(S)-Equol

Equol (4',7-isoflavandiol) is an isoflavandiol estrogen metabolized from daidzein, a type of isoflavone found in soybeans and other plant sources, by bacterial flora in the intestines. While endogenous estrogenic hormones such as estradiol are steroids, equol is a nonsteroidal estrogen. However, only about 30-50% of people have intestinal bacteria that make equol. Equol can exist in two enantiomeric forms, (S)-equol and (R)-equol. (S)-Equol preferentially binds estrogen receptor beta. Equol (4',7-isoflavandiol) is an isoflavandiol estrogen metabolized from daidzein, a type of isoflavone found in soybeans and other plant sources, by bacterial flora in the intestines. While endogenous estrogenic hormones such as estradiol are steroids, equol is a nonsteroidal estrogen. However, only about 30-50% of people have intestinal bacteria that make equol. Equol can exist in two enantiomeric forms, (S)-equol and (R)-equol. (S)-Equol preferentially binds estrogen receptor beta. (S)-Equol was first isolated from horse urine in 1932, and the name was suggested by this equine connection. Since then, equol has been found in the urine or plasma of many other animal species, although these animals have significant differences in their effectiveness in metabolizing the soy isoflavone daidzein into equol. In 1980, scientists reported the discovery of equol in humans. The ability of (S)-equol to play a role in the treatment of estrogen- or androgen-mediated diseases or disorders was first proposed in 1984. Equol is a compound that can exist in two mirror image forms known as the enantiomers, (S)-equol and (R)-equol. However, only (S)-equol is produced in humans and animals with the ability to produce equol after soy isoflavone consumption. (S)-Equol is not of plant origin. It is a metabolite of the soy isoflavone daidzein. (S)-equol thus is characterized as an isoflavan. In contrast, R-equol is not made in humans, but can be chemically synthesized, such as in the laboratory. The molecular and physical structure of (S)-equol is similar to that of the hormone estradiol. Not all humans can produce (S)-equol after soy consumption. The ability to do so depends on having certain strains of bacteria living within the intestine. Twenty-one different strains of intestinal bacteria cultured from humans have the ability to transform daidzein into (S)-equol or a related intermediate compound. Several studies indicate that only 25 to 30 percent of the adult population of Western countries produces (S)-equol after eating soy foods containing isoflavones, significantly lower than the reported 50 to 60 percent frequency of equol-producers in adults from Japan, Korea, or China. Vegetarians are more capable of transforming daidzein in this substance too. In research studies, the ability of a person to produce (S)-equol is determined with a standardized test in which the person, who has not had antibiotics for at least a month prior to testing, drinks two 240 milliliter glasses of soy milk or eats a soy food equivalent for three days followed by measurement of (S)-equol concentrations in their urine on the test's fourth day. Seaweed and dairy consumption enhances the production of equol. Under the code name AUS-131, (S)-equol is under development for the treatment of menopausal symptoms such as hot flashes and benign prostatic hyperplasia. While many more bacteria are involved in the related intermediate process of (S)-equol production, such as conversion of daidzin to daidzein, or genistein to 5-Hydroxy-equol, the bacteria that can produce a complete conversion of daidzein to (S)-equol, are the following: However, the Bifidobacterium conversion has only been claimed once by Tsangalis et al. 2002, and not reproduced since. Mixed cultures such as Lactobacillus sp. Niu-O16 and Eggerthella sp. Julong 732 can also produce (S)-equol. Some equol producing bacteria, as implied by their nomenclature, are Adlercreutzia equolifaciens, Slackia equolifaciens and Slackia isoflavoniconvertens. Eqoul as skin health improving and anti-aging substance The topical effect of Equol as anti-aging and skin health improving substance was shown in different studies. Equol can occur as different isomeres: R-equol, S-equol and RS-eqoul. Each of these forms has different characters, bioavaibilities and molecular effects. As an antioxidative operating substance, equol can decrease the aging process by reducing ROS events. Additionally, the phytoestrogenic properties influence the skin health positively.