DEGRADATION OF HYALURONIC-ACID AT THE METAL-SURFACE

When the viscosity of hyaluronic acid (HA) solution was measured with a rotational viscometer, depolymerization occurred only by leaving the sample in the cup of the viscometer, while the solution in a glass te st tube at the same temperature, 37 degrees C, was practically stable during the entire period of investigation. As the parts where the samp le solution had contact with the viscometer are stainless steel, the p articipation of metal ions in the depolymerization was suspected. Ther efore, experiments were carried out with stainless-steel beads in the KA solution. The results show that the molecular weight of HA decrease d on exposure to the beads under aerobic conditions. The addition of 1 0 beads to 2 ml of a 0.1% HA solution prepared with 0.2 M NaCl reduced the molecular weight to about 75% of the initial value after 4 h. The degradation rate was proportional to the surface area of the beads. H owever, no dissolution of metal ion was detected, and therefore, this reaction was thought to proceed at the surface of the metal.