Prostatic fluid concentrations of isoflavonoids in soy consumers are sufficient to inhibit growth of benign and malignant prostatic epithelial cells in vitro
Prostate, 2005 December
Other studies have shown that equol and the soy isoflavones daidzein and genistein have an anti-proliferative effects on cultured prostatic epithelial cells. The composition of the gut flora and the intestinal metabolism of the soy isoflavones are likely to influence the ability of soy to prevent prostate cancer. The effect of the isoflavone glycitein and its metabolites are not known. The aim of this study was to investigate the in vitro activity of glycitein and its metabolites. The active ranges of concentrations were then were compared to that found in human prostatic fluid and plasma samples. The researchers found that the concentrations of genistein, equol and daidzein in the prostatic fluid were often within the ranges that reduce prostatic epithelial cells growth in vitro. The isoflavones showed large differences in activity on prostate cancer cells. Glycitein had significant effects on both the prostatic epithelial cells and prostate cancer cells. When the isoflavones were used in levels found in prostate fluid synergistic effects were observed. The study concluded that different sensitivities of prostatic epithelial cells to isoflavones and the observed synergistic effects makes the intake multiple isoflavones metabolites a potential cure for preventing prostate cancer.
Isoflavone genistein and daidzein up-regulate LPS-induced inducible nitric oxide synthase activity through estrogen receptor pathway in RAW264.7 cels
Biochemical Pharmacology, 2005 Dec 19;71(1-2):108-14
The soy isoflavones genistein and daidzein have estrogenic and can bind to the estrogen receptors. The purpose of this study was investigated that the effect of estrogen (7beta-estradiol) and the isoflavones genistein and daidzein on nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) activity in mouse macrophage-like cells. Both estrogen and isoflavones significantly increased lipopolysaccharide-induced nitric oxide production and inducible nitric oxide synthase expression. Isoflavones also increased the production of tumor necrosis factor-alpha.
Suppression of arachidonic acid metabolism and nitric oxide formation by kudzu isoflavones in murine macrophages.
Molecular Nutrition and Food Research, 2005 December, 49(12):1154-9
The aim of this study was to measure the inhibitory effect of kudzu isoflavones on arachidonic acid metabolism and nitric oxide production in macrophages. Jun M. and colleagues found that the isoflavones daidzein, genistein, biochanin A and formononetin significantly suppressed arachidonic acid release. Biochanin A showed the strongest inhibitory effect, whereas the isoflavones puerarin and daidzin showed lower activities. Biochanin showed the strongest inhibition against nitric acid formation, followed by genistein, daidzein, formononetin and daidzein. These obtained results may explain the anti-inflammatory and anti-carcinogenic properties of kudzu isoflavones.
Isoflavones modulate the glucuronidation of estradiol in human liver microsomes.
Carcinogenesis, 2005 December, 26(12):2172-8
Epidemiological studies link soyfood consumption with lower incidence of hormonal cancer in Asian countries. The soy isoflavones daidzein and genistein are believed to protect against cancers induced by estrogen. This study investigated the influence of the isoflavones daidzein and genistein on the modulation of the glucuronidation of estrogen in human hepatic microsomes. The researchers found that daidzein stimulated the 3-glucuronidation, whereas genistein inhibitive effect. The enhanced rate of glucuronidation of estrogen by daidzein and its metabolites may explain the protection effect of soy isoflavones against hormonal cancer.
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