利用鄰近超臨界流體萃取技術測定海巴戟天抗氧化特性   全文下載

Determination of Antioxidative Properties of Morinda citrifolia Using Near Supercritical Fluid Extraction

基於對海巴戟天（Morinda citrifolia L.）內疏水性抗氧化物質的了解有限，以及超臨界二氧化碳（Supercritical fluid carbon dioxide）萃取技術被廣為熟知的許多優良特性，本研究利用鄰近超臨界二氧化碳萃取海巴戟天葉、青莖、褐莖與果實，並測定粗萃取液中的抗氧化特性。結果顯示在高壓低溫的鄰近超臨界二氧化碳萃取條件下，海巴戟天褐莖具有最高的總酚類含量（23.14 ± 1.83 mg/g），最佳的還原力（抗壞血酸當量為59.82 ± 6.28 mg/g），並具有最佳的總抗氧化力（TEAC ; Trolox 當量為564.52 ± 41.58 μmol/g）、DPPH 自由基清除能力。（半有效濃度，EC50 = 6.87 ± 0.14 mg/L）和清除超氧陰離子的能力（相當於超氧歧化?活性，SOD = 505.12 ± 26.68 SOD unit/g）。研究結果顯示抗氧化活性不僅來自酚類化合物，也來自於非極性的抗氧化物質；而海巴戟天褐莖是鄰近超臨界二氧化碳萃取方法中獲得抗氧化物質的一個重要的來源。

Limited knowledge is available regarding the hydrophobic antioxidants present in the Morinda citrifolia L (Noni). Moreover, supercritical fluid carbon dioxide (SF-CO2) extraction technique is well known with many superior extraction properties. The purpose of this study was to investigate the antioxidative properties of crude extracts from the leaves, green and brown stems, and fruit of Noni plant obtained by near SF-CO2 extraction. Extracts from brown stems by near SF-CO2 extraction under high pressure and low temperature conditions afforded the highest total phenolic content (23.14 ± 1.83 mg/g) and the best reducing power (59.82 ± 6.28 ascorbic acid equivalents mg/g). It also possessed the greatest antioxidative capacities, including Trolox equivalent antioxidant capacity assay (564.52 ± 41.58 μmol/g), scavenging of 2,2-diphenyl-1-picrylhydrazyl (effective concentration : EC50 = 6.87 ± 0.14 mg/L), and superoxide radical scavenging activity (505.12 ± 26.68 SOD unit/g), which indicated that the antioxidative activity is not only due to phenolic compounds but also due to non-polar antioxidants. Extracts from the brown stems of M. citrifolia could be a significant source of antioxidants when isolated by near SF-CO2 extraction.