Investigation of interactions in 4-aminosalicylic acid/polysaccharide in aqueous media

Wide angle X-ray diffraction patterns, differential scanning calorimetry, UV–vis spectra and steady-state fluorescence spectroscopy were used to examine the interactions of konjac glucomannan (KGM) and 4-aminosalicylic acid (4-ASA) in aqueous solutions. The results showed that there exist hydrogen bonds between 4-ASA and KGM, and the presence of KGM can cause the fluorescence quench in 4-ASA aqueous solution. The association constant of Ka is 77.32 L/mol, and the number of binding sites per sugar-ring is 0.94 (R = 0.991). The value 0.94 indicates1:1 complexation of the drug of 4-ASA with sugar-ring on the chain of KGM. These results provide useful information for the practical application of these 4-ASA-polysaccharide systems in food and pharmaceutical industries.