Anti-Oxidative Constituents from Leonurii Herba (Leonurus japonicus).

Abstract

Two new phenolic compounds, 1-O-(2,6-dimethoxy-4hydroxyphenyl)-P-D-glucopyranoside, named leonuriside A and p-(3,~hd ihydroxyphenyl)-ethyl-O-a-L-arabinopyranosyl-(1-> 2)-a-L-rh amnopyranosyl)-(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, Ieonuride. 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 a-tocopherol. Moreover, the four flavonol glycosides and leonuriside A were identified as stronger antioxidants than 3-tert.-butyl-lhhydroxyanisole.