FiveC-glycosyl functionalized lysine building blocks, featuringC-glycosidic derivatives of alpha-rhamnose, alpha-mannose, alpha-galactose, beta-galactose, and beta-N-acetyl glucosamine have been... Show moreFiveC-glycosyl functionalized lysine building blocks, featuringC-glycosidic derivatives of alpha-rhamnose, alpha-mannose, alpha-galactose, beta-galactose, and beta-N-acetyl glucosamine have been designed and synthesized. These derivatives, equipped with acid-labile protecting groups, are eminently suitable for solid-phase synthesis of multivalent glycopeptides. The lysine building blocks were prepared fromC-allyl glycosides that underwent a Grubbs cross-metathesis with an acrylate, followed by a reduction of the C=C double bond in the resulting alpha,beta-unsaturated esters, and liberation of the carboxylate to allow condensation with a lysine side chain. The thus obtainedC-glycosides, five in total, were applied in the solid-phase peptide synthesis (SPPS) of three glycopeptides, showing the potential of the described building blocks in the assembly of well-defined mimics of homo- and heteromultivalent glycopeptides and glycoclusters. Show less
Purpose Aberrantly expressed glycans in cancer are of particular interest for tumor targeting. This proof-of-conceptin vivostudy aims to validate the use of aberrant Lewis glycans as target for... Show morePurpose Aberrantly expressed glycans in cancer are of particular interest for tumor targeting. This proof-of-conceptin vivostudy aims to validate the use of aberrant Lewis glycans as target for antibody-based, real-time imaging of gastrointestinal cancers. Procedures Immunohistochemical (IHC) staining with monoclonal antibody FG88.2, targeting Lewis(a/c/x), was performed on gastrointestinal tumors and their healthy counterparts. Then, FG88.2 and its chimeric human/mouse variant CH88.2 were conjugated with near-infrared fluorescent (NIRF) IRDye 800CW for real-time imaging. Specific binding was evaluatedin vitroon human gastrointestinal cancer cell lines with cell-based plate assays, flow cytometry, and immune-fluorescence microscopy. Subsequently, mice bearing human colon and pancreatic subcutaneous tumors were imagedin vivoafter intravenous administration of 1 nmol (150 mu g) CH88.2-800CW with the clinical Artemis NIRF imaging system using the Pearl Trilogy small animal imager as reference. One week post-injection of the tracer, tumors and organs were resected and tracer uptake was analyzedex vivo. Results IHC analysis showed strong FG88.2 staining on colonic, gastric, and pancreatic tumors, while staining on their normal tissue counterparts was limited. Next, human cancer cell lines HT-29 (colon) and BxPC-3 and PANC-1 (both pancreatic) were identified as respectively high, moderate, and low Lewis(a/c/x)-expressing. Using the clinical NIRF camera system for tumor-bearing mice, a mean tumor-to-background ratio (TBR) of 2.2 +/- 0.3 (Pearl: 3.1 +/- 0.8) was observed in the HT-29 tumors and a TBR of 1.8 +/- 0.3 (Pearl: 1.9 +/- 0.5) was achieved in the moderate expression BxPC-3 model. In both models, tumors could be adequately localized and delineated by NIRF for up to 1 week.Ex vivoanalysis confirmed full tumor penetration of the tracer and low fluorescence signals in other organs. Conclusions Using a novel chimeric Lewis(a/c/x)-targeting tracer in combination with a clinical NIRF imager, we demonstrate the potential of targeting Lewis glycans for fluorescence-guided surgery of gastrointestinal tumors. Show less
Beenakker, T.J.M.; Wander, D.P.A.; Codée, J.D.C.; Aerts, J.M.F.G.; Marel, G.A. van der; Overkleeft, H.S. 2017
Cyclophellitol and cyclophellitol aziridine are potent and irreversible inhibitors of retaining β‐glucosidases. They preferentially adopt a 4H3 half‐chair conformation, thereby mimicking the... Show moreCyclophellitol and cyclophellitol aziridine are potent and irreversible inhibitors of retaining β‐glucosidases. They preferentially adopt a 4H3 half‐chair conformation, thereby mimicking the substrate‐transition‐state conformation characteristic of retaining β‐glucosidases. As a consequence, both compounds bind tightly to the enzyme active site, and attack of the catalytic nucleophile onto the epoxide/aziridine results in enzyme deactivation. Replacement of the epoxide oxygen in cyclophellitol by a (substituted) carbon yielded carba‐cyclophellitols, a conceptually new class of inhibitors of retaining β‐glucosidases, as we demonstrated in a recent communication. In this paper, in‐depth synthetic studies of this class of compounds are described, and the preparation of a comprehensive set of structurally and configurationally new carba‐cyclophellitols is presented. Show less
Volbeda, A.G.; Reintjens, N.R.M.; Overkleeft, H.S.; Marel, G.A. van der; Codée, J.D.C. 2016
