Breast isoflavones

WS-7528 [132147-69-4][VI] a nonsteroidal estrogen, is an isoflavone which has been isolated from Streptomjces sp. No. 7528 and is an estrogen agonist. It inhibits [3ff]-estradiol binding to its receptor in rat uterine cytosol at an inhibitor for 50% of the rats tested (IC q) concentration of 5.7 nM. It also induces the growth of estrogen-dependent human breast cancer cell line MCE-7 (7). 

FRANKE A A, CUSTER L J and TANAKA Y (1998) Isoflavones in human breast milk and other biological fluids. Am J Clin Nutr. 68 (6 Suppl) 1466S-73S. 

Although there is some controversy about how much soy must be consumed to benefit from its phytoestrogen effect, it is beheved that two servings per day will modestly reduce menopausal symptoms and the risk of breast cancer. More than three servings may reduce cholesterol. Although it has yet to be proved that dietary soy will stop osteoporosis, a synthetic isoflavone, ipriflavone, has been used in Japan and Europe to treat osteoporosis. Large doses of soy (6-8 servings per day) are believed by some to help this condition as well. 

The possible role of isoflavonoids in the prevention of cancer and in particular hormone-dependent cancers such as breast and prostate cancer is currently extensively investi-gated. " " In addition, consumption of soy foods rich in isoflavones has been weakly associated with reduced colon cancer. Colon cancer risk is influenced by estrogen exposure although the mechanism of action has not been fully elucidated, studies with estrogen receptor a (see Section 7.3.3) knockout mice indicate that it may be independent of estrogen receptor... 

Atkinson C, Warren RML, Sala E et al. Red clover-derived isoflavones and mammographic breast density a double-blind, randomized, placebo-controlled trial. Breast Cancer Res. 6, R170-R179, 2004. 

Few studies have been carried out in infants fed on soya formula. Absorption of isoflavones by the infant was demonstrated from the appearance of daidzein and genistein in the urine of 4-month-old infants fed soy formulas. Equol was not detected in the urine [94]. A later study by Setchell et al [95] did not confirm these results because equol was not detectable or present only in traces in the serum of 4-month-old infants fed soya infant formulas. Isoflavone concentration in human breast milk increased after the consumption of a soya-rich diet, but their contribution seems trivial in comparison to that from soy infant formulas [93]. 

Considerable evidence exists from epidemiological and experimental studies for preventive effects of soy or isoflavones against chronic diseases including cancer (breast, prostate, colorectal, lung), osteoporosis, cardiovascular disorders, and menopausal symptoms, but this is not always consistent [Adlercreutz... 

Zheng W, Dai Q, Custer LJ, Shu X-O, Wen W-Q, Jin F, Franke AA. 1999. Urinary excretion of isoflavones and the risk of breast cancer. Cancer Epidemiol Biomark Prev 8 35 10. 

Cotterchio M, Boucher BA, Kreiger N, Mills CA, Thompson LU. 2008. Dietary phytoestrogen intake-lignans and isoflavones-and breast cancer risk (Canada). Cancer Causes Control 19 259-272. 

Magee, P.J., McGlynn, H., and Rowland, I.R. 2004. Differential effects of isoflavones and lignans on invasiveness of MDA-MB-231 breast cancer ceff in vitro. Cancer Lett. 208, 35-41. 

Vaclavikova et al. [216] have investigated the effect of 13 flavonoid derivatives—aurones, chalcones, flavones, flavonols, chromones, and isoflavones—on 14 C-paclitaxel transport in two human breast cancer cell lines, the doxorubicin-resistant NCI/ADR-RES and sensitive MDA-MB-435. The compounds with known binding affinity toward the NBD of P-gp were selected. The four aurones studied most effectively inhibited P-gp-related transport in the resistant fine in comparison with other groups of flavonoids. The aurones also most effectively increased the intracellular accumulation of paclitaxel and decreased its efflux. The results obtained did not always correlate with the binding of flavonoid derivatives to P-gp, so this indicated that the binding was not the only factor influencing the transport of paclitaxel. The different aspects of inhibition of P-gp by polyphenols was recently reviewed by Kitagawa [212],... 

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