龍眼種子的萃取物被發現含有高含量有效的植物多酚類化合物，諸如鞣花酸、沒食子酸等，植物多酚類曾被發表過可表現生物活性及明顯抗氧化活性和自由基的清除活性。因為之前的研究龍眼種子大多採用傳統的水萃及有機溶劑萃取，因此本實驗將龍眼種子除了採用純水、50%乙醇方法萃取之外，特別採用了超臨界二氧化碳萃取法。
經由高速液相層析/質譜儀及紫外光法分析後，發現傳統純水、50%乙醇萃取方法所萃出的成份相近，大部份成份皆在滯留時間二十分鐘前出現，而超臨界二氧化碳萃取法所萃出的成份，在滯留時間二十分鐘後出現一些特別波峰，可能是一些不同成份的未知化合物，我們測試三種萃出物的抗發炎活性，發現不同方法的萃取物，其抗發炎的生物活性濃度有差異，但做濃度調整後，皆具有抗發炎的生物活性。所以我們進一步評估超臨界二氧化碳萃取法所萃出的成份是有別於其他萃取方法，而其高壓低溫的萃取方法確實可保留對熱不穩定的成分，進而可發現新的活性成分，同時以高效液相層析/質譜儀作為龍眼種子不同萃出方法所萃出成份的分析平台，可延伸應用於其他中、草藥萃出物的分析。 The longan seed extracts, such as corilagin, gallic acid and ellagic acid, are implicated with potent antioxidant biological properties. In this study, we evaluated the content and bioactive properties of polyphenolic compounds extracts from longan seeds by using three different extract methods, including the hot water extraction, 50% ethanol extraction and carbon dioxide supercritical fluid extraction (SFE). The crude extracts were analyzed by reversed-phase HPLC with UV detection at 270 nm and mass spectrometry. The major components were identified as gallic acid, and ellagic acid. Concentrations of gallic acid and ellagic acid in three extracts were determined using HPLC/UV (range from 1 to 100 µg /mL) with external standard calibration. The analyses showed that there was not significant variation in the contents of gallic acid and ellagic acid in different extracts. The extracts from SFE contained the more nonpolar compounds comparing with the other two methods.
Possible antiinflammatory effects of crude extracts were examined by assessing their effects on NO production in the cell line RAW 264.7. The results indicated that three crude extracts inhibited the iNOS protein synthesis in a concentration-dependent manner.
