A single acyloxy group at C-2 can control the outcome of nucleophilic substitution reactions of pyran-derived acetals, but the extent of the neighboring-group participation depends on a number of... Show moreA single acyloxy group at C-2 can control the outcome of nucleophilic substitution reactions of pyran-derived acetals, but the extent of the neighboring-group participation depends on a number of factors. We show here that neighboring-group participation does not necessarily control the stereochemical outcome of acetal substitution reactions with weak nucleophiles. The 1,2-trans selectivity increased with increasing reactivity of the incoming nucleophile. This trend suggests the intermediacy of both cis-fused dioxolenium ions and oxocarbenium ions in the stereochemistry-determining step. In addition, as the electron-donating ability of the neighboring group decreased, the preference for the 1,2-trans products increased. Computational studies show how the barriers for the ring-opening reaction on the dioxolenium ions and the transition states to provide the oxocarbenium ions change with the electron-donating capacity of the C-2-acyloxy group and the reactivity of the nucleophile.Neighboring-group participation by C-2 acyloxy groups can control the 1,2-trans stereoselectivity of acetal substitution reactions with the employment of strong nucleophiles. 1,2-Trans selectivity increases with decreased electron-donating ability of the acyloxy groups at C-2.image. Show less
Vrande, K.N.A. van de; Filippov, D.V.; Codee, J.D.C. 2023
To probe the reaction mechanism, underlying the rearrangementofoft-used trichloroacetimidate glycosyl donors into the correspondinganomeric trichloroacetamides, we have used a combination of C-13-... Show moreTo probe the reaction mechanism, underlying the rearrangementofoft-used trichloroacetimidate glycosyl donors into the correspondinganomeric trichloroacetamides, we have used a combination of C-13- and N-15-labeled glycosyl trichloroacetimidate donorsin a series of crossover experiments. These unambiguously show thattrichloroacetamides are formed via an intermolecular aglycon transfermechanism. This insight enables the design of more effective glycosylationprotocols, preventing the formation of dead-end side products. Show less
Gelder, M.A.; Zanden, S.Y. van der; Vriends, M.B.L.; Wagensveld, R.A.; Marel, G.A. van der; Codee, J.D.C.; ... ; Neefjes, J.J.C. 2023
The anthracycline anti-cancer drugs are intensely usedin the clinicto treat a wide variety of cancers. They generate DNA double strandbreaks, but recently the induction of chromatin damage was... Show moreThe anthracycline anti-cancer drugs are intensely usedin the clinicto treat a wide variety of cancers. They generate DNA double strandbreaks, but recently the induction of chromatin damage was introducedas another major determinant of anti-cancer activity. The combinationof these two events results in their reported side effects. Whileour knowledge on the structure-activity relationship of anthracyclineshas improved, many structural variations remain poorly explored. Therefore,we here report on the preparation of a diverse set of anthracyclineswith variations within the sugar moiety, amine alkylation pattern,saccharide chain and aglycone. We assessed the cytotoxicity in vitro in relevant human cancer cell lines, and the capacityto induce DNA- and chromatin damage. This coherent set of data allowedus to deduce a few guidelines on anthracycline design, as well asdiscover novel, highly potent anthracyclines that may be better toleratedby patients. Show less
Gelder, M.A. van; Zanden, S.Y. van der; Vriends, M.B.L.; Wagensveld, R.A.; Marel, G.A. van der; Codee, J.D.C.; ... ; Neefjes, J.J.C. 2023
The anthracycline anti-cancer drugs are intensely used in the clinic to treat a wide variety of cancers. They generate DNA double strand breaks, but recently the induction of chromatin damage was... Show moreThe anthracycline anti-cancer drugs are intensely used in the clinic to treat a wide variety of cancers. They generate DNA double strand breaks, but recently the induction of chromatin damage was introduced as another major determinant of anti-cancer activity. The combination of these two events results in their reported side effects. While our knowledge on the structure–activity relationship of anthracyclines has improved, many structural variations remain poorly explored. Therefore, we here report on the preparation of a diverse set of anthracyclines with variations within the sugar moiety, amine alkylation pattern, saccharide chain and aglycone. We assessed the cytotoxicity in vitro in relevant human cancer cell lines, and the capacity to induce DNA- and chromatin damage. This coherent set of data allowed us to deduce a few guidelines on anthracycline design, as well as discover novel, highly potent anthracyclines that may be better tolerated by patients. Show less
Minnee, H.; Chung, H.W.; Rack, J.G.M.; Marel, G.A. van der; Overkleeft, H.S.; Codee, J.D.C.; ... ; Filippov, D.V. 2023
Adenosine diphosphateribosylation (ADP-ribosylation) is a crucialpost-translational modification involved in important regulatory mechanismsof numerous cellular pathways including histone... Show moreAdenosine diphosphateribosylation (ADP-ribosylation) is a crucialpost-translational modification involved in important regulatory mechanismsof numerous cellular pathways including histone maintenance and DNAdamage repair. To study this modification, well-defined ADP-ribosylatedpeptides, proteins, and close analogues thereof have been invaluabletools. Recently, proteomics studies have revealed histidine residuesto be ADP-ribosylated. We describe here the synthesis of a completeset of triazole-isosteres of ADP-ribosylated histidine to serve asprobes for ADP-ribosylating biomachinery. By exploiting Cu(I)- andRu(II)-catalyzed click chemistry between a propargylglycine buildingblock and an & alpha;- or & beta;-configured azidoribose, we have successfullyassembled the & alpha;- and & beta;-configured 1,4- and 1,5-triazoles,mimicking N(& tau;)- and N(& pi;)-ADP-ribosylated histidine, respectively.The ribosylated building blocks could be incorporated into a peptidesequence using standard solid-phase peptide synthesis and transformedon resin into the ADP-ribosylated fragments to provide a total offour ADP-ribosyl triazole conjugates, which were evaluated for theirchemical and enzymatic stability. The 1,5-triazole analogues mimickingthe N(& pi;)-substituted histidines proved susceptible to base-inducedepimerization and the ADP-ribosyl & alpha;-1,5-triazole linkage couldbe cleaved by the (ADP-ribosyl)hydrolase ARH3. Show less
Ishizuka, S.; Dijk, J.H.M. van; Kawakita, T.; Miyamoto, Y.; Maeda, Y.; Goto, M.; ... ; Yamasaki, S. 2023
Although leprosy(Hansen's disease) is one ofthe oldestknown diseases, the pathogenicity of Mycobacterium leprae (M. leprae) remains enigmatic. Indeed, the cellwall components responsible for the... Show moreAlthough leprosy(Hansen's disease) is one ofthe oldestknown diseases, the pathogenicity of Mycobacterium leprae (M. leprae) remains enigmatic. Indeed, the cellwall components responsible for the immune response against M. leprae are as yet largely unidentified. We reveal herephenolic glycolipid-III (PGL-III) as an M. leprae-specific ligand for the immune receptor Mincle. PGL-III is a scarcelypresent trisaccharide intermediate in the biosynthetic pathway toPGL-I, an abundant and characteristic M. leprae glycolipid.Using activity-based purification, we identified PGL-III as a Mincleligand that is more potent than the well-known M. tuberculosis trehalose dimycolate. The cocrystal structure of Mincle and a syntheticPGL-III analogue revealed a unique recognition mode, implying thatit can engage multiple Mincle molecules. In Mincle-deficient miceinfected with M. leprae, increased bacterial burdenwith gross pathologies were observed. These results show that PGL-IIIis a noncanonical ligand recognized by Mincle, triggering protectiveimmunity.PGL-III, a potent immunostimulatory glycolipid,is limitedin M. leprae by the quick addition of a single methylgroup to convert it into immunosuppressive PGL-I, which confers immuneescape. Show less
Madern, J.M.; Voorneveld, J.; Rack, J.G.M.; Kistemaker, H.A.V.; Ahel, I.; Marel, G.A. van der; ... ; Filippov, D.V. 2023
Adenosine diphosphate (ADP) ribosylation is an importantpost-translationalmodification (PTM) that plays a role in a wide variety of cellularprocesses. To study the enzymes responsible for the... Show moreAdenosine diphosphate (ADP) ribosylation is an importantpost-translationalmodification (PTM) that plays a role in a wide variety of cellularprocesses. To study the enzymes responsible for the establishment,recognition, and removal of this PTM, stable analogues are invaluabletools. We describe the design and synthesis of a 4-thioribosyl APRrpeptide that has been assembled by solid phase synthesis. The key4-thioribosyl serine building block was obtained in a stereoselectiveglycosylation reaction using an alkynylbenzoate 4-thioribosyl donor. Show less
Wang, Z.; Poveda, A.; Zhang, Q.; Unione, L.; Overkleeft, H.S.; Marel, G.A. van der; ... ; Codee, J.D.C. 2023
Zwitterionic polysaccharides (ZPSs) are exceptional carbohydrates,carrying both positively charged amine groups and negatively chargedcarboxylates, that can be loaded onto MHC-II molecules to... Show moreZwitterionic polysaccharides (ZPSs) are exceptional carbohydrates,carrying both positively charged amine groups and negatively chargedcarboxylates, that can be loaded onto MHC-II molecules to activateT cells. It remains enigmatic, however, how these polysaccharidesbind to these receptors, and to understand the structural featuresresponsible for this "peptide-like" behavior, well-definedZPS fragments are required in sufficient quantity and quality. Wehere present the first total synthesis of Bacteroidesfragilis PS A1 fragments encompassing up to 12 monosaccharides,representing three repeating units. Key to our successful syntheseshas been the incorporation of a C-3,C-6-silylidene-bridged "ring-inverted"galactosamine building block that was designed to act as an apt nucleophileas well as a stereoselective glycosyl donor. Our stereoselective synthesisroute is further characterized by a unique protecting group strategy,built on base-labile protecting groups, which has allowed the incorporationof an orthogonal alkyne functionalization handle. Detailed structuralstudies have revealed that the assembled oligosaccharides take upa bent structure, which translates into a left-handed helix for largerPS A1 polysaccharides, presenting the key positively charged aminogroups to the outside of the helix. The availability of the fragmentsand the insight into their secondary structure will enable detailedinteraction studies with binding proteins to unravel the mode of actionof these unique oligosaccharides at the atomic level. Show less
During chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role.... Show moreDuring chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role. Schistosoma mansoni soluble egg antigens (SEA) are bound and internalized by B cells and induce both human and mouse IL-10 producing Breg cells. To identify Breg-inducing proteins in SEA, we fractionated SEA by size exclusion chromatography and found 6 fractions able to induce IL-10 production by B cells (out of 18) in the high, medium and low molecular weight (MW) range. The high MW fractions were rich in heavily glycosylated molecules, including multi-fucosylated proteins. Using SEA glycoproteins purified by affinity chromatography and synthetic glycans coupled to gold nanoparticles, we investigated the role of these glycan structures in inducing IL-10 production by B cells. Then, we performed proteomics analysis on active low MW fractions and identified a number of proteins with putative immunomodulatory properties, notably thioredoxin (SmTrx1) and the fatty acid binding protein Sm14. Subsequent splenic murine B cell stimulations and hock immunizations with recombinant SmTrx1 and Sm14 showed their ability to dose-dependently induce IL-10 production by B cells both in vitro and in vivo. Identification of unique Breg cells-inducing molecules may pave the way to innovative therapeutic strategies for inflammatory and auto-immune diseases.Author summaryWorm parasites, such as schistosomes, are master regulators of the human immune system, manipulating the host response in order to prolong their survival in their host. As a bystander effect, they also reduce immune responses to allergens and/or auto antigens, thus protecting their host against inflammatory and auto-immune diseases. One of the immune cells involved in immune regulation is the IL-10-producing regulatory B (Breg) cells. Schistosome eggs release various molecules that induce the development of Breg cells, but the identity of these molecules is not yet fully known. In this study, the authors aimed to identify some of these molecules. They investigated both the involvement of glycans on high molecular weight schistosomal egg molecules, as well as dissected the role of proteins with a lower molecular weight coming from schistosomal eggs. Using proteomics, they targeted various interesting molecules, which they recombinantly expressed and confirmed the IL-10 inducing capacity in B cells in vitro and in vivo for 2 molecules. This new knowledge may explain the hyporesponsiveness found in chronic schistosome-infected people and may pave the way to new innovative therapies for inflammatory and auto-immune diseases. Show less
Herein, we describe a novel methodology for the regio-and stereoselectiveconvergent synthesis of 2-amino-2-deoxy-dithioglycosides via one-potrelay glycosylation of 3-O-acetyl-2-nitroglucal donors... Show moreHerein, we describe a novel methodology for the regio-and stereoselectiveconvergent synthesis of 2-amino-2-deoxy-dithioglycosides via one-potrelay glycosylation of 3-O-acetyl-2-nitroglucal donors.This unique organo-catalysis relay glycosylation features excellentsite- and stereoselectivity, good to excellent yields, mild reactionconditions, and broad substrate scope. 2-Amino-2-deoxy-glucosides/mannosidesbearing 1,3-dithio-linkages were efficiently obtained from 3-O-acetyl-2-nitroglucal donors in both stepwise and one-potglycosylation protocols. The dithiolated O-antigen of E. coli serogroup 64 was successfully synthesizedusing this newly developed method. Show less
Pitirollo, O.; Di Benedetto, R.; Henriques, P.; Gasperini, G.; Mancini, F.; Carducci, M.; ... ; Micoli, F. 2023
Group A Carbohydrate (GAC), conjugated to an appropriate carrier protein, has been proposed as an attractive vaccine candidate against Group A Streptococcus infections. Native GAC consists of a... Show moreGroup A Carbohydrate (GAC), conjugated to an appropriate carrier protein, has been proposed as an attractive vaccine candidate against Group A Streptococcus infections. Native GAC consists of a polyrhamnose (polyRha) backbone with N-acetylglucosamine (GlcNAc) at every second rhamnose residue. Both native GAC and the polyRha backbone have been proposed as vaccine components. Here, chemical synthesis and glycoengineering were used to generate a panel of different length GAC and polyrhamnose fragments. Biochemical analyses were performed confirming that the epitope motif of GAC is composed of GlcNAc in the context of the polyrhamnose backbone. Conjugates from GAC isolated and purified from a bacterial strain and polyRha genetically expressed in E. coli and with similar molecular size to GAC were compared in different animal models. The GAC conjugate elicited higher anti-GAC IgG levels with stronger binding capacity to Group A Streptococcus strains than the polyRha one, both in mice and in rabbits. This work contributes to the development of a vaccine against Group A Streptococcus suggesting GAC as preferable saccharide antigen to include in the vaccine. Show less
