Tabebuia avellanedae and its constituents as antagonists of human derived tumour cells

Tabebuia avellanedae (Bignoniaceae) (TA), which is native to South America, from Brazil to northern Argentina, is well known in traditional folk medicine for the treatment of various diseases. Previously, we reported that 5-hydorxy-2-hydroxyethyl)-naphtho[2,3-b]-furan-4,9-dione (NFD), one of the anti-tumour promoting constituents of this plant, inhibits TPA-induced in an in vitro assay and thereby acts as a chemopreventive agents. These data suggest that the extract of TA and its constituents might be a functional material for chemoprevention similar to fruits and vegetables. These facts promoted us to examine the chemopreventive effects of TA since the inner bark of this plant which is produced in Barazil is distributed in Asia as a herbal tea.

In our continuing research for potent and selective cytotoxic anti-tumour agents we have evaluated the cytotoxic effect of the extract and some of its constituents against a panel of human tumour cell lines. The dried freeze powder of TA extract showed lower activity on various tumour cells while one of its metabolites, a naphthoquinone derivative and some others showed increased cytotoxic activity. The presence of these active compounds in TA extract also validates the anti-tumour activity of this species. Further chemical and biological studies are in course for the characterization of these compounds.