論文名稱:

超臨界二氧化碳萃取洛神花多酚成分及其抗氧化活性

Study on the relationships between polyphenols components and antioxidant activities in Hibiscus sabdariffa Linnaeu supercritical carbondioxide fluid extracts

研究生:

卓玠宏

指導教授:

周  波

高而仕

          學號:

98017011

畢業學年度:

99

      出版年:

民100

關鍵字:

超臨界二氧化碳萃取 supercritical carbon dioxide extraction method

洛神花 Hibiscus sabdariffa Linnaeus

多酚 polyphenol

咖啡酸 caffeic acid

抗氧化 antioxidant

摘要:

氧化碳超臨界萃取技術具有較低溫度，高擴散能力之特性，可將天然物中的熱不穩定性物質萃出，並保留活性成分，所以本研究以二氧化碳超臨界流體萃取技術萃取洛神花多酚類物質咖啡酸。洛神花所含有的多酚類物質具有許多的生物活性，其中的有效成分咖啡酸，具備有抗氧化、捕捉自由基、抑制酪氨酸酶的功能。高效能液相層析儀分析水萃取法、乙醇萃取法、二氧化碳超臨界流體萃取法對於洛神花的咖啡酸萃取效率。結果發現使用水萃取法與酒精萃取法均能將咖啡酸完全萃取出來，使用二氧化碳超臨界流體萃取法萃取出來的咖啡酸含量稍低，但是高效能液相層析儀的分析圖譜顯示使用二氧化碳超臨界流體萃取法的萃取物成分較為單純。另外將不同比例的水、乙醇作為共溶劑添加至二氧化碳超臨界流體中進行修飾，並且改變不同的臨界壓力、臨界溫度、與超臨界流體的流速藉此評估使用共溶劑修飾的超臨界流體萃取洛神花咖啡酸效率的最佳化條件。實驗結果發現，提高咖啡酸的萃取條件需要降低臨界壓力、提高臨界溫度、增加修飾共溶劑加入二氧化碳超臨界流體的流速、並且同時使用含有水與乙醇當作修飾共溶劑。根據高效能液相層析儀針對萃取物的咖啡酸含量分析結果，可以得到的最佳化萃取條件為臨界壓力250 bar、臨界溫度40℃、共溶劑乙醇濃度85%、共溶劑流量1.2 ml/min。總合全部的實驗結果，可以得知以水和酒精當作共溶劑進行修飾可以在二氧化碳超臨界流體中提高針對咖啡酸的萃取效率，但是水分含量過高容易使二氧化碳超臨界流體的狀態不穩定而形成次臨界流體，加入乙醇為修飾共溶劑則可以進一步穩定含有水分的二氧化碳超臨界流體，因此同時以兩種以上的共溶劑對二氧化碳超臨界流體進行修飾，是提高咖啡酸萃取效率的關鍵。在抗氧化活性當中，其氧化還原能力、清除DPPH自由基及酪氨酸酶之能力測定發現當咖啡酸萃取率上升，清除DPPH自由基則提升，而氧化還原能力上咖啡酸萃取率也頗佳，但酪氨酸酶能力上，則看不出相同趨勢，但在HPLC圖譜上較複雜，可能萃取出含有較優異抑制酪氨酸酶之成分。

Supercritical carbon dioxide (SC-CO2) can provide a benefit of lower temperature and high diffusion ability in nature product extraction process, not only preserved the thermo unstable but also keep the bioactivity of the extracts. Owing to this, we use supercritical carbon dioxide extract the caffeic acid (CA), a kind of polyphenol, from Roselle. Caffeic acid has abilities with antioxidant, radical catching and tyrosinase inhibition. We also use high performance liquid chromatography analysis the components differences between water extraction, alcohol extraction and supercritical carbon dioxide extraction. The result show that caffeic acid was complete extracted by water and alcohol extraction, but lower in supercritical carbon dioxide extraction. The components of supercritical carbon dioxide extraction are much simple. Following, we add water and alcohol as the co-solvent to modify the polarity of the supercritical carbon dioxide, and use this modified supercritical carbon dioxide in the caffeic acid extraction with differ critical temperatures, critical pressures and flow rates. In the results of the further analysis by high performance liquid chromatography, the best optimization in modified supercritical carbon dioxide extraction of caffeic acid needs critical pressure at 250 bar, critical temperature at 40℃, Co-solvent 85% ethanol as co-solvent at the flow rate 1.2ml/min. In conclusion, add water and alcohol as co-solvent into supercritical carbon dioxide can optimize the caffeic acid extraction efficiency from Roselle. Actually, add only water into supercritical carbon dioxide will make supercritical unstable and become sub-supercritical. Adding alcohol can provide a better stability when water is a necessary co-solvent to the supercritical carbon dioxide extraction. Both adding water and alcohol as co-solvents are the key point of increasing the efficiency of caffeic acid supercritical carbon dioxide extraction from Roselle.