EGCG is a phytoestrogen (plant estrogen) which has weak estrogen effects. More importantly, in neurons it binds estrogen beta receptors (ERβ) and this, in turn leads to inhibition of PI3K, mTOR, and ERK1/2, all of which are known to be overactive in Fragile X. The mouse studies will help to identify biomarkers of efficacy based on the activity of these pathways.

The trial includes 40 patients, ages 18-30, and was conducted in Barcelona, Spain.

We here propose that rare diseases leading to intellectual disability, such as Fragile X syndrome, where alterations in synaptic plasticity are involved, may benefit from treatments targeting Estrogen Receptors beta (ER-ß). Estrogens can act as neuroprotective agents, promoting synaptic plasticity and neurite outgrowth, and health benefits derived from flavonoids, phytoestrogens of natural origin are partially explained by their interaction with membrane ER. Selective ER-ß flavonoids are thus good candidates for their therapeutic evaluation in intellectual disabilities.

Our preliminary results suggest that the flavonol epigallocatechin gallate (EGCG), the isoflavone dadzein and the flavone apigenin could be good candidates for cognitive enhancement therapy in FXS. EGCG also targets central intracellular transduction signals (EGCG is an ATP-inhibitor of PI3K, and mTOR and ERK1/2) altered in FXS and improves memory recognition in a FXS animal model.