Effect of adding galactomannans on some physical and chemical properties of hyaluronic acid

Hyaluronic acid (HA) and galactomannans (such as guar gum - GG and locust bean gum - LBG) are biomacromolecules with various applications due to their physicochemical characteristics in solution, especially their ability to form films or hydrogels in some conditions. Some of these applications are possible because they are nontoxic and biocompatible. Mixtures of HA and GG or LBG, at pH 7.4, were prepared at 25 g·L^-1 of HA:LBG or HA:GG with percentages of 50:50, 60:40, 70:30 and 80:20 (w/w) and evaluated by rheology and NMR experiments regarding the interactions. The best synergism observed was between HA:LBG, most pronounced at 50% (w/w), where the dynamic modulus values G' and G″ indicated the formation of physical gels with viscoelastic behavior close to that of HA. 2D NOESY spectra revealed hydrogen interconnectivity of H-1 glucuronic acid units of HA with H-5 mannose units of the main galactomannan chains. This synergism, besides producing a hydrogel with interesting properties, also can decrease the cost by partially replacing HA in many applications, such as in nutraceutical foods, support for tissue engineering and cosmetics.