Although a constituent of chaparral has some anticancer qualities in vitro, there is no reliable clinical evidence of benefit. Chaparral is hepatotoxic and should not be used internally.
[LFODPKM ] Letter Key
Latin Name
Larrea tridentata (Sessé & Moc. ex DC.) Coville
Family
Zygophyllaceae
Other Common Names
Greasewood, creosote bush, hediondilla, gobernadora
Description
- A small woody, evergreen desert shrub with thorny stems and fleshy leaves that thrives in poor, sandy soil.
- It is common in the southwestern United States and Mexico.
- The plant has a pungent, acrid odor.
Part Used
Leaf
Known Active Constituents
- The lignan nordihydroguaiaretic acid (NDGA) constitutes 5% to 10% of the dry weight of leaves.
- Major secondary components are waxes, volatile compounds, saponins, and phenolics (the latter account for up to 91% of extractable dry weight). Phenolic compounds include flavonoid aglycones and glycosides, NDGA, and related lignans (including secoisolariciresinol, enterolactone, enterodiol, matairesinol, guaiaretic acid, dihydroguaiaretic acid, guaiaretic acid diquinone, and didehydrolarreatricin) (1).
Mechanism/Pharmacokinetics
- NDGA has antioxidant effects and inhibits cyclooxygenase and lipoxygenase pathways of arachidonic acid metabolism (2).
- Some components of chaparral have estrogenic and antiimplantation effects (1).
- NDGA competes with estradiol for binding to
-fetoprotein and demonstrates estrogenic effects in an assay using pS2 expression (an estrogen-responsive protein in ER + MCF breast cancer cells) (3).
[Outline]
[CAO ] Letter Key
Clinical Trials
- Psoriasis
- In a trial of four patients with stable plaque psoriasis, NDGA was tested in concentrations of 0.5%, 1.0%, 2.0%, and 3.0% w/v. All concentrations were tested in all patients, using a grid system on selected plaque. Betamethasone 17-valerate 0.025% ointment was used as an active control. Each treatment was applied daily for 14 days (with occlusion); patients were examined and the area photographed each day. Only the steroid cream squares appeared normal after 10 days; other treated areas showed no change other than reduction in scaling, attributable to occlusion (4).
- Cancer
- There is a case report of regression of rapidly growing recurrent malignant melanoma (previously excised three times) of the cheek in an 85-year-old man who, after refusing further medical treatment, began drinking 2 to 3 cups daily of chaparral tea; 10 months later the lesion had shrunk from 3 to 4 cm to 2 to 3 mm, satellite lesions had disappeared, a previous large, tender mass in the right inframandibular area had disappeared, and the patient had gained 25 pounds (5).
- On the basis of the previous case and some experimental data, the National Cancer Institute (NCI) sponsored a yearlong clinical trial of NDGA in patients with advanced malignancy; some patients drank chaparral tea and others received pure NDGA (250 to 3,000 mg/day) (6). Of 45 evaluable outcomes, four remissions were reported (apparently including the malignant melanoma patient mentioned previously). The other remissions were another patient with melanoma (3-month remission), a patient with testicular choriocarcinoma metastasized to the lung (remission of 2 months), and a patient with lymphosarcoma (regression lasted 10 days). None of these "remissions" was lasting. Apparently this report, published in the Rocky Mountain Medical Journal (7), lacks relevant clinical detail (6).
Animal/In Vitro
- Cancer
- NDGA and chaparral extracts have had mixed (predominately negative) effects in various animal tumor models (6).
- Renal effects
- NDGA has been used to induce renal cystic disease in rats (2). In mice, NDGA markedly reduces both toxic and carcinogenic effects of the renal carcinogen ferric-nitrilotriacetate (8).
- Immunosuppression
- In an in vivo model of allograft rejection in mice, NDGA had a beneficial effect (compared with a vehicle control) in preventing infiltration and subsequent cytotoxicity of sensitized effector cells without compromising basic cell functions (9).
Other Claimed Benefits/Actions
- Kidney problems
- Colds
- Arthritis
- Tuberculosis
- Chickenpox
- Gastrointestinal complaints
- Rheumatism (topical)
- Cuts, sores, bruises, burns (topical)
- Contraception
- Weight loss
- Liver tonic
[Outline]
Q: Wasn’t NDGA used in foods?
A: Yes. Up until 1967 (when more effective antioxidants were introduced), NDGA was used in the United States as a food preservative in lard, oils, candies, baking mixes, frozen foods, and so forth at levels up to 0.02% (5).
Q: Why aren’t there more cases of liver injury reported?
A: As with other herb or drug hepatotoxins, there is varying susceptibility to hepatotoxic effects.
Q: Where does the Spanish name for this plant (gobernadora means governess) come from?
A: The plant crowds out other plants. Apparently the plant concentrates salts from the soil and falling leaves deposit these salts on the surface of the soil, creating an inhospitable environment for other plants.
Q: Are some preparations of chaparral more toxic than others?
A: Teas may be much safer than tablets, capsules, or alcohol extracts. Most (although not all) cases of chaparral toxicity have been linked to capsules or tablets, which may be much more toxic than teas simply because eating the leaves provides a larger dose of NDGA and other compounds; a hot water infusion is not very efficient at extracting these compounds. High-pressure liquid chromatography (HPLC) chromatograms of a methanolic extract of chaparral compared with chaparral tea found that the methanolic extract extracted much more NDGA (and other lignans) than the aqueous extract (1). Alcohol extracts of chaparral, tablets, and capsules are currently available; their use should be strongly discouraged. Chaparral tea is most likely less toxic but may not be completely benign. Given the lack of evidence of any benefit, all internal uses of chaparral should be discouraged. There is no evidence that external application is harmful (or, for that matter, beneficial).