A new cyclic pentasaccharide comprising an oxymethylene glycosidic bond connecting the individual α- d -glycopyranoside monomers is synthesized through cycloglycosylation of a linear pentasaccharide precursor, which, in turn, is synthesized through the block glycosylation method. Molecular modeling shows that the 30-membered macrocyclic pentasaccharide is a distorted ellipsoid structure, with the lower and upper rims occupied by secondary and primary hydroxyl groups, respectively. Following the synthesis, the microenvironment of the cyclic pentasaccharide is assessed through thermodynamic evaluation upon complexation with 1-aminoadamantane in an aqueous solution, which shows the formation of ∼1:2 host-to-guest complex and a binding affinity of 10 500 (±425) M –1 . Synthesis and assessment of the host–guest binding property of the new glycosidic bond expanded cyclic pentasaccharide are presented.

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Immense interest on studies and applications of naturally-occurring cyclic oligosaccharides has attracted novel methods and ingenuities in their chemical synthesis. The conformation of the monosaccharides constituting the macrocyles is important, in order to permit cyclization and facilitate the macrocyclic supramolecular properties. Synthesis of small-ring cyclic oligosaccharides combining the structural and functional features continues to be a challenge. This review article assesses the current chemical methods for the synthesis of small-ring cyclic oligosaccharides, particularly, macrocycles that possess five or fewer monomer units constituting the macrocycle. Methods to retain the stable conformation of individual sugar units on small-ring macrocyles and the benefits to supramolecular properties are discussed.

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Lipomannan and lipoarabinomannan are integral components of the mycobacterial cell wall. Earlier studies demonstrated that synthetic arabinan and arabinomannan glycolipids acted as inhibitors of mycobacterial growth, in addition to exhibiting inhibitory activities of mycobacterial biofilm. Herein, it is demonstrated that synthetic mannan glycolipids are better inhibitors of mycobacterial growth, whereas lipoarabinomannan has a higher inhibition efficiency to biofilm. Syntheses of mannan glycolipids with a graded number of mannan moieties and an arabinomannan glycolipid are conducted by chemical methods and subsequent mycobacterial growth and biofilm inhibition studies are conducted on Mycobacterium smegmatis. Growth inhibition of (73±3) % is observed with a mannose trisaccharide containing a glycolipid, whereas this glycolipid did not promote biofilm inhibition activity better than that of arabinomannan glycolipid. The antibiotic supplementation activities of glycolipids on growth and biofilm inhibitions are evaluated. Increases in growth and biofilm inhibitions are observed if the antibiotic is supplemented with glycolipids, which leads to a significant reduction of inhibition concentrations of the antibiotic.