Pau d'arco is an herb taken from the bark of the Tabebuia Impetiginosa or Tabebuia Avellanedae tree, which grows mainly in Central and South America. It has a long history in herbal medicine around the world. The chemical constituents and active ingredients of pau d'arco include a large percentage of chemicals known as quinoids, and a small quantity of benzenoids and flavonoids. The quinoids--chiefly, anthraquinones, furanonaphthoquinones, lapachones, and naphthoquinones--have shown the most documented biological activity and are seen to be the center of the plant's efficacy as an herbal remedy. In South American herbal medicine, pau d'arco is considered to be an astringent, anti-inflammatory, antibacterial, antifungal, and laxative. The herb has been used to treat ulcers, syphilis, urinary tract infections, psoriasis, gastrointestinal problems, candidiasis, cancer, diabetes, prostatitis, constipation, and allergies. It is also used in Brazilian herbal medicine for many conditions including leukemia, ulcers, diabetes, rheumatism, arthritis, dysentery, stomatitis, and boils. In North American herbal medicine, pau d'arco may be suggested as an herbal treatment for fevers, infections, colds, flu, syphilis, cancer, respiratory problems, skin ulcerations, boils, dysentery, gastrointestinal problems of all kinds, arthritis, prostatitis, and circulation disturbances. Pau d'arco also is sometimes employed in herbal medicine systems in the United States for patients with lupus, diabetes, ulcers, leukemia, allergies, liver disease, Hodgkin's disease, osteomyelitis, Parkinson's disease, and psoriasis, and is a popular remedy for candida and yeast infections. Studies done in the 1960s showed plant extracts of the heartwood and bark demonstrated marked antitumorous effects in animals, which drew the interest of the National Cancer Institute (NCI).
