Synthesis of the ?-Rhamnopyranosides and the 6-Deoxy-?-mannoheptopyranosides

A review is presented of the development of methods for the synthesis of ?-rhamnopyranosides and the related 6-deoxy-?-mannoheptopyranosides based on the 4,6-O-alkylidene directed synthesis of mannopyranosides and their 6-thia derivatives followed by selective reduction at the 6-position. Applications to total synthesis of complex bacterial oligosaccharides containing the title moieties are presented

A propos of glycosyl cations and the mechanism of chemical glycosylation

International audienc

Mechanisms of Stereodirecting Participation and Ester Migration from Near and Far in Glycosylation and Related Reactions

This review is the counterpart of a 2018 Chemical Reviews article (Adero, P. O.; Amarasekara, H.; Wen, P.; Bohe, L.; Crich, D. Chem. Rev. 2018, 118, 8242-8284) that examined the mechanisms of chemical glycosylation in the absence of stereodirecting participation. Attention is now turned to a critical review of the evidence in support of stereodirecting participation in glycosylation reactions by esters from either the vicinal or more remote positions. As participation by esters is often accompanied by ester migration, the mechanism(s) of migration are also reviewed. Esters are central to the entire review, which accordingly opens with an overview of their structure and their influence on the conformations of six-membered rings. Next the structure and relative energetics of dioxacarbeniun ions are covered with emphasis on the influence of ring size. The existing kinetic evidence for participation is then presented followed by an overview of the various intermediates either isolated or characterized spectroscopically. The evidence supporting participation from remote or distal positions is critically examined, and alternative hypotheses for the stereodirecting effect of such esters are presented. The mechanisms of ester migration are first examined from the perspective of glycosylation reactions and then more broadly in the context of partially acylated polyols.Peer reviewe

Importance of Co-operative Hydrogen Bonding in the Apramycin-Ribosomal Decoding A-Site Interaction

An intramolecular hydrogen bond between the protonated equatorial 7'-methylamino group of apramycin and the vicinal axial 6'-hydroxy group acidifies the 6'-hydroxy group leading to a strong hydrogen bond to A1408 in the ribosomal drug binding pocket in the decoding A site of the small ribosomal subunit. In 6'-epiapramycin, the trans-nature of the 6'-hydroxy group and the 7'-methylamino group results in a much weaker intramolecular hydrogen bond, and a consequently weaker cooperative hydrogen bonding network with A1408, resulting overall in reduced inhibition of protein synthesis and antibacterial activity

A novel class of 1H-MRI Contrast Agents based on the relaxation enhancement induced on water protons by 14N imidazole moieties

Acknowledgements: This project has received funding from the European Union Horizon 2020 research and innovation programme under grant agreement No 668119 (project “IDentIFY”) and from the ATTRACT project funded by the EC under Grant Agreement No.777222. This work was performed in the frame of the COST Action AC15209 (EURELAX). The Italian Ministry for Educationand Research (MIUR) is gratefully acknowledged for yearly FOE funding to the Euro-BioImaging Multi-Modal Molecular Imaging Italian Node (MMMI).Peer reviewedPostprin

In vivo assessment of tumour associated macrophages in murine melanoma obtained by low-field relaxometry in the presence of iron oxide particles

Acknowledgements The authors would like to acknowledge Dr Dana Dawson, University of Aberdeen, UK, for the supply of ferumoxytol. This project has received funding from the European Union Horizon 2020 research and innovation programme under grant agreement No 668119 (project “IDentIFY”) and it was performed in the frame of the COST Action AC15209 (EURELAX). Maria Rosaria Ruggiero was supported by a “FIRC-AIRC fellowship for Italy”. The Italian Ministry for Education and Research (MIUR) is gratefully acknowledged for yearly FOE funding to the Euro-BioImaging Multi-Modal Molecular Imaging Italian Node (MMMI). Data availability All data analysed during this study are included in this published article (and its supplementary information file). Other raw data required to reproduce these findings are available from the corresponding author on reasonable request.Peer reviewedPublisher PD

Monitoring tissue implants by field-cycling H-1-MRI via the detection of changes in the N-14-quadrupolar-peak from imidazole moieties incorporated in a "smart" scaffold material

Acknowledgements This work was performed in the frame of the COST Action AC15209 (EURELAX). The authors acknowledge the Italian Ministry of Research for FOE contribution to the EuroBioImaging MultiModal Molecular Imaging Italian Node (www.mmmi.unito.it). This project has received funding from the European Union Horizon 2020 research and innovation program under grant agreement No 668119 (project “IDentIFY”) and from the ATTRACT project funded by the EC under Grant Agreement No. 777222.Peer reviewedPostprin

Low-Field NMR Relaxometry for Intraoperative Tumour Margin Assessment in Breast-conserving Surgery

Funding: This project has received funding from the European Union Horizon 2020 research and innovation programme under grant agreement no. 668119 (project “IDentIFY”) and from AIRC under IG 2019, ID 23267 project (PI Geninatti Crich Simonetta). The authors acknowledge the Italian Ministry of Research for FOE contribution to the Euro-BioImaging MultiModal Molecular Imaging Italian Node (www.mmmi.unito.it accessed on 1 October 2020). Maria Rosaria Ruggiero was supported by a “FIRC-AIRC fellowship for Italy”. Acknowledgments: This work was performed in the frame of the COST Action CA15209 (EURELAX).Peer reviewedPublisher PD

Overview on Multienzymatic Cascades for the Production of Non-canonical α-Amino Acids

SM-R thanks the University of Granada for the support provided by project PPJI2017-1 and the European Cooperation in Science and Technology (COST Action CA15133). Authors are also grateful to the Andalusian Regional Government through Endocrinology & Metabolism Group (CTS-202).The 22 genetically encoded amino acids (AAs) present in proteins (the 20 standard AAs together with selenocysteine and pyrrolysine), are commonly referred as proteinogenic AAs in the literature due to their appearance in ribosome-synthetized polypeptides. Beyond the borders of this key set of compounds, the rest of AAs are generally named imprecisely as non-proteinogenic AAs, even when they can also appear in polypeptide chains as a result of post-transductional machinery. Besides their importance as metabolites in life, many of D-α- and L-α-“non-canonical” amino acids (NcAAs) are of interest in the biotechnological and biomedical fields. They have found numerous applications in the discovery of new medicines and antibiotics, drug synthesis, cosmetic, and nutritional compounds, or in the improvement of protein and peptide pharmaceuticals. In addition to the numerous studies dealing with the asymmetric synthesis of NcAAs, many different enzymatic pathways have been reported in the literature allowing for the biosynthesis of NcAAs. Due to the huge heterogeneity of this group of molecules, this review is devoted to provide an overview on different established multienzymatic cascades for the production of non-canonical D-α- and L-α-AAs, supplying neophyte and experienced professionals in this field with different illustrative examples in the literature. Whereas the discovery of new or newly designed enzymes is of great interest, dusting off previous enzymatic methodologies by a “back and to the future” strategy might accelerate the implementation of new or improved multienzymatic cascades.University of Granada PPJI2017-1European Cooperation in Science and Technology (COST) CA15133Andalusian Regional Government through Endocrinology & Metabolism Group CTS-20