has role independent continuant antioxidant flavonols glycosyloxyflavone bone density conservation agent EC 3.1.4.35 (3',5'-cyclic-GMP phosphodiesterase) inhibitor phytoestrogen icariin CHEBI:78420 A member of the class of flavonols that is kaempferol which is substituted at position 8 by a 3-methylbut-2-en-1-yl group and in which the hydroxy groups at positions 3, 4', and 7 have been converted to the corresponding 6-deoxy-α-<small>L</small>-mannopyranoside, methyl ether, and β-D-glucopyranoside, respectively. A phoshphodiesterase-5 inhibitor, it is obtained from several species of plants in the genus <em>Epimedium</em> and is thought to be the main active ingredient of the Chinese herbal medicine Herba Epimedii (yinyanghuo).