Synthesis and cytotoxicity of some d-mannose click conjugates with aminobenzoic acid derivatives

Abstract

Two sets of new conjugates obtained from d-mannose derivatives and o-, m-, and p-substituted benzoic acid esters interconnected through a triazole ring were synthesized by Cu(I) catalyzed azide–alkyne cycloaddition. All synthesized compounds were tested for their in vitro cytotoxic activity against seven cancer cell lines with/without multidrug resistance phenotype as well as non-tumor MRC-5 and BJ fibroblasts. Butyl ester of 4-aminobenzoic acid 6c showed the highest activity among all tested compounds, however, it was active only against K562 myeloid leukemia cells. N-Glycosyltriazole conjugates, both acetylated and nonacetylated at mannose moiety, were almost completely inactive. In contrast, some of the acetylated O-glycosyl conjugates showed cytotoxic activity which was cell line dependent and strongly affected by position of benzoic acid substitution as well as a length of its ester alkyl chain; the most potent compound was acetylated mannoside conjugated with octyl ester of m-substituted benzoic acid. However, deacetylation resulting in hydrophilicity increase of the glycosides almost completely abolished their cytotoxic potency.