Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 1/8/2001
Publication Date: 3/17/2001
Citation: CIMINO, C.O., SHELNUTT, S.R., WIGGINS, P., CROOK, T., ZHANG, Z., BADGER, T.M. PHARMACOKINETICS OF SOY ISOFLAVONE SULFATES IN MEN AND WOMEN FED A SOY BEVERAGE. JOURNAL OF FEDERATION OF AMERICAN SOCIETIES FOR EXPERIMENTAL BIOLOGY. 2001. v. 15(4). p. A1099. Abstract No. 843.5. Interpretive Summary: A large part of the health benefits of a soy-containing diet is thought to be the isoflavones bound to the soy protein. These phytochemicals are circulating in the blood after a soy meal. In order to understand the actions of isoflavones, it is important know what the time course with which they are absorbed, what the concentrations are and how long they remain in the circulation. Twelve adults were studied and the time course, concentrations and durations were determined for each major isoflavone. This information will help in the design of future studies in infants fed soy formula where these investigators are interested in determining the long-term health consequences of early soy intake.
Technical Abstract: Genistein (GEN) and Diadzein (DAID) are the major isoflavones bound to soy protein isolates and they circulate as glucuronides (G) and sulfates (S) following a soy meal. Endocrine sensitive tissues such as breast have sulfatases capable of deconjugating the sulfated genistein and diadzein. Little is known about the pharmacokinetics (PKs) of these important conjugates. We studies 12 adults who consumed soy protein (1-mg/kg GEN equivalents and 0.6 mg/kg DAID equivalents, a gift of Protein Technologies Int.) to determine their PKs. Plasma and urine were collected for 48 hr and digested with: 1) Helix pomatia (sulfatase/b-glucurinidase) enzymes (+/- d-saccharic 1,4 lactone); or 2) b-glucuronidase. Samples were extracted and analyzed by LC/MS for the deconjugated aglycones and metabolites, and further analyzed using noncompartmental PK methods. The mean (+/- SEM) time to peak plasma concentrations (Tmax) for GEN-S, DIAD-S and DIAD-G was shorter than GEN-G (Tmax,4.5-5.2 +/- 0.6 hr). The mean peak plasma levels (Cmax) were: GEN-S 140.7 nM; DIAD-S 236.2 nM; GEN-G 498.8 nM; DIA-G 338.8 nM. The terminal half-life (tl/2Iz) for each of these 4 major isoflavone-conjugates differed significantly from each other in plasma (range 4.0 - 12.3 h). These results demonstrate that while differences exist between the PKs of glucuronides and sulfates, the mean values are within the same general range.