| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 96 === In this study, Gracilaria tenuistipita, a common macro–alga in Taiwan, is investigated for its antioxidant capacity and antitumor activity after sulfated and composite particles formation. The polysaccharides extracted from Gracilaria tenuistipita were sulfated by the sulfation process. Their sulfated content increased from 4% to 24%. The composite particles made by ionic interactions between chitosan (MW=100 kDa) and native Gracilaria polysaccharides (CNGPE) and sulfated Gracilaria polysaccharides (CSGPE). CNGPE and CSGPE have average particles diameters of 180 and 120 nm with an entrapment efficiency of 59 and 43%. For SGPE at 10000 μg/mL concentration, its ascorbic acid equivalent was 308 μg. Its scavenged DPPH radical, superoxide, chelating capacity was 40, 80, and 90%, respectively. This was higher than those of NGPE, CNGPE and CSGPE at the same concentration. In reducing power assay, SGPE was slightly higher than other samples. The MTT assay of RAW 264.7 cell line indicated that no obvious toxicity of high concentration samples. To Caco-2 cell line, the IC50 value of CNGPE, SGPE and CSGPE was 90, 88 and 40 μg/mL, respectively. To COLO 201 cell line, the IC50 value have not been observed. To HT-29 cell line, the IC50 value of NGPE and SGPE was 50 and 35 μg/mL, respectively. The antitumor activities of composite particle have not been observed, might be that the composite particles prepared by ionic interactions between chitosan and Gracilaria polysaccharides did not show any improvement. Furthermore, NGPE, CNGPE, SGPE and CSGPE was shown induce apoptosis by upregulating the caspase-9 activity. Among all the experiment results, high sulfated content could improve the biological activities and contribute to the apoptosis of HT–29 that is triggered by activating caspase-9 enzyme.
|
|---|
