Carbohydrate recognition of symmetrical tripodal receptor type tris(2-aminoethyl)amine derivatives

Carbohydrate recognition of some bioactive symmetrical tripodal receptor type tris(2-aminoethyl)amine (TAEA) derivatives was investigated. In calorimetric experiments, the highest binding constant (Ka) of compound C (C35H49N5O4S) with methyl alpha-d-mannopyranoside was Ka = 858 M-1 with 1:1 stoichiometry. Formation of hydrogen bonds in binding between symmetrical tripodal receptor type compound C and sugars was suggested by the large negative values of a dagger HA degrees (=-34 to -511 kJ mol(-1)). In a comparison of each set of alpha- and beta-anomers of some monosaccharides (methyl alpha/beta-d-galactopyranoside, methyl alpha/beta-d-glucopyranoside, and methyl alpha/beta-l-fucopyranoside), compound C showed that the binding constant of beta-anomer was larger than that of the corresponding alpha-anomer, indicating higher beta-anomer selectivity. The calculated energy-minimized structure of the complex of compound C with guest methyl alpha-d-mannopyranoside is also presented. The experimental results obtained from this work indicated that symmetrical tripodal receptor type TAEA derivative C has a lectin-like carbohydrate recognition property.