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Bioactive furonaphtoquinones from Tabebuia barbata (Bignoniaceae)
T Colman de Saizarbitoria1, J E Anderson, D Alfonso
1Facultad de Farmacia, Universidad Central de Venezuela, Caracas, Venezuela.
Acta Cientifica Venezolana
|January 1, 1997
Summary
Five naphthoquinones isolated from Tabebuia barbata bark exhibited significant cytotoxicity against cancer cells and inhibited mitochondrial electron transport. Brine shrimp lethality bioassay effectively identified these potential antitumor compounds.
Area of Science:
- Phytochemistry
- Pharmacology
- Natural Products Chemistry
Background:
- Tabebuia barbata, known as "palo de arco", is a plant indigenous to the upper Orinoco and Amazonas rivers.
- This species has not been previously investigated for its chemical constituents or biological activities.
Purpose of the Study:
- To isolate and identify bioactive compounds from the ethanol extract of Tabebuia barbata bark.
- To evaluate the cytotoxic and mitochondrial electron transport inhibitory activities of the isolated compounds.
Main Methods:
- Brine shrimp lethality-directed fractionation was employed.
- Extensive column chromatography, preparative TLC, and HPLC were used for separation.
- Spectral evidence (UV, IR, NMR, mass spectrometry) was used for structural identification.
Main Results:
- Five naphthoquinone compounds (lapachol, and four acetylnaphthofuranones) were isolated and identified.
- Compounds 2-5 demonstrated significant cytotoxicity against A-549 lung, MCF-7 breast, and HT-29 colon carcinoma cell lines.
- All isolated compounds (1-5) inhibited rat liver mitochondrial electron transport, with IC50 values ranging from 15 to 82.5 microM.
Conclusions:
- The study successfully isolated and characterized five naphthoquinones from Tabebuia barbata.
- The isolated compounds possess significant antitumor potential and can inhibit mitochondrial electron transport.
- Brine shrimp lethality assay is an effective tool for discovering potential anticancer agents from natural sources.