Ramos Freddy A, Takaishi Yoshihisa, Shirotori Miki, Kawaguchi Yousuke, Tsuchiya Koichiro, Shibata Hirofumi, Higuti Tomihiko, Tadokoro Tetsuo, Takeuchi Minoru
Graduate School of Pharmaceutical Sciences, University of Tokushima, Shomachi-l-78-1, Tokushima 770-8505, Japan.
J Agric Food Chem. 2006 May 17;54(10):3551-7. doi: 10.1021/jf060251c.
Four new quercetin-derived oxidation products (1-4) and lunularin-4-O-beta-D-glucoside (5) were isolated from a water extract of onion (Allium cepa) skin, together with 17 other known compounds. Antibacterial assays for the isolated compounds showed that 2-(3,4-dihydroxyphenyl)-4,6-dihydroxy-2-methoxybenzofuran-3-one (1) presented selective activity against Helicobacter pylori strains and 3-(quercetin-8-yl)-2,3-epoxyflavanone (4) showed antibacterial activity against MRSA and H. pylori strains at the same time that it increased susceptibility of MRSA to beta-lactams. Evaluation of antioxidant activity against DPPH for the isolated compounds showed that the new derivative compounds (1-4) and 2,5,7,3',4'-pentahydroxy-3,4-flavandione (6) are more active than quercetin.
从洋葱（葱属植物）皮的水提取物中分离出四种新的槲皮素衍生氧化产物（1-4）和半月苔黄素-4-O-β-D-葡萄糖苷（5），以及其他17种已知化合物。对分离出的化合物进行抗菌试验表明，2-(3,4-二羟基苯基)-4,6-二羟基-2-甲氧基苯并呋喃-3-酮（1）对幽门螺杆菌菌株具有选择性活性，3-(槲皮素-8-基)-2,3-环氧黄烷酮（4）对耐甲氧西林金黄色葡萄球菌（MRSA）和幽门螺杆菌菌株均显示抗菌活性，同时它还增加了MRSA对β-内酰胺类药物的敏感性。对分离出的化合物进行的DPPH抗氧化活性评估表明，新的衍生物化合物（1-4）和2,5,7,3',4'-五羟基-3,4-黄烷二酮（6）比槲皮素更具活性。
