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.
