Aspidosperma quebracho–blanco (commonly called Quebracho) has traditionally been used as a stimulant, as aphrodisiac. It is now marketed as “herbal Viagra” as it may increase sex drive and as bodybuilding supplement for increasing muscle mass (via increased testosterone).
Why is Aspidosperma Quebracho in Testosterone Boosters?
In some countries bark extract of Aspidosperma quebracho-blanco, is used as a prescription drug to treat erectile dysfunction . A group of German rearchers  have shown that bark extract of Aspidosperma quebracho-blanco is a fairly potent alpha-2 andregenic receptor antagonist; however, exhibited pro-erectile effect was probably caused by yohimbine content. Yohimbine also seems to be the main active ingredient.
There is not enough researche available to know for sure how Aspidosperma quebracho-blanco extract works. It’s effects seem to be mostly related to effects of yohimbine such as weight loss and improved penile erection. There is no evidence that Aspidosperma quebracho-blanco increases testosterone levels.
Pharmacology of Aspidosperma Quebracho-blanco Extract
Besiders yohimbine other consituetns such as aspidospermine, quebrachamine and quebrachine  can be found in bark extract of Aspidosperma quebracho-blanco. Aspidospermine was reported to reduce blood pressure  and is also used to treat and relieve various form of dyspnoea and asthma  (either as citrate, suplhate or hydrocloride). Quebrachine is an alakloid that has been shown to posses similar mode of action as yohimbine as they are closely related . Quebrachamine, as well as aspidospermine were also reported to posses adrenergic blocking activities .
Evidence for any of the claimed effects of Aspidosperma quebracho-blanco extract are lacking.
Side Effects and Dosage
There is not enough scientific research to determine recommended dosage. Quebracho seems to be safe in small amounts, however, there isn’t enough information to know if quebracho is safe in larger amounts .
(Other common names: Quebracho Blanc, Quebracho Blanco, White Quebracho)
- Sperling, Herbert, et al. “An extract from the bark of Aspidosperma quebracho blanco binds to human penile α-adrenoceptors.” The Journal of urology 168.1 (2002): 160-163.
- Banerjee, J. N., and J. J. Lewis. “A note on the pharmacology of aspidospermine.” Journal of Pharmacy and Pharmacology 7.1 (1955): 46-49.
- Lotter, Angelique Natalia Cassandra. A Novel Method for the Synthesis of Indolo [2, 1-a] isoquinolines. Diss. 2006.
- Weinberg, S. J. “The pressor action of yohimbine and quebrachine.” Journal of Pharmacology and Experimental Therapeutics 47.1 (1933): 79-93.
- Deutsch, Harold F., et al. “Isolation and biological activity of aspidospermine and quebrachamine from an Aspidosperma tree source.” Journal of pharmaceutical and biomedical analysis 12.10 (1994): 1283-1287.
- WebMD.com “Quebracho” Retrieved 10. June 2014