| Summary: | 博士 === 國立屏東科技大學 === 食品科學系所 === 100 === Malignant tumor is the first one of the ten causes of death in the past 20 years in Taiwan. No method was found to eradicate the recurrence, aggregation or metastasis of cancer cells nowadays. Hence, the studies on innocuous components with cancer curing abilities from natural plants are valuable, practical, and academic work. Recently, a natural substance, pectin, of peel and pulp in citrus fruits such as lemon, grapefruit, orange, and tangerine, was reported to be breakdown into shorter unbranched galacturonic acid chain, modified by pH adjustment, namely modified citrus pectin (MCP) that exhibited more soluble and easier absorption by the human body. It can inhibit the adhering of cancer cell on the surface of host cells and then suppress the metastasis of cancer cells. In addition, pectin was also found to express a lot of biological activities such as metals ion removing, blood glucose reducing, cholesterol levels reducing, nitric oxide synthase (iNOS) inhibition and cyclooxygenase-2 (COX-2) inhibition for anticancer and anti-inflammation. Due to the characteristics, decomposition and modification of pectin, of pectin lyase, pectinesterase and polygalacturonase and the reaction rate of enzyme (turning over number) is greater than chemical modification. Therefore, this study will research on two part: The first part, the antioxidant activity of pectic enzyme modified pectin and to find out the best modified conditions. The second part, the inhibition of tumour cells (in vitro) by pectin enzyme treated pectin will be evaluated, the anti-tumor mechanism and anti-metastasis will be investigated as well. In antioxidant capacity: PET-pectin with 1 kDa and 11.6% DE expressed more antioxidant activity (DPPH radical scavenging activity, TEAC, and reducing power) than untreated citrus pectin (with 353 kDa and 60% DE). In addition, TEAC was found to be positively associated with mw of PET-pectin and negatively associated DE of PET-pectin. The addition of PET-pectin could increase the EA, ES, and oxidative stability of SPI-stabilized O/W emulsion. The inhibition of tumour cells (in vitro): PET-pectin was found to be absorbed by BALB/c mouse and human tumor cells and caused an increase in the membrane permeability and damage of human hepatoma HepG2, human lung carcinoma A549, and human colon carcinoma Colo 205, while the growth inhibition of human normal embryonic kidney HEK293 almost was not affected by PET-pectin. The result showed that CPE hydrolysis did increase the lipid oxidation inhibition ability, emulsion stabilizing effect, and antitumor activity of citrus pectin and can be one alternative choice of food processing for functional enhancing. Hence, the citrus PET-pectin can be considered to develop as a natural dietary supplement or food ingredient for human cancer prevention.
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