Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
J Agric Food Chem. 2011 Jun 8;59(11):5927-34. doi: 10.1021/jf104798n. Epub 2011 May 12.
The main flavonoids were isolated from three selected onion cultivars. Three phenolic compounds were obtained by reverse-phase HPLC, and their structures were elucidated by multiple NMR measurements. There were two known compounds, quercetin and quercetin 3'-O-β-D-glucopyranoside (Q3'G), and one novel compound, quercetin 3-O-β-D-glucopyranoside-(4→1)-β-d-glucopyranoside (Q3M), which was identified in onion for the first time. These flavonoids were found to be more abundant in the onion peel than in the flesh or core. Their antioxidative activities were tested using the DPPH method, and their antiaging activities were evaluated using a Caenorhabditis elegans lifespan assay. No direct correlation was found between antioxidative activity and antiaging activity. Quercetin showed the highest antioxidative activity, whereas Q3M showed the strongest antiaging activity among these flavonoids, which might be related to its high hydrophilicity.
主要类黄酮从三种选定的洋葱品种中分离出来。通过反相 HPLC 获得了三种酚类化合物，并通过多次 NMR 测量阐明了它们的结构。有两种已知的化合物，槲皮素和槲皮素 3'-O-β-D-吡喃葡萄糖苷（Q3'G），以及一种新的化合物，洋葱中首次发现的槲皮素 3-O-β-D-吡喃葡萄糖苷-(4→1)-β-D-吡喃葡萄糖苷（Q3M）。这些类黄酮在洋葱皮中比在果肉或芯中更为丰富。使用 DPPH 法测试了它们的抗氧化活性，并使用秀丽隐杆线虫寿命测定法评估了它们的抗衰老活性。抗氧化活性和抗衰老活性之间没有直接的相关性。在这些类黄酮中，槲皮素表现出最高的抗氧化活性，而 Q3M 表现出最强的抗衰老活性，这可能与其高亲水性有关。
