He Xiangjiu, Liu Rui Hai
Department of Food Science and Institute of Comparative and Environmental Toxicology, Cornell University, Ithaca, New York 14853, USA.
J Agric Food Chem. 2008 Nov 12;56(21):9905-10. doi: 10.1021/jf8015255. Epub 2008 Oct 2.
Bioactivity-guided fractionation of Red Delicious apple peels was used to determine the chemical identity of bioactive constituents, which showed potent antiproliferative and antioxidant activities. Twenty-nine compounds, including triterpenoids, flavonoids, organic acids and plant sterols, were isolated using gradient solvent fractionation, Diaion HP-20, silica gel, and ODS columns, and preparative HPLC. Their chemical structures were identified using HR-MS and 1D and 2D NMR. Antiproliferative activities of isolated pure compounds against HepG2 human liver cancer cells and MCF-7 human breast cancer cells were evaluated. On the basis of the yields of isolated flavonoids (compounds 18- 23), the major flavonoids in apple peels are quercetin-3-O-beta-D-glucopyranoside (compound 20, 82.6%), then quercetin-3-O-beta-D-galactopyranoside (compound 19, 17.1%), followed by trace amounts of quercetin (compound 18, 0.2%), (-)-catechin (compound 22), (-)-epicatechin (compound 23), and quercetin-3-O-alpha-L-arabinofuranoside (compound 21). Among the compounds isolated, quercetin (18) and quercetin-3-O-beta-D-glucopyranoside (20) showed potent antiproliferative activities against HepG2 and MCF-7 cells, with EC 50 values of 40.9 +/- 1.1 and 49.2 +/- 4.9 microM to HepG2 cells and 137.5 +/- 2.6 and 23.9 +/- 3.9 microM to MCF-7 cells, respectively. Six flavonoids (18-23) and three phenolic compounds (10, 11, and 14) showed potent antioxidant activities. Caffeic acid (10), quercetin (18), and quercetin-3-O-beta-D-arabinofuranoside (21) showed higher antioxidant activity, with EC 50 values of <10 microM. Most tested flavonoids and phenolic compounds had high antioxidant activity when compared to ascorbic acid and might be responsible for the antioxidant activities of apples. These results showed apple peel phytochemicals have potent antioxidant and antiproliferative activities.
采用生物活性导向的方法对红富士苹果皮进行分离，以确定具有强抗增殖和抗氧化活性的生物活性成分的化学特性。通过梯度溶剂萃取、Diaion HP - 20、硅胶、ODS柱以及制备型高效液相色谱法，分离出了29种化合物，包括三萜类、黄酮类、有机酸和植物甾醇。利用高分辨质谱（HR - MS）以及一维和二维核磁共振（1D和2D NMR）对其化学结构进行了鉴定。评估了分离得到的纯化合物对HepG2人肝癌细胞和MCF - 7人乳腺癌细胞的抗增殖活性。基于分离得到的黄酮类化合物（化合物18 - 23）的产量，苹果皮中的主要黄酮类化合物是槲皮素 - 3 - O - β - D - 吡喃葡萄糖苷（化合物20，82.6%），其次是槲皮素 - 3 - O - β - D - 吡喃半乳糖苷（化合物19，17.1%），随后是痕量的槲皮素（化合物18，0.2%）、（ - ） - 儿茶素（化合物22）、（ - ） - 表儿茶素（化合物23）以及槲皮素 - 3 - O - α - L - 阿拉伯呋喃糖苷（化合物21）。在分离得到的化合物中，槲皮素（18）和槲皮素 - 3 - O - β - D - 吡喃葡萄糖苷（20）对HepG2和MCF - 7细胞显示出强抗增殖活性，对HepG2细胞的半数有效浓度（EC50）值分别为40.9±1.1和49.2±4.9 μM，对MCF - 7细胞的EC50值分别为137.5±2.6和23.9±3.9 μM。六种黄酮类化合物（18 - 23）和三种酚类化合物（10、11和14）显示出强抗氧化活性。咖啡酸（10）、槲皮素（18）和槲皮素 - 3 - O - β - D - 阿拉伯呋喃糖苷（21）表现出较高的抗氧化活性，EC50值<10 μM。与抗坏血酸相比，大多数测试的黄酮类化合物和酚类化合物具有较高的抗氧化活性，可能是苹果具有抗氧化活性的原因。这些结果表明苹果皮中的植物化学物质具有强抗氧化和抗增殖活性。
