School of Health Diet and Industry Management and Department of Nutrition, Chung Shan Medical University and Chung Shan Medical University Hospital, 110, Section 1, Jianguo N. Road, Taichung 402, Taiwan.
Food Chem Toxicol. 2012 Sep;50(9):3056-61. doi: 10.1016/j.fct.2012.06.011. Epub 2012 Jun 18.
The effects of scavenging 2, 2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radicals and inhibiting low-density lipoprotein (LDL) oxidation, and phenolic quantities were used for the activity-guided separation to identify the effective components of litchi flower. The acetone extract of the flower with notable antioxidant capacities was suspended in water and sequentially partitioned with n-hexane, ethyl acetate (EA) and n-butanol. The EA partition with the highest phenolic levels and antioxidant capacities was subjected to silica gel column chromatography. Thirteen fractions (Fr. 1-13) were collected; Fr. 10-12 with higher phenolic levels and antioxidant effects were applied to Sephadex LH-20 column chromatography. Each fraction was further separated into three sub-fractions and the second ones (Fr. 10-II, 11-II, and 12-II) were the best, which two major compounds could be isolated by semi-preparative high performance liquid chromatography (HPLC). Through Mass (MS) and Nuclear Magnetic Resonance (NMR) measurements, they could be identified as (-)-epicatechin and proanthocyanidin A2. Their contents in the litchi flower were 5.52 and 11.12 mg/g of dry weight, respectively. The study was the first time to reveal the effective antioxidant components of litchi flower.
利用清除 2,2-二苯基-2-苦肼基（DPPH）自由基和抑制低密度脂蛋白（LDL）氧化的作用以及酚类物质的含量，进行活性导向分离，以鉴定荔枝花的有效成分。具有显著抗氧化能力的花的丙酮提取物悬浮在水中，依次用正己烷、乙酸乙酯（EA）和正丁醇进行分配。酚类物质含量和抗氧化能力最高的 EA 部分进行硅胶柱层析。收集了 13 个馏分（Fr.1-13）；Fr.10-12 具有较高的酚类物质水平和抗氧化效果，应用于 Sephadex LH-20 柱层析。每个馏分进一步分离成三个亚馏分，第二馏分（Fr.10-II、11-II 和 12-II）效果最佳，其中两种主要化合物可以通过半制备高效液相色谱（HPLC）分离。通过质谱（MS）和核磁共振（NMR）测量，可以鉴定为（-）-表儿茶素和原花青素 A2。它们在荔枝花中的含量分别为 5.52 和 11.12mg/g 干重。该研究首次揭示了荔枝花的有效抗氧化成分。
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