LIGNANS FROM THE ROOTS OF URTICA-DIOICA AND THEIR METABOLITES BIND TOHUMAN SEX-HORMONE BINDING GLOBULIN (SHBG)

Polar extracts of the stinging nettle (Urtico dioico L.) roots contain the lignans (+)-neoolivil, (-)-secoisolariciresinol, dehydrodiconifer yl alcohol, isolariciresinol, pinoresinol, and 3,4-divanillyltetrahydr ofuran. These compounds were either isolated from Urtica roots, OF Obt ained semisynthetically. Their affinity to human sex hormone binding g lobulin (SHBG) was tested in an in vitro assay. In addition, the main intestinal transformation products of plant lignans in humans, enterod iol and enterolactone, together with enterofuran were checked for thei r activity. All lignans except (-)-pinoresinol developed a binding aff inity to SHBG in the in vitro assay. The affinity of (-)-3,4-divanilly tetrahydrofuran was outstandingly high. These findings are discussed w ith respect to potential beneficial effects of plant lignans on benign prostatic hyperplasia (BPH).