Antibacterial and Antioxidant Activities of Quercetin Oxidation Products from Yellow Onion (Allium cepa) Skin

By Freddy A. Ramos, Yoshihisa Takaishi, Miki Shirotori, Yousuke Kawaguchi, Koichiro Tsuchiya, Hirofumi Shibata, Tomihiko Higuti, Tetsuo Tadokoro, Minoru Takeuchi

July 28, 2017

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Title

Antibacterial and Antioxidant Activities of Quercetin Oxidation Products from Yellow Onion (Allium cepa) Skin

Author

Freddy A. Ramos, Yoshihisa Takaishi, Miki Shirotori, Yousuke Kawaguchi, Koichiro Tsuchiya, Hirofumi Shibata, Tomihiko Higuti, Tetsuo Tadokoro, Minoru Takeuchi

Year

2006

Journal

Journal of Agricultural and Food Chemistry

Abstract

Four new quercetin-derived oxidation products (1-4) and lunularin-4-O-â-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 â-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.

Full Article

http://pubs.acs.org/doi/abs/10.1021/jf060251c

Instrument

J-600

Keywords

Circular dichroism, Absolute configuration, Pharmaceutical, Agricultural and environmental