Naphthoquinone derivatives and lignans from the Paraguayan crude drug "tayï pytá" (Tabebuia heptaphylla, Bignoniaceae).

The Paraguayan crude drug "tayï pytá" is used to treat cancer, wounds and inflammation. It consist of the bark and trunkwood of Tabebuia heptaphylla (Bignoniaceae). A phytochemical study of the crude drug gave, in addition to previously described naphthoquinones and the known lignans cycloolivil and secoisolariciresinol, three new lapachenol (lapachonone)-, two naphthofuran-, a chromone and a naphthalene derivative. The structures were elucidated by means of high field NMR spectroscopy. The biological activity of the main compound lapachol and the related alpha-lapachone as well as the lignans cycloolivil and secoisolariciresinol can explain, at least in part, the effect atributed to the crude drug in Paraguayan folk medicine.