From Ergo Log
They've done it. Researchers at the Universiti Sains Malaysia have worked out how extracts of Eurycoma longifolia – a plant you probably know by the name Tongkat Ali – boost testosterone levels. The extracts contain the compounds eurycomanone and 13-alpha (21) epoxy-eurycomanone, and these boost the production of the hormones LH and FSH.
The researchers used methanol to make an extract of Eurycoma longifolia and further purified it, separating it into to four fractions. The researchers discovered that one of the fractions increased the weight of the testes of the lab animals more than the others. This was the extract that consisted of 32 percent quassinoids. The two most important of these were eurycomanone and 13-alpha (21) epoxy-eurycomanone.
A dose of 25 mg per kg bodyweight of the active Eurycoma longifolia extract caused a considerable rise in rats' testosterone levels over a period of 52 days. This increase was accompanied by a rise in LH and FSH levels, and a decrease in the amount of estradiol in the rats' blood.
When the researchers gave their lab rats the Eurycoma longifolia quassinoids separately, both eurycomanone and 13-alpha (21) epoxy eurycomanone boosted the rats' testosterone levels.
The results of this study are not completely unexpected. In 2011 researchers from the same university published the results of a study in which they showed that eurycomanone had an anti-oestrogen effect comparable to that of tamoxifen, the active ingredient in Nolvadex. [Planta Med. 2011 Jan;77(2):128-32.]
The researchers were funded by the Malaysian Ministry of Science, Technology and Innovation and their university – and not by the supplements industry.
J Ethnopharmacol. 2013 Feb 13;145(3):706-14.