Degradation of hyaluronic acid powder by electron beam irradiation, gamma ray irradiation, microwave irradiation and thermal treatment: A comparative study

In this study, high molecular weight hyaluronic acid in powder form (HMW-HA, with average molecular weight of 1042 kDa) was degraded to low molecular (LMW-HA, 200–230 kDa) by several methods, and the changes in molecular structure and antioxidative activities brought about by each degradation method were compared. The degradation methods used were electron beam irradiation (EB), gamma ray irradiation (GM), microwave irradiation (MW), and thermal treatment (TH). The FT-IR spectra showed no substantial changes of the spectral pattern between HMW and LMW-HAs. However, the UV absorbance of LMW-HA by MW was considerably greater at 265 nm indicating the formation of more double bonds. The antioxidative activities of all LMW-HA samples were found to have risen, but the MW-treated LMW-HA showed the most significant increase due to a newly formed double bond. EB- and GM-treated LMW-HA showed the lowest polydispersity and little change in UV spectra from those of HMW-HA.