Sigmoidins J and K, two new prenylated isoflavonoids from Erythrina sigmoidea

In addition to the two known compounds neotautenol [2] and erythrinassinate B [4], two new compounds, an isoflavanone named sigmoidin J [1] and a coumestan derivative named sigmoidin K [3], have been isolated and characterized from the root bark of the Cameroonian medicinal plant Erythrina sigmoidea. Their structures have been established as 7, 4'-dihydroxy-2',5'-dimethoxy-6'(gamma, gamma-dimethylally)isoflavanone [1] and 3,9-dihydroxy-2,10-(gamma, gamma dimethylallyl) coumestan [3], respectively, by spectroscopic techniques and from chemical evidence.