Sirpa Rasku

Isoflavonoids and lignans in legumes: nutritional and health aspects in humans

Abstract Dietary factors are considered important environmental risk determinants for Western diseases. Studies have revealed beneficial or protective effects of the consumption of legumes with regard to hypercholesterolaemia and coronary heart disease, obesity, diabetes mellitus, and menopause. During the last decade attention has been focused on soy and soybean products. Several constituents have been isolated: isoflavones, phytosterols, protease inhibitors, inositol hexaphosphate, and saponins. Our interest concentrates on hormone-like bisphenolic phytoestrogens of dietary origin, the lignans and isoflavonoids. Their glycosides, converted by gut bacteria to mammalian derivatives with weak estrogenic and antioxidative activity, originate in leguminous seeds. We developed an isotope dilution gas chromatography-mass spectrometry method for quantitative determination of the isoflavones, formononetin, biochanin A, daidzein, genistein and coumestrol, and the lignans secoisolariciresinol and matairesinol, in food samples. We measured the four isoflavonoids and coumestrol, and, for the first time, the two lignans in 52 leguminous seeds and found high concentrations of isoflavonoids (0–1853.35 mg/kg; 0–7.3 mmol/kg dw) but lower amount of lignans (0–15.85 mg/kg; 0.05 mmol/kg dw). The highest plasma levels of their metabolites are found in individuals living in countries or regions with low cancer and cardiovascular disease incidence and these are probably sufficient to influence intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation, and angiogenesis. Leguminous seeds, therefore, in respect to their abundant concentrations of phytoestrogens, are strong candidates for a role as natural cancer-protective food.

An isotope dilution gas chromatographic-mass spectrometric method for the simultaneous assay of estrogens and phytoestrogens in urine.

The metabolism of endogenous estrogens is complicated and certain metabolic patterns may reflect an individual risk of estrogen-dependent diseases such as breast cancer. Since the 1960s we have been constantly involved in developing estrogen profiling methods, in the beginning using gas chromatography and later gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode (SIM) and finally utilizing isotope dilution (ID-GC-MS-SIM). The addition of the dietary phytoestrogens to the profile rendered the method even more complicated. The present work presents the final estrogen profile method for 15 endogenous estrogens, four lignans, seven isoflavonoids and coumestrol in one small urine sample (1/150th of a 24 h human urine sample, minimum 2.5-5 ml) with complete validation including investigations as to the precision, sensitivity, accuracy and specificity. The method does not include the minimal amounts of unconjugated estrogens in urine. It may also be used for animal (e.g. rat and mouse) urine using a minimum of 2 ml of usually pooled sample. Despite its complexity it was found to fulfill the reliability criteria, resulting in highly specific and accurate results.

Synthesis of isoflavonoid deuterium labeled polyphenolic phytoestrogens

Abstract Deuteration methods are described for the synthesis of new stable deuterium labeled isoflavonoids, [8,3′,5′-D 3 ]-daidzein 4a , [8,3′,5′-D 3 ]-formononetin 4b , [2′,3′,5′,6′-D 4 ]-biochanin A 4c , [6,8,3′,5′-D 4 ]dihydrodaidzein 5a , [3,6,8,3′,5′-D 5 ]-dihydrodaidzein 5b , [3,2′,3′,5′,6′-D 5 ]-dihydrogenistein 5c and [2,4,8,10-D 4 ]-coumestrol 6 , using D 3 PO 4 ·BF 3 /D 2 O as a deuteration reagent. Positions of deuterium labels and isotopic purities were determined by NMR and mass spectrometry. The relative ease of H/D exchange at the various aromatic sites is discussed.

Synthesis of D4-genistein, a stable deutero labeled isoflavone, by a perdeuteration — Selective dedeuteration approach

Isotopically labile D6-genistein 3, obtained by D3PO4/BF3 treatment of genistein 1, is dedeuterated to the stable D4-genistein 4 by methanolic HCl.

Lignans and Isoflavonoid Polyphenols in Tea and Coffee

Tea (camellia sinensis) has been revealed to contain numerous polyphenols (flavanols, catechins, flavonols, flavonediols, phenolic acids, bisflavonols, theaflavins, thearubigens, and other oligomers) and theophylline, which may have both beneficial and hazardous effects in humans. Consumption of tea has been advocated to play a role in prevention of cancer, coronary heart disease, and atherosclerosis (Imai and Nakachi, 1995; Kohlmeier et al., 1997; Jankun et al., 1997; Bushman, 1998; Ahmad and H, 1999; Weisburger, 1999). Simultaneously, recent international epidemiological comparisons have linked the semivegetarian diet of Asiatics with a reduced incidence of chronic diseases (i.e., hormone-dependent cancers and coronary heart disease), indicating that some nonnutrient compounds in that diet may contribute to homeostasis and thus have a role in the maintenance of health (Adlercreutz, 1984, 1990, 1995). High consumption of legumes, (mainly soy in different forms), teas (particularly green tea), and rice differentiate the Asian diet from theWestern diet. We reasoned, based

Synthesis of deuterated plant lignans for gas chromatography-mass spectrometry analysis.

Stabile deuterated plant lignans D(6)-matairesinol, D(8)-secoisolariciresinol, and D(8)-anhydrosecoisolariciresinol are synthesized to be used as internal standards in isotope dilution technique of gas chromatography-mass spectrometry in the selected ion monitoring mode.