Molecules 2012, 17, 5459-5466; doi:10.3390/molecules17055459
Isolation and Characterization of Phenolic Antioxidants from
Yoshiaki Amakura *, Ayako Yoshimura, Morio Yoshimura and Takashi Yoshida
College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama,
Ehime 790-8578, Japan; E-Mails: firstname.lastname@example.org (A.Y.);
email@example.com (M.Y.); firstname.lastname@example.org (T.Y.)
* Author to whom correspondence should be addressed; E-Mail: email@example.com;
Tel.: +81-89-925-7111; Fax: +81-89-926-7162.
Received: 12 April 2012; in revised form: 2 May 2012 / Accepted: 4 May 2012 /
Published: 9 May 2012
Abstract: Seven phenolic compounds, including a new phenylethanoid glycoside, were
isolated from the ethyl acetate fraction of an aqueous ethanol extract of Plantago Herb
(whole part of Plantago asiatica L.), which showed significant antioxidative activity. The
new compound was characterized as 2-(3,4-dihydroxyphenyl)ethyl 3-O-β-D-allopyranosyl-
6-O-caffeoyl-β-D-glucopyranoside on the basis of spectral and chemical evidence, and its
antioxidant activity was comparable to that of tea catechins.
Keywords: Plantago asiatica; Plantaginaceae; phenylethanoid glycoside; antioxidant;
oxygen radical absorbance capacity (ORAC)
The genus Plantago consists of more than 200 species, most of which are small plants with elliptic
leaves and small spikes of very small flowers. Plantago asiatica L. (Plantaginaceae) is a weed widely
distributed in eastern Asia. The aerial parts of P. asiatica, ‘Plantago Herba’, are used as a crude drug in
China, Korea, and Japan for diuretic, antitussive, expectorant, and antiphlogistic purposes .
In Japan, it is an official medicine listed in the Japanese Pharmacopeia as the crude drug “Plantago
Herb” . It has also been commercialized as a dietary supplement in various forms, such as a tea.
Polyphenols such as phenylethanoid glycosides and flavonoids, together with iridoid glucosides, were
reported as components of the aerial parts of this plant . Plantamajoside, a phenylethanoid of the
Molecules 2012, 17
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Sample Availability: Sample of the compound 4 is available from the authors.
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