Novel oxadiazole thioglycosides as potential anti-Acinetobacter agents

The glycosylation of 1,3,4-oxadiazole-2-thiones has been performed with peracetylated
β-pyranosyl bromide in the presence of potassium carbonate. Deprotection of acetylated
thioglycosides was necessary for increasing their antibacterial effects. The structures of
nucleosides were confirmed by 1H NMR, 13C NMR and HRMS. The anomeric protons of
nucleosides c1–4 were assigned to the doublet, confirming the β-configuration. The synthesized
compounds were tested for their antimicrobial activity against Acinetobacter calcoaceticus
(Gram-negetive) strain in-vitro in comparison with Ampicillin as a reference drug which
is normally used for treating such infections. The synthetic compounds showed different
inhibition zones against tested bacterial strain. Thioglycoside derivatives of 1,3,4-oxadiazole-
2-thiones (c set) were more active against Acinetobacter calcoaceticus ATCC 23055 than
“parent” 1,3,4-oxadiazole-2-thiones (a set), confirming the relation between glyco-conjugation
and increasing of antiproliferative activity of antibiotic agents. The best result belonged to
nucleoside bearing 2-furyl moiety in its heterocyclic nucleus (c4). The existence of m-PhNO2
group as Ar in structures of a set and their corresponding sugar derivatives decreased the
antibacterial activity of them in comparison with the rest of synthetic compounds