Synthesis and swelling-dependent enzymatic degradation of borax-modified guar gum for colonic delivery purposes

Guar gum is a natural, low water-soluble polysaccharide which is widely used as a thickening agent in the food and pharmaceutical industries. As a pharmaceutical adjuvant, it may be used for colon-specific purposes because of its reported degradation in the human large intestine. In this work, guar gum is used as a model in which we examined whether its fluid uptake properties could be increased by a chemical modification to enhance its enzymatic degradation. The guar gum was reacted with increasing amounts of borax, and the properties of the new polymers were characterized by viscosity measurements prior to drying, atomic absorption, Fourier transform infrared spectroscopy, water solubility measurements, and equilibrium water uptake measurements. It was found that, despite the reaction with borate, solid guar gum (either in film form or compressed tablets) maintained its ability to degrade by galactomannanase. The modified products were found to possess better swelling properties and, as a result, better enzymatic degradation. The increase in the polymer biodegradation was directly proportional to the increase in their fluid uptake characteristics.