本研究主要研究白肉火龍果和紅肉火龍果的抗氧化成分、抗氧化力與抗氧化功能。抗氧化成分主要分析花青素、多酚類、類黃酮、類胡蘿蔔素、單寧及卟啉類。抗氧化力則測定linoleic acid系統共軛雙烯生成抑制性。抗氧化功能包括：還原力、螯合亞鐵離子、清除DPPH自由基與清除超氧陰離子的能力。結果顯示紅肉火龍果含有顯著高量的類黃酮、花青素類、胡蘿蔔素與卟啉類，多酚類與單寧含量在兩者間則無顯著差異。在抗氧化力方面於2.5mg/mL濃度時以紅肉火龍果甲醇萃取物的抑制性顯著高於白肉火龍果；但在其他濃度時，兩者間無顯著差異。在抗氧化功能，紅肉火龍果甲醇萃取物的還原力和清除DPPH自由基的效應顯著高於白肉火龍果；兩者螯合亞鐵的能力則相當且在清除超氧陰離子的能力都較弱。
The aim of this study was to evaluate the antioxidative compositions, capacity and functions of Night-blooming Gereus (fruits of Hylocereus undatus and polyrhizus). The antioxidative compositions including polyphenols, flavonoids, anthocyans, carotenoids, tannins and porphyrins were determinated. The inhibition of conjugated dienes formation in linoleic acid emulsion autoxidation system was determined as antioxidative capacity. The antioxidative functions, such as reducing power, scavenging activity of DPPH radical, chelating effect with Fe(superscript 2+) ion and scavenging activity of superoxide anion, were determined. In results, H. polyrhizus had significantly higher flavonoids, anthocyans, carotenoids and porphyrins contents as compared to H. undatus. The content of polyphenols and tannins between two cultivars had no differences. H. polyrhizus had better inhibition percentage of conjugated dienes formation at 2.5 mg/mL in methanol extracts. The antioxidative functions, such as reducing power and scavenging effect of DPPH radicals were significantly higher in H. polyrhizus while there was no difference between two cultivars in chelating effect with Fe(superscript 2+) ion. Both cultivars had lower scavenging effect of superoxide anion.
