Lapachol and beta-lapachone, isolated from the inner bark of trees used to produce Pau d’arco, are thought to be the active constituents that are responsible for its pharmacological activities ⁽²⁰⁾. Beta-lapachone downregulates cyclooxygenase (COX-2) and telomerase activities ⁽¹⁾. It also induces apoptosis in cancer cells via mitochondrial signaling ⁽²⁾ or by activating caspases ^{(5) (9) (2)}. The antimetastatic activity of beta-lapachone occurs by inducing Egr-1, known to suppress metastasis, thereby decreasing the invasive ability of cancer cells ⁽⁴⁾. A water extract of Taheebo showed anti-proliferative effects on hormone-sensitive MCF7 breast cancer cells by modulating gene expression, thereby interfering with cell cycle progression. At high doses, it also has anti-estrogenic effects through the inhibition of estrogen receptor signaling ⁽¹⁶⁾. A methanolic extract of taheebo inhibited cell proliferation through the extracelluar signal regulated kinase (ERK1/2) mitogen activated protein kinase (MAPK) pathway ⁽¹⁰⁾.

Lapachol’s anticoagulant activity is due to the inhibition of vitamin K epoxide and quinone reductases, an action similar to that of warfarin ⁽¹⁴⁾.

However, it is important to note that the clinical effects of Pau d’arco are difficult to predict because they are influenced by several factors including variation in plant species or plant parts, extraction methods, bioavailability of the active compounds, dosages and routes of administration.