红肉与白肉火龙果酚酸组成及其抗氧化活性

为研究火龙果果皮、果肉中的酚酸组成及抗氧化活性,以红肉火龙果和白肉火龙果为研究对象,采用高效液相色谱法(HPLC)测定其游离型酚酸(FPA)、可溶共价结合型酚酸(HPA)和束缚型酚酸(BPA)组分与含量,并测定其体外抗氧化活性,包括DPPH清除能力、还原能力和羟自由基抑制能力。结果表明:两种火龙果中酚酸含量顺序为:红肉果肉 > 白肉果肉 > 白肉果皮 > 红肉果皮。火龙果果肉中酚酸主要以HPA形式存在,果皮中酚酸的主要存在形式为BPA。没食子酸是红肉火龙果中的主要酚酸(1700.70 μg/g干重);原儿茶酸是白肉火龙果中主要酚酸(1877.50 μg/g干重)。红肉果皮的BPA对DPPH自由基清除能力最强(2206.37 mg/L),红肉果肉的HPA还原能力最强(A₇₀₀=0.82),白肉果皮的HPA对羟自由基抑制能力最强(77.50 U/mL)。酚酸含量与抗氧化活性的相关性分析表明:DPPH自由基清除能力和还原能力与酚酸的含量呈极显著(P<0.01)正相关,羟自由基抑制能力与酚酸含量无显著相关性。

Components and Antioxidant Activity of Phenolic Acids in Red and White Pitaya

The free phenolic acids(FPA),soluble covalent phenolic acids(HPA) and bound phenolic acids(BPA) were extracted and analyzed by high performance liquid chromatography(HPLC),and the antioxidant activities of phenolic acids(PAs),which including 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical scavenging capacity,ferric reducing power and hydroxyl radical inhibiting capacity were determined. The results showed that the contents of PAs showed the following tendency:Red pulp > white pulp > white peel > red peel. The HPA was the main PAs in pulp and the BPA was the main PAs in peel of pitaya. Gallic acid(1700.70 μg/g DW) was the dominated PAs in red pitaya,and protocatechuic acid(1877.50 μg/g DW) was the dominated PAs in white pitaya. The BPA of red peel possessed the highest DPPH radical scavenging capacity(2206.37 mg/L),HPA of white pulp had the strongest reducing ability(A₇₀₀=0.82) and HPA of white peel owned the uppermost hydroxyl radical inhibiting capacity(77.50 U/mL). The correlation analysis of contents and antioxidant activities showed that DPPH scavenging ability and ferric reducing power were significantly(P<0.01) correlated with PAs contents,while hydroxyl radical inhibiting capacity was independent of the PAs contents.