Analysis of plasma isoflavones by reversed-phase HPLC-multiple reaction ion monitoring-mass spectrometry

Coward, Lori; Kirk, Marion; Albin, Nicolas; Barnes, Stephen

doi:10.1016/0009-8981(95)06242-4

Cited by 181 publications

(96 citation statements)

References 31 publications

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“…Although phytoestrogens have been described as highly stable (Franke et al, 1998 ), the long -term storage stability ( years ) has not been addressed and the possibility of degradation or loss of analytes during storage could not be discounted. However, the substantial number of serum samples containing non -detectable levels of equol and matairesinol was consistent with the levels of lignans and isoflavonoids found in published studies (Adlercreutz et al, 1993b,c;Coward et al, 1996;Setchell et al, 1997;Barnes et al, 1998;Franke et al, 1998 ). The minor discrepancies between our NHANES III data and published levels may be due to differences in the dietary habits and metabolism of distinct subpopulations.…”

Section: Applicationsupporting

confidence: 91%

HPLC-MS/MS method for the measurement of seven phytoestrogens in human serum and urine

Valentín-Blasini

Blount

Rogers

et al. 2000

J Expo Sci Environ Epidemiol

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The elevated exposure of children to hormonally active dietary phytoestrogens has led to the need for rapid, sensitive, and precise assays for phytoestrogen metabolites in physiological matrices. Here we report the development of a high -performance liquid chromatography ( HPLC ) MS / MS method for the quantitative detection of seven phytoestrogens in human serum and urine. The method uses enzymatic deconjugation of the phytoestrogen metabolites followed by solid phase extraction ( SPE ) and reverse -phase HPLC. The phytoestrogens are detected using a Sciex API III heated nebulizer atmospheric pressure chemical ionization ( HN -APCI ) interface coupled with tandem mass spectrometry. This method allows the detection of the primary dietary phytoestrogens ( isoflavones and lignans ) in human serum and urine with limits of detection ( LODs ) in the low parts per billion range. The combination of tandem mass spectrometry and chromatographic separation of the analytes helps ensure the selectivity of the method. Stable isotope -labeled internal standards for all seven analytes improve the precision of the assay, resulting in interday CV values of < 10% for most compounds studied. The accuracy and precision of the method were monitored over time using quality control ( QC ) samples containing known amounts of phytoestrogens. The majority of phytoestrogens in human sera and urine are present as their glucuronide and sulfate conjugates. Therefore, the thoroughness of deconjugation for each sample was monitored by the addition of a conjugated internal standard and subsequent detection of deconjugated compound. This method proves to be efficacious for measuring baseline urinary phytoestrogen levels in the American population and should prove useful for assessing the modulatory effects of dietary phytoestrogens on endocrine disrupter action in children.

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Section: Applicationsupporting

confidence: 91%

HPLC-MS/MS method for the measurement of seven phytoestrogens in human serum and urine

Valentín-Blasini

Blount

Rogers

et al. 2000

J Expo Sci Environ Epidemiol

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“…The sera were separated and stored frozen at À20 1C or lower until they were transported on dry ice to the laboratory of SRL Co. (Hachioji, Tokyo, Japan). The serum concentrations of daidzein, genistein and equol were also measured in all subjects by reverse-phase highperformance liquid chromatography-multiple reaction ion monitoring-mass spectrometry at the laboratory of SRL Co. 23 The lower limit of detection of the serum isoflavones was 0.5 ng ml À1 in this assay. Since the proportion of men having the serum equol levels above this limit is reportedly low, the volunteers having serum equol levels of^0.5 ng ml À1 were defined as equol producers.…”

Section: Subjects and Study Designmentioning

confidence: 99%

“…Since the proportion of men having the serum equol levels above this limit is reportedly low, the volunteers having serum equol levels of^0.5 ng ml À1 were defined as equol producers. 18,23 …”

Section: Subjects and Study Designmentioning

confidence: 99%

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men

Fujimoto

Tanaka

Hirao

et al. 2008

Prostate Cancer Prostatic Dis

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Racial differences in the incidence of prostate cancer are manifest worldwide, possibly due to the different dietary habits. To elucidate the relationship between the recent trend of phytoestrogenic isoflavone intake and the increased incidence of prostate cancer in Japan, we conducted an agestratified dietary survey of soybean foods in 102 Japanese healthy men (age range: 10-59 years) and measured the serum isoflavones and equol levels in them and 100 Korean healthy men. The intergroup comparison among the age-stratified groups showed significant differences in the daily intake of genistein and daidzein between the teenager group and the other groups of age^30 years (Po0.05). In the Japanese study, the proportion of equol producers in the teenager group was 10%, being significantly the lowest among the age-stratified groups. The proportions of equol producers in the age-stratified groups from 10 to 49 years were also significantly lower than those in the fifties. The equol non-producers consumed significantly less amounts of isoflavones than the equol producers. In the Korean study, the proportions of equol producers were 45% in the teenager and 40% in the twenties and thirties, being significantly lower than in the forties (80%) and fifties (65%). The decreased intake of isoflavones, low serum level of equol and low incidence of equol production in the young generation may become potential risk factors for prostate cancer not only in Japan but also in Korea in the near future. Elucidating the mechanism of equol production may be promising in developing strategies for chemoprevention against prostate cancer.

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“…Serum isoflavones (genistein, daidzein, glycitein, dihydrodaidzein, O-desmethylangiolensin, equol) were measured by LC-multiple reaction ion monitoring-mass spectrometry as previously described (25). The internal standards, phenolphthalein βglucuronide, 4-methylumbelliferone sulfate and chrysin, were added to each serum sample.…”

Section: Serum Isoflavonesmentioning

confidence: 99%

Effect of a daily supplement of soy protein on body composition and insulin secretion in postmenopausal women

Sites

Cooper

Toth

et al. 2007

Fertility and Sterility

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Objective: To determine if a supplement of soy protein improves body composition, body fat distribution, and glucose and insulin metabolism in non-diabetic postmenopausal women compared to an isocaloric casein placebo. Results: Weight by DXA did not change between groups (+1.38 ± 2.02 kg for placebo vs. +0.756 ± 1.32 kg for soy, p=0.48, means ± S.D.). Total and subcutaneous abdominal fat increased more in the placebo compared to the soy group (for differences between groups in total abdominal fat: +38.62 ± 22.84 cm 2 for placebo vs. −11.86 ± 31.48 cm 2 for soy, p=0.005; subcutaneous abdominal fat: +22.91 ± 28.58 cm 2 for placebo vs. −14.73 ± 22.26 cm 2 for soy, p=0.013). Insulin secretion, visceral fat, total body fat, and lean mass did not differ between groups. Isoflavone levels increased more in the soy group. Conclusion:A daily supplement of soy protein prevents the increase in subcutaneous and total abdominal fat observed with an isocaloric casein placebo in postmenopausal women.

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Analysis of plasma isoflavones by reversed-phase HPLC-multiple reaction ion monitoring-mass spectrometry

Cited by 181 publications

References 31 publications

HPLC-MS/MS method for the measurement of seven phytoestrogens in human serum and urine

HPLC-MS/MS method for the measurement of seven phytoestrogens in human serum and urine

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men

Effect of a daily supplement of soy protein on body composition and insulin secretion in postmenopausal women

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