From Ergo Log
Supplements manufacturers sell Pau d'arco an extract made from the bark of the South American tree Tabebuia avellandae as an immune booster, but according to researchers at the Strang Cancer Prevention Center in New York, Pau d'arco also has an antioestrogenic effect. Could natural bodybuilders combine Pau d'arco with pomegranate?
South American Indians have been using Pau d'arco, often as a tea, for hundreds of years against infectious diseases. The extract contains naphthaquinones such as lapachol [structural formula to the right] and anthroquinones, which can have a toxic effect. If you give heavy doses of lapachol to pregnant lab animals, their embryos die. [Braz J Biol. 2001 Feb;61(1):171-4.]
Molecular oncologists have been examining Pau d'arco's potential as a medicine against cancer. The researchers at the Strang Cancer Prevention Center exposed MCF-7 breast cancer cells, which grow faster the more estradiol they get, to a water-based extract of Pau darco. The stronger the extract, the more deadly it was for the cancer cells.
When the researchers examined the activity of important genes in the cells, they saw how Pau d'arco inhibited the cancer cells: it boosted the activity of the gene for the enzyme CYP1A1 by a factor of 19.8 [the figure below is logarithmic, not linear]. The activity of the gene for CYP1B1 increased by a factor of 7.9.
CYP1A1 is, as far as estradiol is concerned, a 'good' enzyme. It converts estradiol into the harmless 2-hydroxy-estradiol. CYP1B1 is a 'less good' enzyme, and converts estradiol into 4-hydroxy-estradiol. 4-hydroxy-estradiol is also less active than estradiol, but it is an oncological worry, as it can attach itself to the DNA, causing damage and turning a healthy cell into a cancer cell.
If you still smoke, you're better off not using Pau d'arco: smokers with extra active CYP1A1 genes develop cancer more frequently than other smokers.
Substances such as grapeseed extract and pomegranate extract inhibit aromatase, the enzyme that converts testosterone into estradiol. When combined with a CYP1A1-booster such as Pau d'arco, these substances might just have an unexpectedly powerful antioestrogenic effect.
You can read more about naturally occurring substances that have real or suspected antioestrogenic effects here.
Mol Nutr Food Res. 2014 Jun 27. doi: 10.1002/mnfr.201300806. [Epub ahead of print].