Anti-oxidant Constituents of the Roots and Stolons of Licorice (Glycyrrhiza glabra)

As part of a search for new cancer chemopreventive agents, a new chalcone derivative ( 1 ), a novel group of neolignan lipid esters ( 2 ), and seven known phenolic compounds (formononetin, glabridin, hemileiocarpin, hispaglabridin B, isoliquiritigenin, 4‘- O -methylglabridin, and paratocarpin B) ( 3 − 9 ) were isolated from the roots and stolons of licorice ( Glycyrrhiza glabra ). The structures of compound 1 and the individual components of isolate 2 were elucidated using various spectroscopic and chemical methods. All isolates were tested in an authentic peroxynitrite anti-oxidant assay. Of these compounds, hispaglabridin B ( 6 ), isoliquiritigenin ( 7 ), and paratocarpin B ( 9 ) were found to be the most potent anti-oxidant agents. Furthermore, isoliquiritigenin ( 7 ) was demonstrated to prevent the incidence of 1,2-dimethylhydrazine-induced colon and lung tumors in mice when administered at a dose of 300 mg/kg. Keywords: Glycyrrhiza glabra; licorice; Fabaceae; chalcones; neolignan lipid ester; mixture; phenolic derivatives; peroxynitrite; anti-oxidant activity; 1,2-dimethylhydrazine; colon and lung tumors