The reactivity of various free radicals with hyaluronic acid: steady-state and pulse radiolysis studies.
The reactions of the primary water radicals with the biopolymer hyaluronic acid have been studied by pulse radiolysis. Bimolecular rate constants, expressed in terms of the disaccharide repeating sub-unit of hyaluronic acid, for OH., H. and eaq- were found to be 7 X 10(8) M-1 X s-1, 5 X 10(7) M-1 X s-1 and less than 5 X 10(6) M-1 X s-1, respectively. By comparing the viscosities of samples, gamma-irradiated in the steady state under a variety of conditions, with unirradiated controls, the efficiencies with which selected radicals cause chain breakage have been determined. Efficiencies of 30%, 15%, 0%, 0.2% and 5% were estimated for OH., H., eaq-, methanol radicals and tert-butanol radicals, respectively. The presence of oxygen during irradiation increased the extent of chain breakage by a factor of 1.75.
D004583:Electrons; D005609:Free Radicals; D005720:Gamma Rays; D006820:Hyaluronic Acid / Q000528:radiation effects*; D006878:Hydroxides; D010100:Oxygen; D011522:Protons; D011854:Radiochemistry; D014783:Viscosity; D014867:Water
D005609:Free Radicals; D006878:Hydroxides; D011522:Protons; D014867:Water; D006820:Hyaluronic Acid; D010100:Oxygen