Xiao Hang, Parkin Kirk
Department of Food Science, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
J Agric Food Chem. 2006 Nov 1;54(22):8417-24. doi: 10.1021/jf061582s.
The objective of the study was to isolate and identify potential cancer preventive constituents from green onion based on the ability to induce quinone reductase (QR, a representative phase II enzyme) in murine hepatoma cells (Hepa 1c1c7). Crude nonpolar solvent extracts were prepared from freeze-dried green onion by sequential refluxing with hexane and then ethyl acetate, followed by liquid-liquid extraction. Active fractions were subjected to the Hepa 1c1c7 bioassay-guided steps of flash chromatography, thin layer chromatography (TLC), and high-pressure preparative liquid chromatography (HPLC) to afford pure isolates capable of inducing QR. Multiple fractions were active in inducing QR. Five pure compounds were isolated from active fractions and identified using spectroscopic methods; these were p-hydroxyphenethyl trans-ferulate (1), 5,6-dimethyl-2-pyridinecarboxylic acid (2), ferulic acid (3), 1-(6-hydroxy-[3]pyridyl)-propan-1-one (4), and N-trans-feruloyl 3-O-methyldopamine (5). p-Hydroxyphenethyl trans-ferulate (1) doubled QR specific activity in Hepa 1c1c7 cells at a level of 2.1 microg/mL (6.6 microM).
本研究的目的是基于在小鼠肝癌细胞（Hepa 1c1c7）中诱导醌还原酶（QR，一种代表性的Ⅱ相酶）的能力，从青葱中分离并鉴定潜在的癌症预防成分。通过依次用己烷和乙酸乙酯回流冻干的青葱制备粗非极性溶剂提取物，然后进行液-液萃取。活性组分经过快速色谱、薄层色谱（TLC）和高压制备液相色谱（HPLC）等Hepa 1c1c7生物测定指导步骤，以获得能够诱导QR的纯分离物。多个组分在诱导QR方面具有活性。从活性组分中分离出5种纯化合物，并采用光谱方法进行鉴定；它们分别是对羟基苯乙基反式阿魏酸酯（1）、5,6-二甲基-2-吡啶羧酸（2）、阿魏酸（3）、1-（6-羟基-[3]吡啶基）-丙-1-酮（4）和N-反式阿魏酰基3-O-甲基多巴胺（5）。对羟基苯乙基反式阿魏酸酯（1）在2.1μg/mL（6.6μM）的水平下使Hepa 1c1c7细胞中的QR比活性增加了一倍。
