3-N,N-Dimethylamino-3-deoxy lincomycin: A structure-based hybrid between lincomycin and the desosamine unit of erythromycin

Salinomycin Hydroxamic Acids: Synthesis, Structure, and Biological Activity of Polyether Ionophore Hybrids

The polyether ionophore salinomycin has recently gained attention due to its exceptional ability to selectively reduce the proportion of cancer stem cells within a number of cancer cell lines. Efficient single step strategies for the preparation of hydroxamic acid hybrids of this compound varying in N- and O-alkylation are presented. The parent hydroxamic acid, salinomycin-NHOH, forms both inclusion complexes and well-defined electroneutral complexes with potassium and sodium cations via 1,3-coordination by the hydroxamic acid moiety to the metal ion. A crystal structure of an cationic sodium complex with a noncoordinating anion corroborates this finding and, moreover, reveals a novel type of hydrogen bond network that stabilizes the head-to-tail conformation that encapsulates the cation analogously to the native structure. The hydroxamic acid derivatives display down to single digit micromolar activity against cancer cells but unlike salinomycin selective reduction of ALDH(+) cells, a phenotype associated with cancer stem cells was not observed. Mechanistic implications are discussed.

Sweet antibiotics - the role of glycosidic residues in antibiotic and antitumor activity and their randomization

A large number of antibiotics are glycosides. In numerous cases the glycosidic residues are crucial to their activity; sometimes, glycosylation only improves their pharmacokinetic parameters. Recent developments in molecular glycobiology have improved our understanding of aglycone vs. glycoside activities and made it possible to develop new, more active or more effective glycodrugs based on these findings - a very illustrative recent example is vancomycin. The majority of attention has been devoted to glycosidic antibiotics including their past, present, and probably future position in antimicrobial therapy. The role of the glycosidic residue in the biological activity of glycosidic antibiotics, and the attendant targeting and antibiotic selectivity mediated by glycone and aglycone in antibiotics some antitumor agents is discussed here in detail. Chemical and enzymatic modifications of aglycones in antibiotics, including their synthesis, are demonstrated on various examples, with particular emphasis on the role of specific and mutant glycosyltransferases and glycorandomization in the preparation of these compounds. The last section of this review describes and explains the interactions of the glycone moiety of the antibiotics with DNA and especially the design and structure-activity relationship of glycosidic antibiotics, including their classification based on their aglycone and glycosidic moiety. The new enzymatic methodology 'glycorandomization' enabled the preparation of glycoside libraries and opened up new ways to prepare optimized or entirely novel glycoside antibiotics.