Background:

IC50: Not available.

Equol is an isoflavan produced by intestinal bacteria in response to soy isoflavone intake in human. It shows a wide range of activities including antioxidant activity, anti-inflammation activity and anticancer activity. It is reported that Equol specifically binds to 5α-DHT and has a modest affinity for recombinant estrogen receptor ERβ, which may be responsible for most of Equol’s biological properties. [1]

In vitro: In vitro studies were conducted to measure both the binding affinity of Equol for 5alpha-dihydrotestosterone (5alpha-DHT) and the effects of Equol treatment in human prostate cancer (LNCap) cells. It was found that Equol bound to 5alpha-DHT with maximum and half maxim concentrations of 100 nM and 4.8 nM, respectively. In addition, Equol significantly offset the increases in PSA levels from LNCap cells. [1]

In vivo: An in vivo study was performed to investigate effects of equol on rat prostate weight and circulating levels of sex steroid hormones. 1.0 mg/kg of Equol was injected to Long-Evans rats fed with a low isoflavone diet for 25 days. Findings from this study suggested that Equol significantly decreased rat prostate weights and down-regulated serum levels of 5alpha-DHT. However, this agent did not alter levels of LH, testosterone and estradiol. [1]

Clinical trials: A clinical study on hypercholesterolemic patients demonstrated that, after 4 weeks’ dietary intervention with a soy isoflavone-containing food, brachial artery-mediated vasodilatation in equol-producers was notably higher when compared with that in equol-nonproducers. Similar differential effects between equol-producers and nonproducers were aslo reported in arterial stiffness from a study on postmenopausal women taking tibolone. [2]

参考文献:
[1]Lund TD, Blake C, Bu L, Hamaker AN, Lephart ED.  iEquol an isoflavonoid: potential for improved prostate health, in vitro and in vivo evidence. Reprod Biol Endocrin. 2011; 9(4): doi: 10.1186/1477-7827-9-4.
[2]Setchell DR and Clerici C.  Equol: Pharmacokinetics and biological actions. J Nutr. 2010 Jul; 140(7): 1363S–8S.