3′-isoprenylgenistein: The Master Phyto-SERM


Since the dawn of man, humans have been aware that plants contained not only the micronutrients they needed to survive and live a healthy life, but also  a seemingly infinite amount of naturally occuring chemicals, many of which have unique properties and behaviors within the human body.

Modern science has termed these chemicals “phytonutrients”, defined as:

“a substance found in certain plants which is believed to be beneficial to human health”

You see, there are micronutrients and macronutrients, but there are also a seemingly unlimited amount of naturally occuring chemicals with an endless amount of potential applications.  We still have a long way to go towards understanding what Mother Nature truly has to offer us, but thanks to modern science, we’ve been able to not only identify useful plants, but actually identify and isolate the active components.


Phytoestrogens are unique molecules found in certain plants (these plants are considered “phytoestrogenic”) which resemble the chemical structure of Estrogen in the human body.  Because of the close structural similarities, phytoestrogens are capable of interacting with Estrogen receptors within the human body.  They can either be:

  • Estrogenic – the phytoestrogen interacts with Estrogen Receptors in such a way that enhanced Estrogenic signaling.
  • Anti-Estrogen – the phytoestrogen binds to the Estrogen Receptor, effectively blocking actual Estrogens from interacting with it.

Some Phytoestrogens decrease Estrogenic activity in places where it can be a problem (like breast tissue) and increase Estrogenic activity in places where it’s beneficial.  Such compounds are called Selective Estrogen Receptor Modulators, or SERMs.  You may have heard this term before because it is the term used to define certain anti-estrogenic compounds such as the perscription medication, Tamoxifen.

When they’re found in plants, however, they have a special name…


Phyto-SERMs are simply SERMs found in plants.  “Phyto” means plant.  Phyto-SERM.  It has a nice ring to it…and some of these Phyto-SERMs are quite powerful.

In fact, a recent study actually pitted two dozen Phyto-SERMS against Tamoxifen itself in order to determine just how effective these compounds were at combatting Estrogen.  The results revealed that many of these Phyto-SERMS indeed had anti-estrogenic activities, but one in particular was nearly as potent as Tamoxifen at combatting Estrogen…


The table below shows the anti-estrogenic activity of several Phyto-SERM compounds, relative to Tamoxifen and Raloxifene, two powerful perscription SERMs.

3’-isoprenylgenistein Estrogen

As you can see, compound 8 (3′-isoprenylgenistein) was by far the most potent.  In fact, in terms of anti-estrogenic activity, it was almost as potent as Tamoxifen.  This is pretty remarkable considering Tamoxifen is a synthetic perscription medication and 3′-isoprenylgenistein is simply a naturally occuring molecule found in the plant species, Flemingia macrophylla.

Interestingly, 3′-isoprenylgenistein (8) showed a more potent anti-estrogenic effect compared to genistein (5). This dual activity opens a new avenue for selecting and designing a perfect SERM

3′-isoprenylgenistein, and other Phyto-SERMs with similar anti-estrogenic activity (there are other plants which contain other Phyto-SERMs), offer an alternative to the often hard to source prescription SERMs.  While 3′-isoprenylgenistein may not be quite as anti-estrogenic as Tamoxifen, it’s certainly an effective addition to any PCT stack, especially when combined  with an Aromatase Inhibitor.

Prenylation: The Key To 3′-isoprenylgenistein

3′-isoprenylgenistein is the a prenylated version of genistein, a Phytoestrogen that doesn’t appear to be particularly potent in any regard.  This is because the structure of genistein makes it difficult for it to beind with Estrogen Receptors, but prenylation solves this issue.

Prenylation is the process by which a hydrophobic molecule is attached to a compound, making it more capable of binding to the receptor site.  3′-isoprenylgenistein is simply genistein with a prenyl group attached to the third (3) carbon atom.  This seemingly slight alteration makes 3′-isoprenylgenistein bind to the Estrogen Receptor with ease, blocking more estrogenic compounds from binding an eliciting Estrogenic effects. exists to educate the supplement community and seperate the science from the hype.

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