Technology and Properties of Chondroitin Sulfate from Marine Hydrobionts

Abstract

Chondroitin sulfate was isolated from the cartilage tissue of salmon (Salmo salar), northern skate (Raja hyperborean) and black-shark (Galeus melastomus). The polysaccharide content is from 67.1% to 82.2% in the samples. FTIR spectra of the obtained samples contain peaks at wave numbers characteristic of chondroitin sulfates (1550, 1350–1300, 1160–1120 и 822 cм–1). The thermal properties of chondroitin sulfates were studied by differential thermogravimetry. It was shown that the weight loss of the samples in the temperature range of 40–600ºC occurs in several stages. At the first stage, desorption of physically bound water occurs to a temperature of 150–200ºC, which can be explained by the difficulty in breaking hydrogen bonds between water molecules and the polar functional groups of chondroitin sulfate. Thermal decomposition of the bulk of chondroitin sulfate samples is observed at temperatures from 230–530ºC. The presence of peaks on the TGA curves in the temperature range 236–330ºC is associated with the release of sulfate groups and carboxylic acids (thermal destruction of uronic acid and pyranose units). When samples are heated above 350–400ºC, thermal oxidative degradation of residual carbon and sulfur compounds develops. The mass loss rates in each region were determined and the activation energies of each event were calculated. The nature of the cartilage tissue from which chondroitin sulfate is isolated affects the rate of destruction. Thus, in the temperature range 236–244ºC, the lowest destruction rate is observed for samples of chondroitin sulfate from salmon cartilage.