Eurycomanone, the major quassinoid in Eurycoma longifolia root extract increases spermatogenesis by inhibiting the activity of phosphodiesterase and aromatase in steroidogenesis.
Level 5 - mechanism / opinion, no new human data
In vitro cell culture and computational molecular docking study (bench mechanistic research)
PubMed 23810842 · doi:10.1016/j.jep.2013.06.023
What was done
Rat testicular Leydig cell-rich interstitial cells (1.0 × 10^5 cells) were isolated and incubated for 2 hours with eurycomanone (the primary quassinoid in *Eurycoma longifolia*) alone or alongside standard steroidogenesis inhibitors (IBMX, aminoglutethimide, ketoconazole, nifedipine, tamoxifen, and formestane). Testosterone and estrogen concentrations were measured by ELISA. Computational molecular docking was performed to assess eurycomanone binding affinities to target steroidogenic enzymes.
What was found
Eurycomanone significantly increased testosterone production dose-dependently at 0.1, 1.0, and 10.0 μM (P < 0.05). Co-administration with the phosphodiesterase inhibitor IBMX yielded no significant increase over either compound alone at 0.1 and 1.0 μM, but showed an additive effect at higher concentrations. Eurycomanone did not reverse inhibition by aminoglutethimide, ketoconazole, or nifedipine, and did not respond to estrogen receptor blockade by tamoxifen. However, it enhanced formestane-induced aromatase inhibition to decrease estrogen production, with molecular docking showing eurycomanone and formestane shared similar binding orientations and free energy values on aromatase.
Why it matters
These findings identify specific molecular mechanisms—notably aromatase inhibition and possible phosphodiesterase modulation in Leydig cells—underlying the testosterone-enhancing properties attributed to Tongkat Ali root extract.
Limits
The study was entirely in vitro using rat cells and in silico modeling; findings cannot establish in vivo efficacy, optimal dosing, or safety in humans. Exact baseline and post-treatment hormone concentrations and donor animal sample sizes were not reported in the abstract.
Cited by
- partial Tongkat Ali suppresses SHBG and upregulates steroidogenic acute regulatory protein (StAR) to transport cholesterol into mitochondria for testosterone production.