THE ANTIOXIDANT ACTIVITIES OF ACID HYDROLYSIS OF κ-Carrageenan

Carrageenans are naturally sulphated polysaccharides produced by primary metabolism in red seaweed (Rhodophyceae). Carrageenans are thought to be a good source of antioxidants. The antioxidant activity of commercial κ-Carrageenan and degraded κ-Carrageenan will be determined in this investigation. Hydrochloric acid was used to hydrolyzed κ-Carrageenan. A 3500 Da molecular weight dialysis tube was also used to separate the filtrate (MW 3500 Da). UV-Vis, FTIR, and GC-MS spectroscopies were used to analyze the chemical and spectral properties of commercial Carrageenan and its degradation products. The antioxidant activity of the compounds was determined using 2,2-diphenyl-2-picryl-hydrazyl (DPPH) and compared to vitamin C as a standard using UV at a wavelength of 517 nm in the concentration range of 200 - 800 ppm. The chemical structure of the degraded κ-Carrageenan was disclosed by FTIR analysis, which demonstrated a decrease in the intensity of the sulfate peak and the production of new carbonyl groups. Hexadecanoic acid ethyl ester, 1,2-benzenedicarboxylic acid, 9,19-Cyclo-9β-lanostan-3β-ol, 24-methylene-, and (E,E,E,E,E,E)-(1)-2,6,10,15,19,23-hexamethyltetracosa-1,6,10,14,18,22-hexaen-3-ol were found in the GC-MS. Analysis antioxidant activities of commercial κ-Carrageenan, degraded κ-Carrageenan with a molecular weight over 3500 Da, and κ-Carrageenan with a molecular weight below 3500 Da, respectively, have range percent inhibition from 7.83 - 13.58%, 32.64 - 42.28%, and 26.63% - 34.99%. Vitamin C, on the other hand, has a percent inhibition of 97.65% - 99.48%