Mechanism-based inhibitors and probes for neuraminidases

Neuraminidases are enzymes that cleave glycosidic linkages of sialic acid. These enzymes are involved in influenza infections as well as in many cellular processes in mammals and micro-organisms. Development of molecules that irreversibly inhibit these enzymes, as well as molecules that can covalently bind and also label these enzymes, is described in this thesis. These newly developed molecular tools can be used to study neuraminidsases. Better understanding of these enzymes could for example contribute to the timely invervention if new influenza strains emerge.Bio-organic Synthesi

Re-exploring the anthracycline chemical space for better anti-cancer compounds

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 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.Bio-organic Synthesi

Synthetic (N,N-dimethyl)doxorubicin glycosyl diastereomers to dissect modes of action of anthracycline anticancer drugs

Anthracyclines are effective drugs in the treatment of various cancers, but their use comes with severe side effects. The archetypal anthracycline drug, doxorubicin, displays two molecular modes of action: DNA double-strand break formation (through topoisomerase II alpha poisoning) and chromatin damage (via eviction of histones). These biological activities can be modulated and toxic side effects can be reduced by separating these two modes of action through alteration of the aminoglycoside moiety of doxorubicin. We herein report on the design, synthesis, and evaluation of a coherent set of configurational doxorubicin analogues featuring all possible stereoisomers of the 1,2-amino-alcohol characteristic for the doxorubicin 3-amino-2,3-dideoxyfucoside, each in nonsubstituted and N,N-dimethylated forms. The set of doxorubicin analogues was synthesized using appropriately protected 2,3,6-dideoxy-3-amino glycosyl donors, equipped with an alkynylbenzoate anomeric leaving group, and the doxorubicin aglycon acceptor. The majority of these glycosylations proceeded in a highly stereoselective manner to provide the desired axial alpha-linkage. We show that both stereochemistry of the 3-amine carbon and N-substitution state are critical for anthracycline cytotoxicity and generally improve cellular uptake. N,N-Dimethylepirubicin is identified as the most potent anthracycline that does not induce DNA damage while remaining cytotoxic.Chemical Immunolog

Synthetic (N,N-dimethyl)doxorubicin glycosyl diastereomers to dissect modes of action of anthracycline anticancer drugs

Bio-organic Synthesi