Genistein detection

Each figure represents the mean and standard error of three repetitions. The exudation pattern from the first 5 days of collection does not appear to differ from the second 5 days of collection. The relative levels of soyasapogenols and genistein within the root are not different at 15 days after germination, nor do they differ at 3 months of age. Soyasapogenols were not detected in shoot portions of seedlings. 

In 1987, Ken Setchell first described the method for the isolation of phytoestrogen in soy (Setchell et al., 1987). The phytoestrogens daidzein, genistein, coumestrol, formononetin, and biochanin-A were separated on a Cl8 reversed-phase column (Hypersil ODS) with methanol-0.1 M ammonium acetate buffer, pH 4.6 (60 40 v/v), as eluent. The retention and resolution were affected by buffer concentrations, pH type, and proportion of organic solvent in the mobile phase. Detection in the low picograms range was achieved with an electrochemical detector, and the compounds were positively identified by HPLC-thermospray mass spectrometry. 

Satterfield, M., Black, D.M., and Brodbelt, J.S., Detection of the isoflavone aglycones genistein and daidzein in urine using solid-phase microextraction-high-performance liquid chromatography-electrospray ionization mass spectrometry, J. Chromatogr. B, 759, 33, 2001. 

Similar plasma concentrations were detected for daidzein, genistein and equol in adults consuming modest quantities of soy foods containing about 50 mg/d of total isoflavones [91]. 

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]. 

Some natural chemicals such as those produced by fungi (zearalenone) and plants (genistein) may also be oestrogenic and have hormone-like actions. Such chemicals can be detected in the effluent from paper miUs and are suspected of causing masculinization of female fish. However, all... 

Chandra and Nair (1996) used supercritical carbon dioxide fluid extraction for extracting daidzein, genistein, biochanin A and formononetin from soy products. The separation was done by HPLC with a C18 column, followed by UV detection at 254 nm. Ninety-three percent of the isoflavones were extracted by using the supercritical fluid carbon dioxide with 20% ethanol at 50°C and 600 atmospheric pressure. 

Aussenac et al. (1998) used capillary zone electrophoresis with UV detection at 260 nm to analyze isoflavones in soybean seeds of various varieties grown in various locations. Methanol was used for extraction. Total extraction was not affected by temperature but was affected by the composition of the solvent. Electrophoresis was conducted at pH 10.5, at which the isoflavones were weak acids and were ionized. Boric acid was added to form a negatively charged borate-isoflavone complex. A fast capillary electrophoresis method was also developed by Vanttinen and Moravcova (1999) to determine daidzein and genistein after enzyme hydrolysis in soy products. Photodiode array was used to detect the isoflavones at 254 and 268 nm, respectively. Minimum detection was 0.4 mg/L. p-Nitrophenol was used as an internal standard. 

However, EC-MS and EC-MS/MS offer a better way to detect and identify phytoestrogens at low concentrations. An isoflavonoid genistein was detected by LC-ESl-MS and positively identified by LC-ESI-MS-MS in bleached Kraft mill effluent. Genistein was quantihed at a concentration of 30/rg/kg in air-dried wood pulp and concentrations of 13.1 and 10.5 /rg/1 in untreated and treated (final) effluent, respectively. These concentrations could contribute to the alterations in sex steroid levels and reduced reproductive capacity observed in hsh capture near the discharges of pulp mills. 

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