Two new phenolic compounds, 1-
O-(2,6-dimethoxy-4-hydroxyphenyl)-
β-D-glucopyranoside, named leonuriside A and
β-(3,4-dihydroxyphenyl)-ethyl-
O-
α-L-arabinopyranosyl-(1→2)-
α-L-rhamnopyranosyl)-(1→3)-D-glucopyra-noside, named leonuriside B were isolated from Leonurii Herba (dried whole part of
Leonurus japonicus) along with four known flavonol glycosides, rutin, isoqeurcitrin, tiliroside and isorhamnetin 3-
O-rutinoside, and a known iridoid glycoside, leonuride. Their structures were elucidated on the basis of physical and spectroscopic data. Subsequent anti-oxidative assay of these compounds using the ferric thiocyanate method revealed that they, except for leonuride, have stronger anti-oxidative activities than that of
α-tocopherol. Moreover, the four flavonol glycosides and leonuriside A were identified as stronger antioxidants than 3-
tert.-butyl-4-hydroxyanisole.
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