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Flavonoids constitute a group of polyphenols widely distributed in plants and are assumed to have beneficial effects on human health when present in food. The phenolic content of apple fruit skin and leaves was determined at the developmental stage of each organ. Phenolic levels decreased on a dry weight basis during the seasonal development of fruits and leaves with respect to their ontogenesis but the single compounds did not behave uniformly. A shift in flavanol pools from monomeric to oligomeric structures during fruit growth indicated the biosynthetic tendency towards the formation of procyanidins at the end of the growing period. A gas chromatography-mass spectrometry (GC-MS) method was developed for the separation and determination of three major flavones: sinensetin (SEN), rutin (RU) and 3'-hydroxy-5, 6, 7, 4'-tetramethoxyflavone (TMF) and rosmarinic acid (RA), a caffeic acid derivative in the pink skin of apple fruit. The GC-MS method was applied for the quantification of SEN, RU, TMF and RA in apple fruit collected from different local markets of Bangladesh during the period of November 2008. Apple fruit skin contains several bioactive phytochemicals including polyphenols such as flavones and phenolic acids. Dehydrated apple skin powder was used to evaluate the recovery of selected flavones and rosmarinic acid using water, methanol, acetone, chloroform, aqueous 50% methanol, and aqueous 70% acetone at 40 °C. The retrieved extracts were subjected to qualitative and quantitative GC-MS analysis. Highest amount of sinensetin (SEN) and rutin (RU) was found in the chloroform extract, which was obtained for 4 to 6 hours of extraction at 40°C. Higher proportion of 3'-hydroxy-5, 6,7,4'-tetramethoxyflavone (TMF) was obtained in pure acetone and as well as 70% acetone where the extraction period 4 to 6 hours, respectively. Similar yield of rosmarinic acid (RA) was obtained in aqueous 70% acetone extracts when the periods of extraction were 2, 4, 6 and 8 hours, respectively. Key words: Quantification, Malus sylvestris, Lipophillic flavones, GC-MS, INTRODUCTION Phenolic acids and flavonoids are secondary metabolites found in most of the plants. These compounds protect plants against ultraviolet radiation, pathogens, and herbivores [1]. The daily intake of flavonoids [...]

Serum C-reactive protein (CRP) is a biomarker for chronic inflammation and a sensitive risk factor for cardiovascular diseases. Though CRP has been reported to be related to food intake, there is no documentation of a direct association with flavonoid intake. We aimed to test the associations between dietary flavonoid intake and serum CRP concentrations among U.S. adults after adjusting for dietary, sociodemographic, and lifestyle factors. Data from the NHANES 1999-2002 were used for this cross-sectional study. Subjects were [greater than or equal to] 19-y-old adults (n = 8335), and did not include pregnant and/or lactating women. Flavonoid intake of U.S. adults was estimated by the USDA flavonoid databases matched with a 24-h dietary recall in NHANES 1999-2002. The serum CRP concentration was higher in women, older adults, blacks, and smokers, and in those with high BMI or low exercise level, and in those taking NSAID, than in their counterparts (P< 0.01 ). Intakes of apples and vegetables were inversely associated with serum CRP concentrations after adjusting for covariates (P < 0.05). Total flavonoid and also individual flavonol, anthocyanidin, and isoflavone intakes were inversely associated with serum CR P concentration after adjusting for the covariates (P < 0.05). Among the flavonoid compounds investigated, quercetin, kaempferol, malvidin, peonidin, daidzein, and genistein had inverse associations with serum CRP concentration (P < 0.05). These associations did not change even after the additional adjustment for fruit and vegetable consumption. Our findings demonstrate that intake of dietary flavonoids is inversely associated with serum CRP concentrations in U.S. adults. Intake of flavonoid-rich foods may thus reduce inflammation-mediated chronic diseases.

The dietary flavonoid quercetin reduces blood pressure and improves endothelial function in several rat models of hypertension. We analyzed the effects of quercetin and its methylated metabolite isorhamnetin on the aortic endothelial dysfunction induced by incubation with angiotensin II (Angll) in vitro for 6 h. Angll diminished the relaxant responses to acetylcholine in phenylephrine-contracted aorta. Coincubation with quercetin or isorhamnetin, or addition of superoxide ([0.sub.2]-) dismutase or apocynin to the assay medium, prevented these inhibitory effects. At 6 h, Angll induced a marked increase in [0.sub.2]- production as measured by dihydroethidium fluorescence, which was prevented by quercetin and isorhamnetin. Angll also increased the expression of p[47.sup.phox], a regulatory subunit of the membrane NADPH oxidase. Immunohistochemical analysis revealed that overexpression of p[47.sup.phox] occurred mainly in the medial layer, p[47.sup.phox] overexpression was also prevented by quercetin and isorhamnetin. Taken together, these results show for the first time, to our knowledge, that quercetin and isorhamnetin prevent Angll-induced endothelial dysfunction by inhibiting the overexpression of p[47.sup.phox] and the subsequent increased [0.sub.2]- production, resulting in increased nitric oxide bioavailability. J. Nutr. 137: 910-915, 2007.

This article provides an overview of current research on flavonoids as presented during a workshop entitled, 'Flavonoids and Heart Health,' held by the ILSI North America Project Committee on Flavonoids in Washington, DC, May 31 and June 1, 2005. Because a thorough knowledge and understanding about the science of flavonoids and their effects on health will aid in establishing dietary recommendations for bioactive components such as flavonoids, a systematic review of the science of select flavonoid classes (i.e., flavonols, flavones, flavanones, isoflavones, flavan-3-ols, anthocyanins, and proanthocyanidins) was presented. The objectives of the workshop were to 1) present and discuss current research on flavonoid intake and the relation between flavonoids and heart health; 2) develop information that could lead to expert consensus on the state-of-the-science of dietary intake of flavonoids on heart health; and 3) summarize and prioritize the research needed to establish the relations between specific flavonoids and heart health. Presentations included the basics of the biology of flavonoids, including the types and distribution in foods, analytical methodologies used to determine the amounts in foods, the bioavailability, the consumption patterns and potential biomarkers of intake, risk assessment and safety evaluation, structure/ function claims, and the proposed mechanism(s) of the relation between certain flavonoids and heart health endpoints. Data presented support the concept that certain flavonoids in the diet can be associated with significant health benefits, including heart health. Research gaps were identified to help advance the science.

Inflammation and oxidative stress are associated with cancer, atherosclerosis, and other chronic diseases. Dietary flavonoids have been reported to possess antiinflammatory and antioxidant properties, but their mechanisms of action and structure-activity relations have not been fully investigated. We hypothesized that differences in antioxidant activity between the structurally similar flavones, luteolin and chrysin (differing only in B-ring hydroxylation patterns), would differentially affect inflammation-associated Cox-2 expression and PG[E.sub.2] formation. Pretreatment of RAW 264.7 macrophage-like cells with 25, 50, or 100 [micro]mol/L concentrations of luteolin inhibited lipopolysaccharide (LPS)-induced Cox-2 protein expression (P < 0.0001). Chrysin pretreatment did not reduce LPS-induced Cox-2 protein expression at any level tested. Conversely, both luteolin and chrysin completely suppressed LPS-induced PG[E.sub.2] formation (P < 0.001). Luteolin, but not chrysin, inhibited xanthine/xanthine oxidase-generated superoxide formation at 100 [micro]mol/L in a cell-free system (P < 0.001). Although both luteolin and chrysin reduced LPS-induced hydroxyl radical formation relative to the positive control (P < 0.001), luteolin was superior to chrysin (P = 0.003). In summary, luteolin and chrysin suppressed PG[E.sub.2] formation equally well, despite differential effects on Cox-2 protein expression and on superoxide and hydroxyl radical scavenging. These data indicate that flavones may display similar antiinflammatory activity via different mechanisms. KEY WORDS: * luteolin * chrysin * cyclooxygenase-2 * prostaglandin [E.sub.2] * reactive oxygen species

The molecular understanding of nutritional factors in the process of host factor-mediated activation of the intestinal epithelium may play an important role in the assessment of adjunct nutritional therapy for chronic intestinal inflammation. We characterized the molecular mechanisms of flavonoids including apigenin, luteolin, genistein, 3'-hydroxy-flavone, and flavone in inhibiting tumor necrosis factor-[alpha] (TNF)-induced interferon-induced protein (IP)-10 gene expression in the murine intestinal epithelial cell (IEC) line Mode-K. We demonstrated that 3'-hydroxy-flavone but not the chemical core structure flavone blocked TNF-[alpha]-induced nuclear factor (NF)-[kappa]B transcriptional activity and IP-10 expression at the level of NF-[kappa]B/I[kappa]B[alpha] phosphorylation/degradation by inhibiting I[kappa]B kinase activity. Although 3'-hydroxy-flavone effectively triggered p38 mitogen-activated protein kinase signaling and late caspase-3 cleavage, the induction of apoptotic cell death in TNF-activated IEC was not the primary mechanism inhibiting NF-[kappa]B transcriptional activity and IP-10 expression. In addition to the compound-specific inhibition of TNF-induced NF-[kappa]B DNA binding and NF-[kappa]B transcriptional activity, apigenin and luteolin selectively blocked Akt phosphorylation/activity. The ability of these polyphenolic compounds to target various signal transduction pathways was further supported by the observation that luteolin and 3'-hydroxy-flavone selectively induced interferon regulatory factor (IRF)-1 degradation. Finally, we showed that genistein blocked IP-10 but not IL-6 expression through NF-[kappa]B, IRF, and Akt independent mechanisms, demonstrating the functional diversity of flavonoids in inhibiting proinflammatory processes in IEC. In conclusion, we provide molecular evidence for the presence of characteristic inhibition patterns of these polyphenolic compounds to inhibit proinflammatory gene expression in IEC through the specific modulation of the NF-[kappa]B, IRF and Akt signaling pathways. KEY WORDS: * intestinal epithelial cell pathology * inflammation * NF-[kappa]B signaling * flavonoids

Cocoa beans have historically been used as a treatment for diarrhea, leading us to hypothesize that polyphenols contained in cocoa inhibit intestinal [Cl.sup.-] secretion. In this study, the dose-dependent effects of flavonoid compounds present in cocoa, or molecularly closely related compounds, were tested on forskolin-stimulated cystic fibrosis transmembrane conductance regulator (CFTR)-mediated [Cl.sup.-] secretion across T84 colonic epithelia in Ussing chambers. Addition of cocoa extract or cocoa flavanols to the mucosal side of tissues caused partial inhibition following Michaelis-Menten kinetics and resulted in a rank order of maximum blocker effects as follows: epicatechin > catechin [greater than or equal to] standardized cocoa preparation [greater than or equal to] procyanidin B2. Half-maximal blocker concentrations ([K.sub.1]) were not substantially different between the tested preparations and were in the range of 100 [micro]mol/L. For comparison, the structurally related flavonoids, quercetin and luteolin, caused a total block of [Cl.sup.-] currents with [K.sub.i] values similar to the cocoa flavanols tested. Morin and baicalein were less effective blockers. Effects of test compounds on mucosal redox potential did not correlate with blocker activity. These data indicate that cocoa flavanols target intestinal CFTR [Cl.sup.1] transport and may serve as mild inhibitors of cAMP-stimulated [Cl.sup.-] secretion in the intestine. KEY WORDS: * diarrhea * CFTR [Cl.sup.-] channel * cocoa * flavonoids * CFTR blocker * redox potential

Consumption of tree nuts such as almonds has been associated with a reduced risk of coronary heart disease. Flavonoids, found predominantly in the skin of almonds, may contribute to their putative health benefit, but their bioactivity and bioavailability have not previously been studied. Almond skin flavonoids (ASF) were extracted with HCI:[H.sub.2]O:methanol (1:19:80) and their content of catechins and flavonols identified by HPLC with electrochemical detection. ASF bioactivity was assessed in vitro by their capacity to increase the resistance of human LDL to oxidation induced by 10 [micro]mol/L [Cu.sup.2+]. ASF from 0.18 to 1.44 [micro]mol gallic acid equivalent (GAE)/L increased the lag time to LDL oxidation in a dose-dependent manner (P [less than or equal to] 0.0001). Combining ASF with vitamin E or ascorbic acid extended the lag time >200% of the expected additive value (P [less than or equal to] 0.05). The bioavailability and in vivo antioxidant activity of 40 [micro]mol ASF were examined in BioF1B hamsters. Peak plasma concentrations of catechin, epicatechin, and flavonols (quercetin, kaempferol, and isorhamnetin) occurred at 60, 120, and 180 min, respectively. The concentration of isorhamnetin was significantly elevated in liver at 180 min. Absorbed ASF enhanced the ex vivo resistance of hamster LDL collected at 60 min to oxidation by 18.0% (P = 0.028), and the in vitro addition of 5.5 [micro]mol/L vitamin E synergistically extended the lag time of the 60-min sample by 52.5% (P [less than or equal to] 0.05). Thus, ASF possess antioxidant capacity in vitro; they are bioavailable and act in synergy with vitamins C and E to protect LDL against oxidation in hamsters. KEY WORDS: * almonds * antioxidants * bioavailability * flavonoids * synergy

Nutritional, or dietary oxidative stress denotes a disturbance of the redox state resulting from excess oxidative load or from inadequate nutrient supply favoring prooxidant reactions. Low intake or impaired availability of dietary antioxidants including vitamins E and C, carotenoids, polyphenols, and other micronutrients (e.g., selenium) weakens the antioxidant network. Postprandial oxidative stress, as a subform of nutritional oxidative stress, ensues from sustained postprandial hyperlipidemia and/or hyperglycemia and is associated with a higher risk for atherosclerosis, diabetes, and obesity. In Western societies, a significant part of the day is spent in the postprandial state. Unsaturated fatty acids incorporated into LDL and oxidized LDL are an atherogenic factor. Lipid hydroperoxides present in the diet are absorbed, contributing to the prooxidant load. In hyperlipidemic and hyperglycemic subjects, endothelium-dependent vasodilation is impaired in the postprandial state, making postprandial oxidative stress an important factor modulating cardiovascular risk. Postprandial oxidative stress is attenuated when dietary antioxidants are supplied together with a meal rich in oxidized or oxidizable lipids. Ingestion of dietary polyphenols, e.g., from wine, cocoa, or tea, improves endothelial dysfunction and lowers the susceptibility of LDL lipids to oxidation. Polyphenols affect endothelial function not solely as antioxidants but also as modulatory signaling molecules. KEY WORDS: * antioxidants * diet * flavonoids * nutritional oxidative stress

We reported recently that (-)epigallocatechin gallate and quercetin inhibited [H.sub.2][O.sub.2]-induced apoptosis through modulation of the expression of apoptosis-related Bcl-2 and Bax in endothelial cells. This study attempted to identify possible regulatory sites and mechanisms of antiapoptotic flavonoids, focusing on ROS-mediated signaling in HUVEC. The effects of apigenin on the signaling pathway downstream were compared. Submillimolar [H.sub.2][O.sub.2] caused >30% cell killing with intracellular oxidant generation. [H.sub.2][O.sub.2]-induced oxidant generation markedly decreased total intracellular glutathione (GSH) levels. Micromolar (-)epigallocatechin gallate and quercetin partially eliminated the dichlorodihydrofluorescein (DCF) and phospho-p53 staining, suggesting that these flavonoids inhibited the accumulation of intracellular oxidants and nuclear transactivation of p53 in [H.sub.2][O.sub.2]-exposed cells. In contrast, cells treated with apigenin remained DCF and phospho-p53 staining positive in response to [H.sub.2][O.sub.2]. (-)Epigallocatechin gallate significantly raised the total GSH level that had been depleted by [H.sub.2][O.sub.2]. Caspase-3 activity was enhanced by [H.sub.2][O.sub.2], and this increase was inhibited by (-)epigallocatechin gallate and quercetin.Additionally, the upregulation of caspase-3 activation was reversed by these flavonoids at [greater than or equal to]10 [micro]mol/L; these inhibitory effects were dose dependent. Western blot data revealed that [H.sub.2][O.sub.2] upregulated phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), which was rapidly reversed by quercetin within 30 min; [H.sub.2][O.sub.2] activation of c-Jun was downregulated. (-)Epigallocatechin gallate inhibited [H.sub.2][O.sub.2]induced phosphorylation of JNK and p38 MAPK after 60 min. These results reveal that quercetin blocks JNK and p38 MAPK-related signaling triggered by the oxidant and may regulate expression of apoptotic downstream genes, preventing apoptosis and promoting cell survival. (-)Epigallocatechin gallate may function as an antiapoptotic agent through other antiapoptotic pathways. KEY WORDS: * flavonoids * apoptosis * [H.sub.2][O.sub.2] * survival signaling

In light of the continuing need for effective anticancer agents, and the association of fruit and vegetable consumption with reduced cancer risk, edible plants are increasingly being considered as sources of anticancer drugs. Cranberry presscake (the material remaining after squeezing juice from the berries), when fed to mice bearing human breast tumor MDA-MB-435 cells, was shown previously to decrease the growth and metastasis of tumors. Therefore, further studies were undertaken to isolate the components of cranberry that contributed to this anticancer activity, and determine the mechanisms by which they inhibited proliferation. Using standard chromatographic techniques, a warm-water extract of cranberry presscake was fractionated, and an acidified methanol eluate (Fraction 6, or Fr6) containing flavonoids demonstrated antiproliferative activity. The extract inhibited proliferation of 8 human tumor cell lines of multiple origins. The androgen-dependent prostate cell line LNCaP was the most sensitive of those tested (10 mg/L Fr6 inhibited its growth by 50%), and the estrogen-independent breast line MDA-MB-435 and the androgen-independent prostate line DU145 were the least sensitive (250 mg/L Fr6 inhibited their growth by 50%). Other human tumor lines originating from breast (MCF-7), skin (SK-MEL-5), colon (HT-29), lung (DMS114), and brain (U87) had intermediate sensitivity to Fr6. Using flow cytometric analyses of DNA distribution (cell cycle) and annexin V-positivity (apoptosis), Fr6 was shown in MDA-MB-435 cells to block cell cycle progression (P < 0.05) and induce cells to undergo apoptosis (P < 0.05) in a dose-dependent manner. Fr6 is potentially a source of a novel anticancer agent. KEY WORDS: * anticancer agent * flavonoids * cranberry * breast cancer

The flavonol quercetin is one of the most prevalent flavonoids found in edible plants. In this study, the influence of dietary fat on oral bioavailability of quercetin was investigated. Quercetin (30 [micro]mol/kg body weight) was administered either as the lipophilic aglycone or as the more hydrophilic quercetin-3-O-glucoside in test meals differing in fat content (3, 17, or 32 g fat/100 g diet) to growing pigs. Blood samples were drawn repeatedly over a 24-h period and analyzed by HPLC. The main metabolite found in plasma was always conjugated quercetin. Quercetin bioavailability from each diet was always higher from the glucoside than from the aglycone. Irrespective of the chemical form applied, the bioavailability of quercetin was higher in the 17% fat diet compared with the 3% fat diet (P < 0.05). No further effect on bioavailability was observed when the flavonols were administered with diets containing 32% fat. The elimination of quercetin was significantly delayed after its application with fat-enriched diets (P < 0.05). Thus, in addition to the chemical form of the flavonol, the fat content of the diet influences oral bioavailability of quercetin. J. Nutr. 134: 1508-1511, 2004. KEY WORDS: * flavonoids * bioavailability * quercetin * fat * pigs

Quercetin has antioxidant, anti-inflammatory, antiproliferative and anticarcinogenic properties. In plant foods, quercetin occurs mainly bound to various sugars via a [beta]-glycosidic link. We hypothesized that lactase phlorizin hydrolase (LPH), an enzyme at the brush border membrane of intestinal cells, is involved in the in vivo intestinal uptake of quercetin-sugars. To study this, we measured the appearance of quercetin metabolites in plasma and perfusate after perfusing the jejunum and ileum with 50 [micro]mol/L quercetin-3-glucoside in an in situ rat perfusion model. LPH was inhibited by the selective LPH inhibitor N-butyldeoxygalactonojirimycin (0, 0.5, 2 or 10 mmol/L) (n = 5 rats/group). Quercetin in plasma and perfusion buffer was determined by HPLC with CoulArray detection. Results are given as means [+ or -] SEM. In the perfusion buffer, 13.8 [+ or -] 0.7 [micro]mol/L quercetin-3-glucoside was hydrolyzed during intestinal passage. Co-perfusion with 0.5, 2 and 10 mmol/L N-butyldeoxygalactonojirimycin resulted in 38% (P < 0.05), 50% (P < 0.01) and 67% (P < 0.01) less hydrolysis, respectively. Plasma concentrations of quercetin in the corresponding groups were 36% (P = 0.12), 55% (P < 0.01) and 75% (P < 0.01) lower than in controls (1.23 [+ or -] 0.22 [micro]mol/L). These data suggest that LPH is a major determinant of intestinal absorption of quercetin-3-glucoside in rats. KEY WORDS: * flavonoids * quercetin-3-glucoside * lactase phlorizin hydrolase * intestinal uptake * rats

Dietary soy protein has been shown to have several beneficial effects on cardiovascular health. The best-documented effect is on plasma lipid and lipoprotein concentrations, with reductions of ~10% in LDL cholesterol concentrations (somewhat greater for individuals with high pretreatment LDL cholesterol concentrations) and small increases in HDL cholesterol concentrations. Dietary soy protein improves flow-mediated arterial dilation of postmenopausal women but worsens that of men. Soy isoflavone extracts improve systemic arterial compliance, an indicator of atherosclerosis extent. Complete soy protein but not alcohol-washed soy protein reduces atherosclerosis of postmenopausal monkeys. No definite experimental evidence exists currently to establish that the cardiovascular benefits of soy protein are accounted for by its isoflavones. KEY WORDS: * lipoproteins * LDL oxidation * artery function * atherosclerosis

Previously our laboratory has shown that the soy isoflavone, genistein, stimulates growth of human breast cancer (MCF-7) cells in vivo and in vitro. In this study, the dose-response analysis of genistein at the physiologically achievable concentration range between 125 and 1,000 [micro]g/g in the diet was conducted in ovariectomized athymic nude mice implanted with MCF-7 cells. We hypothesized that genistein at this concentration range can stimulate dose-dependently the breast tumor growth, cell proliferation and an estrogen-responsive pS2 gene induction. Tumor size and body weight were monitored weekly. At completion of the study, we analyzed cellular proliferation of tumors using incorporation of BrdU, pS2 expression of tumors using a Northern blot analysis and total genistein level in plasma using liquid chromatography-isotope dilution mass spectrometry (LC-ES/MS). Dietary genistein (250 [micro]g/g) increased tumor size in a dose-dependent manner [8.4x the negative control (NC) group in the 250 [micro]g/g group, 12.0x in the 500 [micro]g/g group, 20.2x in the 1,000 [micro]g/g group and 23.2x in the positive control (PC) group]. The percentage of proliferating cells was significantly increased by genistein at and above 250 [micro]g/g (5.3x the NC group in the 250 [micro]g/g, 5.6x in the 500 [micro]g/g, 5.0x in the 1,000 [micro]g/g and 4.8x in the PC group). Expression of pS2 mRNA was also significantly increased with increasing dietary genistein levels (11.25x the NC group in the 500 [micro]g/g group and 15.84x in the 1,000 [micro]g/g group). Total plasma genistein concentrations were between 0.39 and 3.36 [micro]mol/L in mice fed between 125 and 1,000 [micro]g/g genistein. In conclusion, dietary treatment with genistein at physiological concentrations produces blood levels of genistein sufficient to stimulate estrogenic effects, such as breast tumor growth, cellular proliferation and pS2 expression in athymic mice in a dose-responsive manner similar to that seen in vitro. J. Nutr. 131: 2957-2962, 2001. KEY WORDS: * genistein * MCF-7 * athymicnudemouse * pS2 * BrdU

The development of a method for enriching soy protein concentrate with genistein, using the hydrocolloids alginate, pectin, carrageenan and xanthan gum, is described.

A new study investigates the genistin and genistein contents of soybean varieties and evaluates three basic soy protein concentrate production methods.

A new study investigates the effectiveness of beta-glucosidase in hydrolyzing genistin to form genistein in soy protein.

Glycitein metabolism was compared with other isoflavones to begin to understand the effect of this compound. Total isoflavones of 4.5 [micro]mol/kg body weight from soymilk (high in genistein and daidzein) and soygerm (high in daidzein and glycitein) was fed to seven women and seven men. To minimize interindividual variation, only subjects with moderate fecal isoflavone degradation rates (half-lives of daidzein and genistein were 15.7 and 8.9 h, respectively) were included. The average 48-h urinary excretion of glycitein, daidzein and genistein was [approximately]55, 46 and 29% of the dose ingested, respectively, which was significantly different from each other in men and women (P < 0.001). Plasma isoflavone concentrations at 6 and 24 h after soymilk feeding paralleled relative amounts of isoflavones in soymilk (genistein > daidzein > glycitein) (P < 0.05) in men and women, but plasma isoflavone concentrations after soygerm feeding did not parallel soygerm isoflavone concentrations in women because genistein and glycitein did not differ from each other at 6 h after feeding. Six hours after soygerm dosing, plasma isoflavone concentrations paralleled soygerm isoflavone levels in men. Based on plasma isoflavone concentrations at 6 h after dosing, the bioavailabilities of daidzein and genistein were similar in men and women. At the high glycitein dose (soygerm), plasma concentration at 24 h after dosing suggested a modest gender difference in glycitein bioavailability. Key Words: fecal isoflavone degradation; glycitein; humans; isoflavones; urinary disposition

We investigated the effect of dietary supplementation with isoflavones on pulmonary metastasis of B16BL6 murine melanoma cells in C57BL/6 mice. Mice were fed a basal AIN-93G diet or the basal diet supplemented with the isoflavones genistein and daidzein at 113 [micro]mol/kg, 225 [micro]mol/kg, 450 [micro]mol/kg, or 900 [micro]mol/kg for 2 wk before and after the intravenous injection of 0.5 x [10.sup.5] melanoma cells. At necropsy, the number and size of tumors that formed in the lungs were determined. The number of mice that had > 15 lung tumors was 17 in the control group, and 16, 15, 13, and 10 in the groups fed isoflavones at 113 [micro]mol/kg, 225 [micro]mol/kg, 450 [micro]mol/kg and 900 [micro]mol/kg, respectively. The latter two were significantly different from the control (P [less than or equal to] 0.05). The median number of tumors in the control group was 67, and those in the isoflavone-supplemented groups were 57, 33, 32, and 17, respectively. The last was significantly different from the control (P[less than or equal to] 0.05). Dietary supplementation with isoflavones at 225 [micro]mol/kg, 450 [micro]mol/kg, and 900 [micro]mol/kg also significantly decreased tumor size (median cross-sectional area and volume) compared to the control values. We conclude that dietary supplementation with isoflavones reduces experimental metastasis of melanoma cells in mice. KEY WORDS: mice; genistein; daidzein; melanoma; metastasis

Since the early 1940s, scientists have examined the effect of soy protein on blood cholesterol concentrations. Although studies in animals have suggested that soy protein lowers blood cholesterol concentrations, similar studies in humans have yielded less consistent results. The presence or absence of the soybean isoflavone fraction may be a confounding factor. This fraction, consisting primarily of genistein, daidzein and glycetein, has been shown to have a hypocholesterolemic effect in animals and humans. Potential mechanisms by which soy protein and/or isoflavones induce lowering of blood cholesterol concentrations include thyroid status, bile acid balance and the estrogenic effects of genistein and daidzein. Some studies have suggested that isoflavones exhibit antioxidant properties and have favorable effects on arterial compliance. In addition to the aforementioned potential beneficial effects, the increased consumption of products containing soy protein may displace foods relatively high in saturated fat and cholesterol from the diet and hence have an indirect blood cholesterol-lowering effect. KEY WORDS: * soybean * soy protein * isoflavones * phytoestrogens * cholesterol * LDL * coronary heart disease * genistein * daidzein * glycetein

The effects of consuming a soy protein isolate beverage powder (60 g/d for 28 d) vs. a casein supplement was evaluated in 20 male subjects who were randomly allocated into the two groups. A dramatic rise in plasma isoflavone concentrations was observed after supplementation in the soy protein group, the levels reaching 907 [+ or -] 245 nmol/L for genistein (a 110-fold increase) and 498 [+ or -] 102 nmol/L for daidzein (a 150-fold increase) as measured by isotope dilution gas chromatography - mass spectrometry. These concentrations are higher than previously reported for the plasma of Japanese subjects consuming a traditional diet (276 nmol/L and 107 nmol/L, respectively). No significant differences in collagen- or 9, 11-dideoxy-11[Alpha], 9[Alpha]-epoxymethanoprostaglandin [F.sub.2[Alpha]] (U46619)-induced platelet aggregation were observed in platelet-rich plasma from the two groups; the increase in plasma isoflavonoids from soy protein supplementation is not sufficient to significantly inhibit platelet aggregation ex vivo. Similarly, plasma total and HDL-cholesterol were not affected by protein supplementation, possibly because the men were normocholesterolemic at entry. Analysis of plasma phospholipid polyunsaturated fatty acid composition showed no differences between soy protein and casein supplementation. Previous investigations reported a significant alteration in fatty acid status in animals fed soy protein relative to those fed casein. The present studies indicate that although soy protein supplementation to a typical Western diet can increase plasma concentrations of isoflavones, this may not necessarily be sufficient to counter heart disease risk factors such as high plasma cholesterol and platelet aggregation. J. Nutr. 126: 2000-2006, 1996. INDEXING KEY WORDS: humans; soy protein; isoflavones; platelet; plasma cholesterol

Soybean isoflavones are proposed to be anticarcinogenic, but their effective doses have not been established. To study the bioavailability of soybean isoflavones for humans, 12 young adult women received single doses of 0.7, 1.3 and 2.0 mg isoflavones/kg body wt in soybean milk as part of a liquid diet. Plasma, urine and fecal isoflavones were measured by reverse-phase HPLC. Average 24-h urinary recoveries of daidzein and genistein were approximately 21% and 9%, respectively, at all three doses. Urinary recovery of daidzein was significantly greater than that of genistein (P < 0.001). Total fecal excretion of isoflavones was only 1-2% of the ingested amount. Plasma total isoflavone concentration was significantly increased to 4.4 + or - 2.5 micromol/L at 6.5 h after a dose of 2.0 mg/kg. The plasma concentrations of daidzein and genistein were approximately equal. Twenty-four hours after dosing, both plasma and urine isoflavone concentrations were nearly nil. Although soybean milk isoflavones seem to be 85% degraded in the intestine, the bioavailability, especially of daidzein, may be sufficient to exert some health-protective effects.

A comparative study of the effects of three different soaking solutions containing varying amounts of NaHCO3 on controlling the production of volatile organic compounds and nonvolatile isoflavone aglucones, believed to cause off-flavoring in soymilk is presented. Soybean samples were soaked for 6 hours in 50 degrees Celsius of water, in 50 degrees Celsius of a solution that contained .25% NaHCO3 and boiled for 30 minutes in the same concentrated solution. Results indicate that boiling soybeans in .25% NaHCO3 solution prevented the formation of volatile organic compounds, thus eliminating soymilk off-flavor.