Bottom Line: Pau d’arco has antibacterial and anticancer activities in laboratory studies, but these effects have not been shown in humans.
Pau d’arco, a tree native to South America, has been used in traditional medicine for a wide range of ailments. In laboratory studies, compounds extracted from pau d’arco showed antibacterial, antifungal, anti-inflammatory, antidepressant, and anticancer properties. However, the safety and effectiveness of these compounds has not been confirmed in humans.
You are taking anticoagulants: In theory, pau d’arco may increase bleeding risk with these drugs.
You are taking vitamin K: Lapachol in pau d’arco may inhibit the activity of this supplement.
You are pregnant or trying to conceive: There have been reproductive toxicities in animal models.
Pau d’arco is a tree native to South America. Preparations derived from the bark have been traditionally used to treat bacterial, fungal, or viral infections, and cancer. Quinones have been identified as the main active constituents (1)(2)(3)(4).
In vitro and in vivo studies of compounds isolated from pau d’arco demonstrate antibacterial (5)(6)(7)(8), antifungal (9), antipsoriatic (10), immunomodulatory (11)(12), anti-inflammatory (13)(14), antidepressant (15), anticoagulant (16), anticancer (1)(2)(3)(4)(17), and antimetastatic (4) properties. Taheebo extract from the inner bark of pau d’arco selectively inhibits growth of ER positive breast cancer cells (18), but human studies are needed to validate these effects.
In a small single-arm study, the isolated naphthoquinone lapachol failed to show any effects on patients with non-leukemic tumors or chronic myelocytic leukemia (19).
The anticoagulant effect of lapachol is due to the inhibition of vitamin K epoxide and quinone reductases (16).
The anticancer activity of beta-lapachone, an isolated quinone compound, may be due to downregulation of cyclooxygenase (COX-2) and telomerase activities (1). Beta-lapachone also induces apoptosis in cancer cells via mitochondrial-signaling (2) or by activating caspases (5)(11)(22). The antimetastatic activity of beta-lapachone occurs by inducing Egr-1, known to suppress metastasis, thereby decreasing the invasive ability of cancer cells (4).
In animal studies
Anemia: With large, chronic dosing of lapachol (23). Reproductive toxicity: Short-term administration of lapachol caused significant reduction in seminal vesicle weight (24). Lapachol also has an abortifacient effect (25). Clastogenic effects: Oral administration of lapachol caused chromosomal abnormalities (26).