation with the actinomycete Streptomyces rapamycinicus. Co-cultivation led to the activation of a previously silent polyketide synthase gene cluster and the production of novel prenylated polyketides, including Fumicyclines A. Deletion of the polyketide synthase gene confirmed its involvement in biosynthesis. While co-cultivation induced pathway expression, inhibition of histone acetyltransferase did not, suggesting the bacterium alters fungal epigenetic regulation. Understanding secondary metabolism in A. f
The document describes the synthesis and evaluation of nitromethane substituted chalcone derivatives for their antimicrobial and antitubercular activity. Chalcones were synthesized from substituted acetophenones and aldehydes under basic conditions. Michael adducts were obtained by reacting the chalcones with nitromethane under Michael addition reaction conditions. The structures of the compounds were characterized using NMR and IR spectroscopy. Docking studies were performed to study the binding interactions of the compounds with various Mycobacterium tuberculosis protein targets. The compounds were evaluated for their in vitro antitubercular, anthelmintic and antimicrobial activity. Some compounds showed good activity against Mycobacterium tuberculosis and against various microorgan
This document describes research into synthesizing and evaluating Michael adducts derived from chalcones for biological activity. Michael adducts were synthesized by reacting chalcones with nitromethane under basic conditions. Various chalcones were first synthesized by reacting substituted acetophenones with substituted aldehydes under basic conditions. The resulting Michael adducts underwent molecular docking studies against various Mycobacterium tuberculosis protein targets as well as evaluation for anti-tubercular, anthelmintic, and antimicrobial activity. Several of the synthesized compounds showed promising anti-tubercular activity at 50μg/ml and good anthelmintic activity, suggesting electron donating groups aid activity.
Similar to 2014. Pietkiewicz, Wahyudi. Synthesis of macrocycles that inhibit protein synthesis SanB (20)
2014. Pietkiewicz, Wahyudi. Synthesis of macrocycles that inhibit protein synthesis SanB
1. Synthesis of macrocycles that inhibit protein synthesis:
stereochemistry and structural based studies on sanguinamide B
derivatives
Adrian L. Pietkiewicz, Hendra Wahyudi, Jeanette R. McConnell, Shelli R. McAlpine ⇑
School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
a r t i c l e i n f o
Article history:
Received 25 August 2014
Revised 8 October 2014
Accepted 14 October 2014
Available online 25 October 2014
Keywords:
Sanguinamide B
Macrocycle
Heterocycle
Natural product
Conformation
Peptide
a b s t r a c t
We report the synthesis of seven new sanguinamide B (SanB) analogues. Substitution of amino acids
along the backbone of SanB and testing in HCT-116 colon cancer cell lines identified new biologically
active SanB derivatives. These compounds establish a structure–activity relationship and show that a
Cbz-lysine moiety is important for biological activity. We also identified the most effective stereochem-
istry at each position around the molecule. The biological activity of the macrocycle is extremely sensitive
to stereochemistry and amino acid placement.
Ó 2014 Elsevier Ltd. All rights reserved.
Currently, over 50% of pharmaceutical compounds are derived
from natural product backbones, and as such they are excellent
lead structures in the development of new therapeutic com-
pounds.1–3
Over the past two decades, peptidic macrocycles
derived from natural products have been extensively studied for
their biological activity against cancer, HIV, hypertension and oste-
oporosis.4,5
Cyclic structures are extremely promising drug candi-
dates as they have fewer potential conformations, which lead to
higher binding affinity, and they are less susceptible to protease
degradation compared with linear peptides.6,7
The macrocyclic peptide sanguinamide B (SanB) (1), was iso-
lated by Molinski et al. from the nudibranch mollusc, Hexabranchus
sanguineaus (Fig. 1).8
SanB contains a tandem 2,4-oxazole-thiazole moiety and a trans,
trans di-prolyl configuration. The first total synthesis of this com-
pound resulted in three conformers around the proline residues
(trans,trans; trans,cis; and cis,cis) in prolines A and B, respectively.9
Biological testing showed all three conformers disrupted the
twitching activity of Pseudomonas aeruginosa,9
although none was
biologically active in cancer cell growth inhibition assays.10–12
structure–activity relationship (SAR) was investigated by synthe-
sizing the analogues using N-Me, glycine, L- and D-phenylalanine
(Phe) variations and evaluating them in cytotoxicity assays.10–12
Compounds 2 and 3 had the lowest IC50 values of 43 lM and
38 lM, respectively, against HCT116 colon cancer cell lines
(Fig. 1), indicating that incorporation of D-Phe results in cancer cell
growth inhibition.12
En route to undertaking a pull-down assay on
both compounds in order to identify their biological target, com-
pound 4 was generated, which contained a carboxybenzyl-lysine
(N6-Cbz-Lys) residue at position I (Fig. 1). Biological testing
revealed that this compound had an IC50 value of 15.9 lM, by far
the most potent analogue.12
Compounds 2, 3 and 4 were tested
in protein translation assays, and all three demonstrated inhibition
of protein synthesis, which was consistent with the proteins iden-
tified in the pull-down assays.12
Herein we describe additional structure–activity relationship
studies starting with the lead structure 4. Seven new analogues
(5–11) were generated by altering the amino acids at positions I
and III, inverting the stereochemistry at position III and altering
the Cbz residue on the lysine (Fig. 2). Structures of these seven
compounds were confirmed, including the proline cis and trans
conformations. Each isolated conformation was then tested for
cytotoxicity against colon cancer cell lines and for their ability to
inhibit protein synthesis.
Compounds 5 and 6 (Fig. 2) had the Cbz removed, with com-
pound 6 incorporating an acetyl protecting group on the lysine. It
was anticipated that the acetyl group would be cleaved upon cell
entry, thus allowing us to evaluate the impact of the free amine
in the cell. Compound 7 was designed to mimic 4, but with the
http://dx.doi.org/10.1016/j.tetlet.2014.10.089
0040-4039/Ó 2014 Elsevier Ltd. All rights reserved.
⇑ Corresponding author. Tel.: +61 4 1672 8896; fax: +61 2 9385 6111.
E-mail address: s.mcalpine@unsw.edu.au (S.R. McAlpine).
Tetrahedron Letters 55 (2014) 6979–6982
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
2. Cbz-Lys at position III instead of I, and as with SanB (1) maintained
the L-valine (Val) at position I. Compound 8 was based on the activ-
ity of 2 and 3, and had a D-Phe incorporated into positions II and III,
while maintaining the L-Val at I. Compound 9 maintained the
active moieties of 4, while including a D-Phe at position III. Com-
pounds 10 and 11 mimicked 4 but replaced the L-Leucine (Leu)
at III with an L-Phe or D-Leu, respectively.
The synthesis of each compound was achieved by convergent
peptide coupling of two fragments: Fragment A (12) and Fragment
B (13) (Scheme 1). Fragment A was synthesized via peptide
coupling of D-Phe thiazole 14 with the appropriate amino acid
15. Thiazole 14 was synthesized via a modified Hantzsch reaction
between D-Phe thioamide 16 and ethyl bromopyruvate (17). The
former was synthesized from Boc-D-phenylalanine. Fragment B
(13) was produced via peptide coupling between 18 and the
appropriate amino acid, and subsequent peptide coupling of this
intermediate with a proline ester. Intermediate 18 was formed
via a modified Hantzsch thiazole reaction between bromoketo-
oxazole 19 and Pro-thioamide 20. Bromoketo-oxazole 19 was
prepared via cyclization and oxidation of peptidyl serine (Ser)
21, which was synthesized via a coupling reaction between
methoxylated bromopyruvic acid 22 and benzyl-protected serine
ester-amine 23.
The synthesis of Fragment A used in the synthesis of analogues
5, 9, 10 and 11 (Scheme 2) began with the protection of the acid
NHBoc-D-Phe-OH using trimethylsilyl diazomethane (TMSD).
The resulting ester 24 was converted into the amide 25 using
ammonium hydroxide, followed by subsequent conversion into
the thioamide 16 using Lawesson’s reagent. Condensing 16 with
ethyl bromopyruvate in the presence of KHCO3 gave the thiazoline
intermediate, which was oxidized using trifluoroacetic anhydride
(TFAA) in the presence of pyridine and triethylamine yielding 14.
Deprotection utilizing trifluoroacetic acid (TFA) gave the free
amine 26 and subsequent coupling with N6-Cbz-L-Lys employing
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
SanB-6
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
H
N
O
O
SanB-9
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
H
N
O
O
SanB-11
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
SanB-5
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
SanB-7
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
O
H
N
O
O
SanB-10
H
N
O
CH3
H2N
H
N
O
O
SanB-8
O
N S
NO
N
O
HN
O
S
N
NH
O
NH
N
OHN
4 A-trans B-cis
O
O
A
B
I
II
III
Figure 2. Synthesized SanB analogues, based on the lead structure 4. Residues that
are boxed were modified compared to 4.
O
N
S
N
O
N
O
HN
O
S
NN
H
O
NH
N
O
R2R1
O
S
N
N
H
EtO
O
NHBoc
S
N
N
N
O
O
N
OMe
O
OBocHN
R2
Fragment A
Fragment B
R1
SanB analogue
12
13
OS
N
NHBoc
OEt
BocHN OH
O
S
NH2
NHBoc
Br OEt
O
O
Modified
Hantzsch
R1
14
16
15
17
S
N
BocN
N
O
O
OMe
S
NH2
NBoc
N
O
O
OMe Br
O
Peptide
coupling
Modified
Hantzsch
18
2019
O
OMe
NH
HO
O OMe
OMe
Br
Br OH
O
MeO OMe
O
OMe
NH2
BnO
Peptide
coupling Cyclization
Oxidation
21
22
23
Hydrogenation
Peptide
coupling
Peptide
coupling
Scheme 1. Retrosynthetic strategy for SanB analogues.
O
OH
NHBoc
TMSD,
benzene:MeOH
(3:1)
(0.1 M)
NH4OH:MeOH (1:1)
(0.025 M)
Lawesson'sreagent(0.7 equiv.)
benzene(0.05 M), 50 o
C
quant.
62%
1. KHCO3 (9 equiv.)
BrCH2C(O)CO2Et (1.2 equiv.)
DME (0.05 M)
2. pyridine (8 equiv.),
TFAA (4 equiv.),
DME (0.05 M), 0 o
C, 2h,
3. Et3N (2 equiv.), rt, 2 h
71% over 2 steps
O
S
N
OEt
Boc-CbzLys-OH (1.2 equiv,)
TBTU (0.8 equiv.)
HATU (0.8 equiv.)
DIPEA (12 equiv.)
CH2Cl2 (0.1 M)
NHBoc
anisole(2 equiv.)
TFA:CH2Cl2 (1:3)
(0.1 M)
O
S
N
OEt
HN O
HN NHBoc
quant.
quant. 91%
O
OMe
NHBoc
O
NH2
NHBoc
S
NH2
NHBoc
O
S
N
OEt
NH2
O O
24 25
16 14
26
12
Fragment A used in the
synthesis of compounds
5, 9, 10 and 11
Scheme 2. Synthesis of Fragment A, 12.
2 A-cis, B-cis
IC50: 43.0 µM
O
N S
NO
N
O
HN
OS
N
NH
O
NH
N
O
sanguinamide B
1 A-trans, B-trans
IC50: inactive
I
II III
A
B
O
N S
N
O
N
O
HN
OS
N
NH
O
NH
N
O
A
B
O
N S
NO
N
O
NH
OS
N
NH
O
NH
N
O
3 A-trans, B-cis
IC50: 38.0 µM
4 A-trans, B-cis
IC50: 15.9 µM
O
N S
NO
N
O
HN
OS
N
NH
O
NH
N
O
A
B
A
B
HN
O
O
Figure 1. SanB (1) and first generation analogues (describing their proline
orientation) with IC50 values against the HCT-116 colon cancer cell line.
6980 A. L. Pietkiewicz et al. / Tetrahedron Letters 55 (2014) 6979–6982
3. TBTU and HATU as coupling agents, yielded Fragment A (12). Frag-
ment A required for synthesizing derivatives 7 and 8 had an L-Val
incorporated in place of Lys, and derivative 6 replaced the N6-Cbz-
L-Lys with an N6-Ac-L-Lys.
The synthesis of Fragment B (Scheme 3), 13, was achieved by
reacting Boc-Ser(Bn)-OH (27) with TMSD to generate the ester,
which was subsequently converted into the amine 23. A coupling
reaction between bromo-ketal acid 22 and NH2-Ser(Bn)-OMe (23)
yielded bromomethoxyketal serine derivative 28, which was sub-
jected to hydrogenation yielding compound 21. Cyclization of 21
using dimethylaminosulfur trifluoride (DAST), followed by oxida-
tion with bromotrichloromethane (BrCCl3) and 1,8-diazabicy-
clo[5.4.0]undec-7-ene (DBU) generated the oxazole 29. Ketone
deprotection of 29 using formic acid gave 19, which was reacted
with Pro-thioamide derivative 20 under modified Hantzsch thia-
zole conditions to give the bisheterocycle 18. Amine deprotection
of 18 with trifluoroacetic acid (TFA) and elongation by peptide cou-
pling with NHBoc-amino acid gave the ester 30, where coupling of
L-Leu, D-Leu, L-Phe, D-Phe or N6-Cbz-L-Lys generated the corre-
sponding Fragment B analogues for each derivative. Coupling
between 30 and NH-Pro-OMe yielded 13.
Coupling between the free amine and free acid, after respective
amine and acid deprotection reactions, yielded linear precursor 31
(Scheme 4). Subsequent acid and amine deprotection of 31, fol-
lowed by macrocyclization under dilute conditions generated all
the analogues, except 5. Compound 5 was generated by synthesiz-
ing compound 4 and removing the Cbz group from the lysine using
HBr and acetic acid (33% HBr in acetic acid) at 0.1 M.
Each analogue was purified by HPLC and LCMS, and the result-
ing NMR spectra showed that numerous analogues had more than
one conformation (Table 1). Identification of each conformer uti-
lized 1
H and 13
C NMR and 2D NMR experiments (1
H–1
H COSY,
1
H–13
C HSQC, 1
H–13
C HMBC), as well as HPLC, LC/MS, and HRMS
(see Supporting information).
Utilizing a gradation of temperatures in a 1
H NMR analysis pro-
vided the optimal temperature at which sharp peaks were
observed in the NMR.10
Upon determining the optimal tempera-
ture for evaluation, 2D NMR data were collected at that tempera-
ture, which allowed identification of the configuration of each
prolyl amide bond present in the macrocycle. Examination of the
Pro Cb and Cc chemical shifts provides evidence of the Pro being
‘cis’ or ‘trans’. A Pro amide bond that adopts cis orientation has a
larger DdCbc than a Pro with an amide bond in the trans orienta-
tion.13
The Pro Cb and Cc shifts for each conformer are shown in
Table 1.
From the data, it appeared that neither proline has a preferred
conformation. Although individual proline shifts were visible in
the 2D NMR data, which allowed us to assign the proline orienta-
tion, all but one compound (compound 11) were inseparable mix-
tures. As observed by isolating each peak of the inseparable
mixture on the LCMS and re-injecting into the LCMS, these mole-
cules were in fact oscillating between the two conformations. For
example, 6A and 6B were isolated as an interconverting mixture
of cis, cis and trans, cis, where prolyl A was rapidly oscillating
between cis and trans. Compound 8 was also isolated as two inter-
converting conformations with Pro A also oscillating between cis
and trans. Compounds 9 and 11 had Pro B oscillating between cis
and trans, where compound 11 interconverted slowly enough that
the two conformations could be isolated (Table 1).
The results of the biological testing show that the Cbz-Lys group
is essential for activity, since removal or modification of this resi-
DMTMM (1 equiv.),
HATU (1 equiv.),
DIPEA (12 equiv.)
CH2Cl2 (0.1 M)
O
N
S
N
O
N
O
R2
OEt
OS
N
NH
O
NH
N
O
BocHN
anisole (2 equiv.)
TFA:CH2Cl2 (1:3)
(0.1 M)
LiOH.H2O (8 equiv.)
H2O2 (3.4 equiv.)
MeOH (0.1 M)
quant.
quant.
R1
Fragment B
13
O
N
S
N
O
N
O
R2
OEt
OS
N
NH
O
NHBoc
N
O
BocHN
R1
OMe
O
N S
NO
N
O
HN
OS
N
NH
O
NH
R1
N
O
1. LiOH.H2O (8 equiv.)
EtOH (0.1 M)
2. anisole (2 equiv.)
TFA:CH2Cl2 (1:3)
(0.1 M)
3. HATU (1 equiv.)
DMTMM (1 equiv.)
T3P (1 equiv.)
DIPEA (12 equiv.)
CH2Cl2 (0.0005 M)
10-79% over 3 steps
* for compound 5 HBr/AcOH (33%) 0.1 M
was added to 4 which removed the Cbz group
SanB analogue
31
Fragment A
12
Yields ranged from
33-98% over 3 steps
R2
R1 =
NH2
H
N CH3
O
NHCbz
R2 =
NHCbz
A
B
Scheme 4. Cyclization and synthesis of SanB analogues.
22 (1.2 equiv.)
TBTU (1 equiv.)
HATU (1 equiv.)
DIPEA (12 equiv.)
CH2Cl2 (0.1 M)
OMe
O
BnO
NH
O
OMe
Br
OMe
formic acid (0.1 M)
rt to 60 o
C
O
N
O
O
OMe Br
S
N
BocN
N
O
O
OMe
H2, Pd/C (10% w/w)
EtOH (0.1 M)
OMe
O
HO
NH
O
OMe
Br
OMe
1. DAST (2 equiv.)
K2CO3 (2 equiv.)
-78 o
C to rt
CH2Cl2 (0.1 M)
2. DBU (2 equiv.),
BrCCl3 (2 equiv.)
-46 o
C to rt
CH2Cl2 (0.1 M)
OMe
N
O
OMe Br
OMe
93%
OH
O
BnO
NH
Boc
1. TMSD
MeOH:benzene
(1:3)
(0.1 M)
2. anisole (2 equiv.)
TFA:CH2Cl2 (1:3)
(0.1 M)
OMe
O
BnO
NH2
O
1. KHCO3 (8 equiv.)
20 (1.2 equiv.)
DME (0.05 M)
2. pyridine (9 equiv.),
TFAA (4 equiv.),
DME (0.05 M)
0 o
C, 2 h,
3. Et3N (2 equiv.),
0 oC to rt, 2 h,
72% over 3 steps
quant. for 2 steps
83% quant.
75% over 2 steps
1. anisole (2 equiv.)
TFA:CH2Cl2 (1:3)
(0.1 M)
quant.
2. NHBoc-Amino Acid-OH (1.2
equiv.)
TBTU (1 equiv.)
HATU (1 equiv.)
DIPEA (12 equiv.)
CH2Cl2 (0.1 M)
84% over 2 steps
OMe
S
N
N
N
O
O
O
R2
BocHN
1. LiOH (8 equiv.)
MeOH (0.1 M)
N
S
N
N
N
O
O
O
R2
BocHN
O
OMe
2. NH-Pro-OMe (1.2 equiv.)
TBTU (1 equiv,)
HATU (1 equiv.)
DIPEA (12 equiv.)
CH2Cl2 (0.1 M)
74% over 2 steps
Fragment B
2327 28
21 29 19
18
30
13
Scheme 3. Synthesis of Fragment B, 13.
Table 1
Conformational assignment of SanB-14 (4) and its analogues 6–11. Orientation of the
prolyl amide bond is determined by DdCbc.13
(Data for SanB-4 were referenced from
the published result.12
Compound Conformer DdCbc13
Pro A DdCbc Pro B Assignment
SanB-412
5.7 9.5 trans, cis-
SanB-6 A 9.5 15.0 cis, cis
B 4.4 10.9 trans, cis
SanB-7 7.5 14.2 trans, cis
SanB-8 A 7.0 7.7 trans, trans
B 9.6 2.5 cis, trans
SanB-9 A 4.3 8.6 trans, cis
B 6.6 5.0 trans, trans
SanB-10 9.3 14.7 cis, cis
SanB-11 A 9.9 14.0 cis, cis
B 9.7 7.8 cis, trans
(see Supporting information for details on structure conformation.)
A. L. Pietkiewicz et al. / Tetrahedron Letters 55 (2014) 6979–6982 6981
4. due obliterates biological activity in the cytotoxicity and protein
synthesis assay (e.g., compounds 5, 6 and 8 in Table 2). Further-
more, biological activity is retained when the residue is incorpo-
rated at position III (e.g., compound 7). This highlights the
importance of not only the presence of a lysine group containing
a long hydrocarbon chain in the macrocycle, but also a bulky
hydrophobic phenyl group at the terminus. Due to the large num-
ber of freely rotatable bonds in the residue, it can adopt the desired
3D conformation to interact with its target whether it is located at
position I or III. Modification at position III is also tolerated when
substituting the L-Leu for L-Phe (e.g., compounds 7 and 10). Inter-
estingly, substitution of a D-Leu is tolerated but a D-Phe is not
(11 versus 9). It appears that the stereochemical orientation of
L-Phe resembles that of L-Leu, while the orientation of D-Phe suffi-
ciently detracts from this favoured 3D conformation resulting in an
inactive compound. While this change from D to L stereochemistry
at position III is significant with a bulky Phe residue, the same
position can tolerate either a D- or L-Leu residue, probably due to
the smaller nature of the residue having little impact on the ana-
logue binding to its protein target. Overall, SAR seems to dictate
L, D, L stereochemical configuration for positions I–III in order for
the analogue to have biological activity, though this does not
always hold true when smaller residues are incorporated at posi-
tion III. The conformation of each compound resulting from the
proline residues appears unrelated to its biological activity, as
there is no correlation to active compounds and their trans or cis
conformation around the prolyl bonds. As is precedented,14–19
biological activity is primarily related to the positioning (i.e.,
stereochemistry of the amino acid) and the structure of the
moieties placed around the macrocyclic backbone.
In conclusion, the original natural product SanB (1) had no cyto-
toxicity or ability to inhibit protein synthesis. Through an SAR
study, we were able to show that biologically active derivatives
must contain a lysine residue with a Cbz protecting group. The
interaction with the protein translation machinery is structure
specific, whereby in addition to a Cbz-Lys in position I or III, only
a single D-Phe is tolerated. Position III can tolerate D-Leu, L-Leu,
L-Phe but not D-Phe. We have generated three new compounds that
have IC50 cytotoxicity values in HCT-116 colon cancer cell lines of
622 lM, where these three compounds have the ability to inhibit
protein synthesis. Although only low micromolar inhibitors, our
work highlights a successful approach useful for building biological
activity into a macrocycle using amino acid side chains, stereo-
chemistry and proline conformations.
Acknowledgements
We thank the University of New South Wales for the UIPA to
H.W. and the TFS for J.R.M. Thank you also to the Mark Wainwright
Analytical Centre staff, especially Dr. Donald Thomas, for their
assistance. Finally, we thank the Australian National Health and
Medical Research Council (NHMRC) grant APP1043561.
Supplementary data
Supplementary data (Synthetic details, NMR spectra, LCMS and
HRMS data on all SanB analogues and intermediates used to gener-
ate the products. Biological protocols including IC50 curves and
luciferase assays are provided.) associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.tetlet.
2014.10.089.
References and notes
1. Kingston, D. G. I. J. Nat. Prod. 2010, 74, 496.
2. Lachance, H. J. Med. Chem. 2012, 55, 5989.
3. Cragg, G. M.; Newman, D. J. Biochim. Biophys. Acta 2013, 1830, 3670.
4. Marsault, E.; Peterson, M. L. J. Med. Chem. 1961, 2011, 54.
5. Loffet, A. J. Pept. Sci. 2002, 8, 1.
6. Veber, D. F.; Johnson, S. R.; Cheng, H.-Y.; Smith, B. R.; Ward, K. W.; Kopple, K. D.
J. Med. Chem. 2002, 45, 2615.
7. Driggers, E. M.; Hale, S. P.; Lee, J.; Terrett, N. K. Nat. Rev. Drug Discov. 2008, 7,
608.
8. Dalisay, D. S.; Rogers, E. W.; Edison, A. S.; Molinski, T. F. J. Nat. Prod. 2009, 72,
732.
9. Singh, E.; Ramsey, D. M.; McAlpine, S. R. Org. Lett. 2012, 14, 1198.
10. Wahyudi, H.; Tantisantisom, W.; Liu, X.; Ramsey, D. M.; Singh, E. K.; McAlpine,
S. R. J. Org. Chem. 2012, 77, 10596.
11. Wahyudi, H.; Tantisantisom, W.; McAlpine, S. R. Tetrahedron Lett. 2014, 55,
2389.
12. Tantisantisom, W.; Ramsey, D. M.; McAlpine, S. R. Org. Lett. 2013, 15, 4638.
13. Siemion, I. Z.; Wieland, T.; Pook, K.-H. Angew. Chem., Int. Ed. Engl. 1975, 14, 702.
14. Sellers, R. P.; Alexander, L. D.; Johnson, V. A.; Lin, C.-C.; Savage, J.; Corral, R.;
Moss, J.; Slugocki, T. S.; Singh, E. K.; Davis, M. R.; Ravula, S.; Spicer, J. E.; Oelrich,
J. L.; Thornquist, A.; Pan, C.-M.; McAlpine, S. R. Bioorg. Med. Chem. 2010, 18,
6822.
15. Pan, P. S.; Vasko, R. C.; Lapera, S. A.; Johnson, V. A.; Sellers, R. P.; Lin, C.-C.; Pan,
C.-M.; Davis, M. R.; Ardi, V. C.; McAlpine, S. R. Bioorg. Med. Chem. 2009, 17,
5806.
16. Singh, E. K.; Sellers, R. P.; Alexander, L. D.; McAlpine, S. R. Curr. Opin. Drug
Discov. Dev. 2008, 11, 544.
17. Otrubova, K.; Lushington, G. H.; Vander Velde, D.; McGuire, K. L.; McAlpine, S.
R. J. Med. Chem. 2008, 51, 530.
18. Rodriguez, R. A.; Pan, P.-S.; Pan, C.-M.; Ravula, S.; Lapera, S. A.; Singh, E. K.;
Styers, T. J.; Brown, J. D.; Cajica, J.; Parry, E.; Otrubova, K.; McAlpine, S. R. J. Med.
Chem. 1980, 2007, 72.
19. Otrubova, K.; McGuire, K. L.; McAlpine, S. R. J. Med. Chem. 1999, 2007, 50.
Table 2
Summary table depicting the compound number, IC50 activity against HCT-116 colon
cancer cells, and % protein synthesis inhibition in a biochemical luciferase translation
assay
Luciferase Translation Assay
D
M
SO
SanB
4
SanB
7SanB
10SanB
11ASanB
11BG
418
5uM
0
10
20
30
40
50
100
%LuciferaseInhibition
6982 A. L. Pietkiewicz et al. / Tetrahedron Letters 55 (2014) 6979–6982