The Bolivian sunflower, or Tithonia diversifolia, is the Mexican sunflower's giant relative, reaching heights as great as 15 ft (5 m) and stretching as far as 12 ft (3.6 m) wide. While popular as a fast growing ornamental in regions where it can be grown, Tithonia diversifolia was once one of the medicinal plants used by the indigenous peoples of the Americas. Historically, the plant has been used in Mexico as a treatment for bone fractures, bruises and sprains. After its introduction to Taiwan and Southern China, the plant was incorporated into Chinese medicine, where it is still used to improve liver function, treat hepatitis and jaundice, help with night sweats, reduce water retention, lower blood pressure, fight athlete's foot, and combat cystitis. The United States Food and Drug Administration, however, has not yet judged whether Tithonia diversifolia is an effective treatment for these or other medical conditions.
Some research has indicated that Tithonia diversifolia may in fact have some genuine medical applications. One study found that an alcoholic extract of the dried leaves of the plant at doses between 50 and 200 mg per kilogram of body weight demonstrated diuretic, anti-inflammatory and pain relieving effects in rats. Higher doses of the extract produced a linear increase in the herb's pain relieving and anti-inflammatory properties. The authors were not able to conclusively determine which chemical or chemicals were responsible for these effects.
Tithonia diversifolia's rich variety of sesquiterpene lactones and novel sesquiterpenoid phytochemicals were the subject of another study. The authors found that an extraction of a number of these showed promise in the treatment of cancer. Isolates of two of the sesquiterpene lactones demonstrated statistically significant reduction in the proliferation of colon cancer cells in vitro, while another significantly inhibited lesion formation in breast cancer in mice. The novel sesquiterpenoid was found to induce HL-69 cellular differentiation. Potential pharmacological applications for these chemicals are not limited to the treatment of cancer, though, as several of the same chemicals have also been shown to inhibit the parasite responsible for causing malaria.