Taheebo

Scientific Name(s): Tabebuia avellanedae Lorentz ex Griseb. Family: Bignoniaceae (trumpet creepers). This species is synonymous with T. impetiginosa Mart. ex DC., T. heptaphylla Vell. Toledo, and T. ipé Mart. ex Schum. The distinct related species Tecoma curialis Solhanha da Gama is sometimes marketed under the same names.

Common Name(s): Taheebo , Pau d'Arco , Lapacho morado , Lapacho colorado , Ipé Roxo

Uses

Taheebo is widely used in alternative cancer therapy without sufficient scientific proof. It may be more useful in antifungal applications, although no clinical trials have been conducted for any indication.

Dosing

Taheebo bark has been used as an alternative cancer treatment; however, there are no clinical studies to support a specific dose.

Contraindications

Do not use taheebo with anticoagulants.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

Do not use taheebo with anticoagulants.

Adverse Reactions

There are no reported serious side effects.

Toxicology

No toxicology has been reported for either the bark extract or its main constituents.

Botany

Tabebuia is a large genus of tropical trees that grows worldwide. According to one source, the correct name for the source species is T. impetiginosa ; 1 however, the majority of biological and chemical studies of the plant refer to T. avellaneda . The commercial product is derived from the inner bark. The tree grows widely throughout tropical South America, including Brazil, Paraguay, and northern Argentina. It has a hard, durable, and attractive wood that is extremely resistant to insect and fungal attack.

History

Taheebo has been promoted for many years as an anticancer herb, and lay reports have claimed efficacy in a variety of cancers. 2 Antifungal and antibiotic properties are also claimed in promotional literature, with both topical and oral dosing for candidiasis.

Chemistry

The naphthoquinone lapachol was isolated from the heartwood of the species in 1882, 3 and other related naphthoquinones (lapachones) have also been found in the wood. 4 Their structures were elucidated by Hooker 5 and others 6 and lapachol was synthesized by Fieser in 1927. 7 The inner bark has a distinct group of furanonaphthoquinones not found in the wood, 8 , 9 , 10 and these compounds are more likely to be responsible for the bioactivity observed in commercial samples of taheebo than lapachol and lapachones. 11 , 12 Analysis of commercial samples has found only trace amounts of lapachol and lapachones. 8 HPLC methods have been published for the analysis of taheebo bark 13 and wood. 14 The furanonaphthoquinones have been produced in good yield in callus and cell suspension cultures of T. avellanedae . 15 They are found in a number of species of Tabebuia and related Bignoniaceae. 16 , 17 , 18

Other constituents of taheebo bark include 3 iridoid glycosides 19 and a number of simple benzoic acid derivatives. 9 A series of anthraquinones was also isolated from the wood. 20

Uses and Pharmacology

Animal data

Lapachol was extensively evaluated as an anticancer agent by the US National Cancer Institute and the Pfizer Co. in the 1960s. 21 , 22 It showed reproducible activity in mouse cancer models. 22

Clinical data

While oral absorption in humans was relatively poor, peak blood levels of 14 to 31 mcg/ml were attained with doses of 30 to 50 mg/kg. 21 Extensive modifications of the lapachol structure have been performed in pursuit of better antitumor activity, 23 in the search for antimalarial drugs, 24 and for antipsoriatic drugs. 25 Lapachol has also been reported to have modest antifungal and antibacterial activity, 26 as well as anti-inflammatory activity 27 and weak estrogenic action. 28

β-lapachone has been found to be active in tumor models. 29 It inhibits both murine leukemia virus reverse transcriptase and DNA polymerase-α, but not DNA polymerase-β and several other related enzymes. 30

While having apparent potential for drug development, the biological activity of lapachol and β-lapachone is not relevant to the use of taheebo bark, because the bark contains little of these constituents. Instead, the furanonaphthoquinones are the important constituents, having cytotoxic, 16 , 17 antifungal, antibacterial, 11 , 18 and rather potent immunomodulatory activity. 12 Stimulation of host response to cancer cells or microbial infection may be responsible, at least in part, for the activity of the bark extract in vivo.

Despite the promising activity shown by the furanonaphthoquinone constituents, there do not appear to be clinical studies to support the use of taheebo for any of the indications mentioned.

Dosage

Taheebo bark has been used as an alternative cancer treatment; however, there are no clinical studies to support a specific dose.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

Do not use taheebo with anticoagulants.

Adverse Reactions

No data.

Toxicology

The toxicology of lapachol was studied in detail by Morrison et al., 31 who found hemolytic anemia to be the principle limiting toxicity in dogs, monkeys, rats, and mice. Human toxicity because of lapachol was seen at doses more than 1.5 g/day, with an elevated prothrombin time that was reversed by administration of vitamin K. 21 Because lapachol is not a major constituent of taheebo bark, these studies are not entirely relevant to the commercial product.

Bibliography

1. Woodson R, et al. Flora of Panama: IX. Family 172: Bignoniaceae. Ann Missouri Bot Gard 1973;60:45.
2. Hartwell J. Plants used against cancer. A survey. Lloydia 1968;31:71.
3. Paterno E. Ricerche sull'acido lapico. Gazz Chim Ital 1882;12:337.
4. Gonçalves de Lima O, et al. Antibiotic substances in higher plants. XX. Antimicrobial activity of some derivatives of lapachol as compared with xyloidone, a new natural o-naphthoquinone isolated from extracts of heartwood of Tabebuia avellanedae . Rev Inst Antibiot, Univ Fed Pernambuco, Recife 1962;4:3.
5. Hooker S. Constitution of lapachol and its derivatives. The structure of the amylene chain. J Chem Soc 1896;69:1356.
6. Casinovi C, et al. Quinones from Tabebuia avellanedae . Ann Chim (Italy) 1962;52:1184.
7. Fieser L. Alkylation of hydroxynaphthoquinone. A synthesis of lapachol. J Amer Chem Soc 1927;49:857.
8. Girard M, et al. Naphthoquinone constituents of Tabebuia spp. J Nat Prod 1988;51:1023.
9. Wagner H, et al. Structure determination of new isomeric naphtho[2,3b]furan-4,9-diones from Tabebuia avellanedae by the selective-INEPT technique. Helv Chim Acta 1989;72:659.
10. Fujimoto Y, et al. Studies on the structure and stereochemistry of cytotoxic furanonaphthoquinones from Tabebuia impetiginosa : 5- and 8-hydroxy-2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-diones. J Chem Soc Perkin Trans I 1991;2323.
11. Binutu O, et al. Antibacterial and antifungal compounds from Kigelia pinnata . Planta Med 1996;62:352.
12. Kreher B, et al. New furanonaphthoquinones and other constituents of Tabebuia avellanedae and their immunomodulating activities in vitro. Planta Med 1988;54:562.
13. Steinert J, et al. HPLC separation and determination of naphtho[2,3-b]furan-4,9-diones and related compounds in extracts of Tabebuia avellanedae (Bignoniaceae). J Chromatogr A 1995;693:281.
14. Steinert J, et al. High-performance liquid chromatographic separation of some naturally occurring naphthoquinones and anthraquinones. J Chromatogr A 1996;723:206.
15. Ueda S, et al. Production of anti-tumour-promoting furanonaphthoquinones in Tabebuia avellanedae cell cultures. Phytochemistry 1994;36:323.
16. Diaz F, et al. Furanonaphthoquinones from Tabebuia ochracea ssp. neochrysanta . J Nat Prod 1996;59:423.
17. Rao M, et al. Plant anticancer agents. XII. Isolation and structure elucidation of new cytotoxic quinones from Tabebuia cassinoides . J Nat Prod 1982;45:600.
18. Gafner S, et al. Antifungal and antibacterial naphthoquinones from Newbouldia laevis roots. Phytochemistry 1996;42:1315.
19. Nakano K, et al. Iridoids from Tabebuia avellanedae . Phytochemistry 1993;32:371.
20. Burnett A, et al. Naturally occurring quinones. Part X. The quinonoid constituents of Tabebuia avellenedae (Bignoniaceae). J Chem Soc (C) 1967;2100.
21. Block J, et al. Early clinical studies with lapachol (NSC-11905). Cancer Chemother Repts 1974;4:27.
22. Rao K, et al. Recognition and evaluation of lapachol as an antitumor agent. Cancer Res 1968;28:1952.
23. Linardi M, et al. A lapachol derivative active against mouse lymphocytic leukemia P-388. J Med Chem 1975;18:1159.
24. Fieser L, et al. Naphthoquinone antimalarials: general survey. J Amer Chem Soc 1948;70:3151.
25. Müller K, et al. Potential antipsoriatic agents: Lapacho compounds as potent inhibitors of HaCaT cell growth. J Nat Prod 1999;62:1134.
26. Guirard P, et al. Comparison of antibacterial and antifungal activities of lapachol and β-lapachone. Planta Med 1994;60:373.
27. De Almeida E, et al. Antiinflammatory actions of lapachol. J Ethnopharmacol 1990;29:239.
28. Sareen V, et al. Evaluation of oestrogenicity and pregnancy interceptory efficacy of lapachol. Phytotherapy Res 1995;9:139.
29. Schaffner-Sabba K, et al. β-Lapachone: Synthesis of derivatives and activities in tumor models. J Med Chem 1984;27:990.
30. Schürch A, et al. β-Lapachone, an inhibitor of oncornovirus reverse transcriptase and eukaryotic DNA polymerase-α. Eur J Biochem 1978;84:197.
31. Morrison R, et al. Oral toxicology studies with lapachol. Toxicol Appl Pharmacol 1970;17:1.

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