Increase in Bone Calcification in Young Rats Fed Breads Highly Fortified with Calcium

Breads were prepared with flour fortified with calcium (Ca) at four levels: 211 (U.S. enrichment standard), 446, 924, and 1,412 mg/100 g of flour. Corresponding diets prepared with these breads and fed to growing rats for four weeks provided 25 (diet A), 50 (diet B), 100 (diet C), and 150% (diet D) of their Ca requirement. After four weeks, the Ca content of the femurs of these rats had increased significantly as Ca in the diet increased up to 100% of requirement but not beyond. The increase in femur strength was significant only between diet A and diet B. Apparent Ca absorption increased as Ca in the diet increased, but Ca absorbed from diet D was not retained any better than that absorbed from diet C. Overall, the data suggested that Ca in highly fortified breads was well absorbed and retained, and that the rats' Ca status early in life was greatly improved. Flour fortified with Ca up to the 924-mg level (4.4× the mandated enrichment level) had no adverse effect on bread quality. These breads can be labeled a “good source of ” or “high in” Ca.     

Soy processing affects metabolism and disposition of dietary isoflavones in ovariectomized BALB/c mice

Soy foods and nutritional supplements are widely consumed for potential health benefits. It was previously shown that isoflavone-supplemented diets, which contained equal genistein equivalents, differentially stimulated mammary tumor growth in athymic mice based on the degree of processing. This paper reports plasma pharmacokinetic analysis and metabolite identification using the parental mouse strain fed the same diets, which contained genistin, mixed isoflavones, Novasoy, soy molasses, or soy flour plus mixed isoflavones. Whereas the degree of soy processing did affect several parameters reflecting isoflavone bioavailability and gut microflora metabolism of daidzein to equol, stimulation of tumor growth correlated significantly with only the plasma concentration of aglycon genistein produced by the diets. This conclusion is consistent with the known estrogen agonist activity of genistein aglycon on mammary tumor growth. Conversely, plasma equol concentration was inversely correlated with the degree of soy processing. Although antagonism of genistein-stimulated tumor growth by equol could explain this result, the very low concentration of aglycon equol in plasma (12-fold lower relative to genistein) is inconsistent with any effect. These findings underscore the importance of food processing, which can remove non-nutritive components from soy, on the pharmacokinetics and pharmacodynamics of isoflavones. Such changes in diet composition affect circulating, and presumably target tissue, concentrations of genistein aglycon, which initiates estrogen receptor-mediated processes required for the stimulation of tumor growth in a mouse model for postmenopausal breast cancer.     

Isoflavone glycitein diminished plasma cholesterol in female golden Syrian hamsters

The soybean isoflavones, daidzein, genistein, and glycitein, were hypothesized to act as cholesterol-lowering components, separate from soy protein. Pure synthetic daidzein, genistein, or glycitein (0.9 mmol/kg diet) or a casein-based control diet was fed to groups of 10 female Golden Syrian hamsters for 4 weeks. Hamsters fed glycitein had significantly lower plasma total (by 15%) and non-HDL (by 24%) cholesterol compared with those fed casein (P<0.05). Daidzein and genistein's effects on these lipids did not differ from the effects of either casein or glycitein. Plasma HDL cholesterol and triglyceride concentrations were not significantly affected by dietary treatments. The percentage of urinary recovery of the ingested dose of each isoflavone was glycitein>daidzein>genistein (33.2%, 4.6%, 2.2%, respectively), with the apparent absorption of glycitein significantly greater than that of the other isoflavones. These data suggest that glycitein's greater cholesterol-lowering effect was due to its greater bioavailability, as reflected in its urinary recovery compared with that of the other isoflavones.     

Isoflavones in soy-based foods consumed in Brazil: levels,distribution, and estimated intake

The isoflavone content and profile in processed soy-based products consumed in Brazil were determined by high-performance liquid chromatography and photodiode array detection of the intact isoflavones (naturally occurring aglycons, malonyl, acetyl, and beta-glycosides derivatives). Total isoflavone content varied significantly among products, from 2 to 100 mg/100 g (wet basis, expressed as aglycons), with the lowest content being found for soy-based enteral/oral diets and the highest found for textured soy proteins. For soy beverages isoflavone content varied from 12 to 83 mg/L. Soy sauce, miso, and tofu had isoflavone contents of 5.7 mg/L, 20 mg/100 g, and 7 mg/100 g, respectively. The beta-glycosides were the predominant form of the isoflavones in the products analyzed, except for miso, shoyu, and "Diet Shake" in which the aglycons were present in the highest proportions. On the basis of these data, the daily intake of isoflavone from soy products was estimated: the highest values were found for infants fed soy-based formulas, from 1.6 to 6.6 mg/kg of body weight.     

Dietary fibers from mushroom sclerotia. 4. In vivo mineral absorption using ovariectomized rat model

The effect of three novel dietary fibers (DFs) prepared from mushroom sclerotia, namely, Pleurotus tuber-regium, Polyporus rhinocerus, and Wolfiporia cocos, on calcium and magnesium absorption was evaluated in ovariectomized (OVX) rats fed with sclerotial DF based and low Ca (0.3%) diets for 14 days. The animals in the W. cocos DF diet group possessed significantly (p < 0.05) higher levels of cecal total short-chain fatty acids (204 mumol/g of cecal content) and had an acidic pH (5.88) in their cecum when compared with those of the cellulose control group. Such an acidic environment was found to promote the ionization of the unabsorbed Ca and Mg in their cecum, which in turn significantly (p < 0.05) increased the concentrations of cecal soluble Ca (2.56-fold) and Mg (1.22-fold). Besides, the apparent Ca and Mg absorptions of the W. cocos DF group were also significantly (p < 0.05) enhanced (Ca, 16.5%; Mg, 15.3%) together with significantly (p < 0.05) higher serum Ca (3.61 mmol/L) and Mg (1.07 mmol/L) levels when compared with those of the cellulose control group. These data suggest that ingestion of W. cocos DF could improve the overall Ca and Mg absorptions of the OVX rats fed a low Ca diet. The potential use of sclerotial DFs as a functional food ingredient for enhancing mineral absorption is also discussed.     

Isoflavone conjugates are underestimated in tissues using enzymatic hydrolysis

Many health effects of soy foods are attributed to isoflavones. Isoflavones upon absorption present as free form, glucuronide, and sulfate conjugates in blood, urine, and bile. Little is known about the molecular forms and the relative concentrations of soy isoflavones in target organs. Acid hydrolysis or enzymatic hydrolysis (glucuronidases and sulfatases) was used to study isoflavone contents in the heart, brain, epididymis, fat, lung, testis, liver, pituitary gland, prostate gland, mammary glands, uterus, and kidney from rats fed diets made with soy protein isolate. The heart had the lowest isoflavone contents (undetectable), and the kidney had the highest (1.8 +/- 0.6 nmol/g total genistein; 3.0 +/- 1.1 nmol/g total daidzein). Acid hydrolysis released 20-60% more aglycon in tissues than enzymatic digestion (p < 0.05), and both hydrolysis methods gave the same level of isoflavones in serum. Approximately 28-44% of the total isoflavone content within the liver was unconjugated aglycon, and the remainder was conjugated mainly as glucuronide. The subcellular distribution of total isoflavones was 55-60% cytosolic and 13-16% in each of the nuclear, mitochondrial, and microsomal fractions. These results demonstrated that (1) soy isoflavones distribute in a wide variety of tissues as aglycon and conjugates and (2) the concentrations of isoflavone aglycons, which are thought to be the bioactive molecules, are in the 0.2-0.25 nmol/g range, far below the concentrations required for most in vitro effects of genistein or daidzein.     

Acute and chronic effects of honey and its carbohydrate constituents on calcium absorption in rats

The effects of honey and its carbohydrate constituents (glucose, fructose, and raffinose) on calcium absorption in rats were investigated in acute and chronic feeding studies. In the acute study, rats ( n = 120) were gavaged with an oral solution consisting of (a) 10 microCi (45)Ca, (b) 25 mg of calcium as calcium acetate, and (c) one of the following: 0 mg of honey (control), or 200, 500, or 800 mg of honey, a glucose-fructose mixture, 10.75 mg of raffinose, or 200 mg of raffinose. Another group received (45)Ca intraperitoneally. Femurs were collected 2 days later and analyzed for (45)Ca content. Rats given 500 and 800 mg of honey showed 25.5 and 33.6% increases in calcium absorption ( P<0.05), respectively, over the control group. Groups given the glucose-fructose mixture or 200 mg of raffinose had a significantly higher increase in calcium absorption than the control group (17.1 and 25.6%, respectively). In the chronic study, rats (n=96) were fed for 8 weeks with either 0% honey (control), 5% honey, 10% honey, or a glucose-fructose-raffinose (GFR) mixture. Femurs of GFR-fed rats had significantly lower calcium content, (45)Ca absorption, width, and BMD (at distal region) than control rats. Groups fed honey did not show the negative effects of GFR on bone, but had no advantage over the control group. No significant differences were observed in femur length, density, strength, or BMC among any treatment group compared to the control group. These results indicate that although a positive dose-response effect of honey and its carbohydrate constituents on calcium absorption was observed in the acute study, this effect disappeared upon long-term feeding in rats, implying adaptation had occurred.     

Ingestion of water-soluble soybean fiber prevents osteopenia and hypercholesterolemia induced by ovariectomy in rats

This study examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on intestinal calcium (Ca) absorption, bone mineral content, and serum total cholesterol levels using female Sprague-Dawley rats (5 weeks old) with or without ovariectomy (OVX). The rats in each group were fed a WSSF (50 g/kg of diet) or WSSF-free diet for 4 weeks. Ca absorption was higher in OVX rats fed the WSSF diet than in OVX rats fed the WSSF-free diet. Femoral Ca content in both sham and OVX rats fed the WSSF diet was higher than that in rats fed the WSSF-free diet. The serum total cholesterol levels were elevated after OVX compared with that in the sham rats, and this elevation was prevented by the WSSF diet. In conclusion, ingestion of WSSF prevented osteopenia and hypercholesterolemia induced by ovariectomy in rats.     

Utilization of Calcium in Breads Highly Fortified with Calcium as Calcium Carbonate or as Dairy Calcium

White pan breads were prepared with flour highly fortified with calcium (Ca), using Ca carbonate (Ca, 38.8%) or a high Ca whey powder (Ca, 5.6%) as the Ca source; bread was also prepared using Ca carbonate plus lactose. Ca was added to flour at 924 mg/100 g of flour, a level 4.4 times higher than specified under the U.S. enrichment standards. Breads were dried and finely ground to prepare test diets (Ca, 0.5%) which were then fed to growing rats for four weeks (growth phase) or eight weeks (approaching maturity). At either interval, femur ash content, femur Ca content, femur strength, or Ca absorption values did not differ significantly among groups fed breads fortified either with Ca carbonate, Ca carbonate + lactose, or whey. Thus, breads can be highly fortified with Ca carbonate to be labeled as “high” in Ca, and this Ca may be as well absorbed and utilized as dairy Ca.     

Regulative actions of dietary soy isoflavone on biological antioxidative system and lipid metabolism in rats

Male Sprague-Dawley rats, 4 weeks of age, were fed purified diets either with or without 0.2% soy isoflavones rich powder for 5 weeks to elucidate their direct functions such as antioxidative action and regulation of lipid metabolism. Dietary soy isoflavones decreased serum lipid peroxide level in rats. Levels of liver and serum alpha-tocopherol were higher in the rats fed isoflavone than in those fed isoflavones-free diet. Thus, dietary soy isoflavones exhibited mild antioxidative function in this animal experiment. Isoflavone metabolites from diet may act as scavengers of reactive oxygen species. Dietary soy isoflavones lowered hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity, although liver cholesterol level was not modulated. However, the levels of serum cholesterol and triglyceride decreased by consumption of soy isoflavones. Therefore, dietary soy isoflavones may exhibit hypocholesterolemic and hypolipidemic functions. Moreover, dietary soy isoflavones lowered hepatic Delta6 desaturase activity. Reflecting this observation, Delta6 desaturation indices ((18:2(n = 6) + 18:3(n = 6))/20:4(n = 6)) of tissue lipids tended to be lower in rats fed isoflavones than in those fed isoflavones-free diet. This action may contribute to the prevention of inflammatory response by imbalance of eicosanoids. These observations suggest that the positive intake of soy isoflavones may reduce the risk of some cardiovasucular diseases through their radical scavenging function and hypocholesterolemic action.     

Phytate phosphorus hydrolysis as influenced by dietary calcium and micro-mineral source in broiler diets

Phytate phosphorus (PP) hydrolysis by a 3-phytase was studied in vitro at pH 2.5 and 6.5 with either 0, 1.0, 4.0, or 9.0 g of Ca/kg diet, or 0, 1.0, 5.0, 7.5, or 10.0 g/kg diet of micro-mineral premix added as inorganic (IMM) or an equivalent level as micro-mineral-amino acid complexes (MAAC). Adding Ca or micro-minerals reduced (P < 0.05) PP hydrolysis at both pHs; however, the effect was greater at pH 6.5. An in vivo experiment was conducted in which broilers were fed one of six diets for 30 h. The experimental design was a factorial of three micro-mineral forms (0 added, IMM, and MAAC) and two Ca levels (0 or 5 g/kg). Adding Ca reduced (P < 0.05) PP disappearance and increased Ca apparent absorption. No micro-minerals effect (P > 0.05) was seen. Therefore, in poultry diets, it is Ca that inhibits PP hydrolysis and decreases P availability.     

Variation in isoflavone of soybean cultivars with location and storage duration

Fifteen soybean [Glycine max (L.) Merrill] cultivars were grown in Seoul, Suwon, and Kyongsan, Korea, in 1998, 1999, and 2000, and their isoflavone contents were assessed. After harvest, the beans were stored for 3 years at room temperature. Soybean isoflavones were analyzed using high-performance liquid chromatography (HPLC) within each crop year and after storage. Total isoflavone contents ranged from 188.4 to 685.6 mg 100 g(-1) in 1998, from 218.8 to 948.9 mg 100 g(-1) in 1999, and from 293.1 to 483.0 mg 100 g(-1) in 2000. The year x variety, and year x location x variety interactions were significantly different in 1998, the year x location, year x variety, and year x location x variety interactions were significantly different in 1999, and the year x variety interaction was significantly different in 2000 for total and individual isoflavone contents. Total isoflavone contents of soybeans stored for 1 year were only slightly higher than those of soybeans stored for 2 or 3 years. However, the concentrations of individual isoflavones, especially 6' '-O-malonyldaidzin and 6' '-O-malonylgenistin, decreased markedly in soybeans stored for 2 or 3 years. These data suggest that it may be feasible to improve soybean cultivars with higher antioxidative substances.     

Effects of dose and glycosylation on the transfer of genistein into the eggs of the Japanese quail (Coturnix japonica)

Soy isoflavones have been associated with several beneficial effects of soy in human diets. However, most soy is consumed by livestock in the Western countries. It is possible that isoflavones could be transferred and/or accumulated into animal products, which could become additional sources of dietary isoflavones for humans. Our objectives were to determine whether dietary isoflavone genistein could be transferred and/or accumulated into the eggs of Japanese quail (Coturnix japonica) and how the supplementation dosage and glycosylation of the isoflavone would affect this transfer. Adult reproductive female Japanese quail were randomly assigned to treatment groups that received encapsulated 50 or 100 mg genistein or 80 mg genistin per day (four quail per treatment) for 5 days. A control group (two quail) received placebo capsules. Eggs were collected prior to treatment and then daily for 15 days. The egg, separated into yolk and white, and pulverized quail diet were extracted in 80% methanol for 2 h and either centrifuged or filtered before evaporation of the solvent. The extracts were redissolved in 16% acetonitrile for high-performance liquid chromatography (HPLC) analyses. Genistein and genistein metabolites were detected in the egg yolks of treated quail. Trace concentrations of genistein were detected in the control group, due to the presence of genistein derivatives in the diet. Neither genistein nor its metabolites were found in egg white. Levels of genistein in the eggs increased significantly from the 3rd day of supplementation and reached the maximum about 2 days after the supplementation stopped. The higher dose of genistein supplementation resulted in higher genistein concentrations in egg yolks. Glycosylation decreased the transfer and accumulation of genistein into the egg yolks.     

Determination of 15 isoflavone isomers in soy foods and supplements by high-performance liquid chromatography

Soy isoflavone is the generic name for the isoflavones found in soy. We determined the concentrations of 15 soy isoflavone species, including 3 succinyl glucosides, in 22 soy foods and isoflavone supplements by high-performance liquid chromatography (HPLC). The total isoflavone contents in 14 soy foods and 8 supplements ranged from 45 to 735 μg/g and from 1,304 to 90,224 μg/g, respectively. Higher amounts of succinyl glucosides were detected in natto, a typical fermented soy product in Japan; these ranged from 30 to 80 μg/g and comprised 4.1-10.9% of the total isoflavone content. In soy powder, 59 μg/g of succinyl glucosides were detected, equivalent to 4.6% of the total isoflavone content. These data suggest that the total isoflavone contents may be underestimated in the previous studies that have not included succinyl glucosides, especially for Bacillus subtilis -fermented soy food products.     

Comparison of isoflavone concentrations in soybean (Glycine max (L.) Merrill) sprouts grown under two different light conditions

We determined and compared the composition and content of isoflavones in the cotyledon, hypocotyl, and root of 17 soybean sprout varieties grown under dark and light conditions. The total average isoflavone concentrations in 17 soybean sprout varieties were 2167 microg g(-1) (green sprout) and 2538 microg g(-1) (yellow sprout) in cotyledons, 1169 microg g(-1) (green sprout) and 1132 microg g(-1) (yellow sprout) in hypocotyls, and 2399 microg g(-1) (green sprout) and 2852 microg g(-1) (yellow sprout) in roots. There were no significant differences in total isoflavone concentrations between the green and yellow sprouts. However, significant differences in total isoflavone amounts were observed among the three organs, with roots exhibiting the highest total isoflavone concentrations followed by cotyledons and hypocotyls. Total daidzin concentrations of green (775 microg g(-1)) and yellow (897 microg g(-1)) sprouts increased to more than 4 times that in seeds (187 microg g(-1)). Yellow sprouts contained the highest (1122 microg g(-1)) total genistin concentrations, and green (155 microg g(-1)) and yellow (155 microg g(-1)) sprouts had more total glycitin concentrations than seeds. In cotyledons of green and yellow sprouts, genistin, daidzen, and glycitin constituted more than 67%, more than 28%, and less than 4% of the total isoflavone contents, respectively. In hypocotyls, total daidzin represented more than 45% of the total isoflavones, and total glycitin was higher than in cotyledons and roots. Malonylglycoside concentrations were highest in cotyledons, whereas glycoside concentrations were highest in hypocotyls and roots. The high accumulation of isoflavones in roots is consistent with isoflavones serving as signal molecules in the induction of microbial genes involved in soybean (Glycine max) nodulation.     

Isoflavone content and its potential contribution to the antihypertensive activity in soybean Angiotensin I converting enzyme inhibitory peptides

A soybean angiotensin I converting enzyme (ACE) inhibitory peptide fraction was reported to have antihypertensive activity in a rat study. The purpose of the present study was to examine if the presence of isoflavones in the soybean ACE inhibitory peptide fraction may contribute to the blood-pressure-lowering property. The isoflavone concentration in soybean samples was analyzed on a C 18 reverse-phase column using a two-step gradient solvent system. Producing soybean hydrolysate led to a nearly 40% loss of isoflavones compared with the original soybean flour, but the isoflavone composition did not change and the dominant isoflavone chemicals remained as 6'-O-malonylgenistin and 6'-O-malonyldaidzin. Ion exchange chromatography affected significantly both the content and the composition of the isoflavones. The dominant isoflavones in the ion-exchanged fraction were aglycones and nonacylated isoflavones, accounting for 95.8% of the total amount of 987.7 microg/g. It was calculated that the isoflavone content in the soybean ACE inhibitory peptide fraction was 25 times less than the minimal effective isoflavone dose reported. In vitro study also showed that adding isoflavones into both soybean flour hydrolysate and soybean ACE inhibitory peptide samples to a concentration of as high as 31.5% (w/w) did not affect ACE inhibitory activity (IC 50 values). The findings along with previously published results indicated that the contribution of isoflavones in soybean ACE inhibitory peptide fraction to the blood-pressure-lowering property in a short-term feeding study might be negligible.     

Isoflavone aglycon and glucoconjugate content of high- and low-soy U.K. foods used in nutritional studies

The isoflavone aglycon and glucoconjugate content of commercially prepared and "home-prepared" high- and low-soy foods selected for use in an on-going nutritional study were measured by LC-MS. The daidzin, daidzein, 6"-O-malonyldaidzin, 6"-O-acetyldaidzin, genistein, genistin, 6"-O-malonylgenistin, 6"-O-acetylgenistin, glycitin, glycitein, 6"-O-malonylglycitin, and 6"-O-acetylglycitin content are expressed in terms of individual isoflavones, total isoflavone equivalents, and milligrams of isoflavones per portion served. Soybeans (774 mg x kg(-1) total isoflavones) and soybean-containing foods had the highest isoflavone content of the foods examined. The low-soy foods all contained very low concentrations (<8 mg x kg(-1) total isoflavones) of the isoflavone aglycons and glucoconjugates. High- and low-soy 11 day rotating menus were constructed from the analyzed foods to deliver 100.0 and 0.5 mg of isoflavones per day, respectively.     

Health-promoting effects of a dietary fiber concentrate from the soybean byproduct okara in rats

Okara (a byproduct of the soy milk industry) is rich in proteins (24.5-37.5 g/100 g of dry matter (dm)), lipids (9.3-22.3 g/100 g of dm), and dietary fiber (DF) (14.5-55.4 g/100 g of dm). It also contains isoflavones (0.14 g/100 g of dm). In the present study we fed female healthy Wistar rats either a standard rat diet or a supplemented 10% DF-rich okara (DFRO) diet for 4 weeks, and then we assessed several health parameters in the serum and the cecum compartments. In comparison to the control group, rats fed DFRO showed a significant decrease in weight gain (5.00 +/- 1.22 g vs 2.00 +/- 1.46 g, P < 0.03, during week 4) and in total cholesterol (65 +/- 8 mg/dL vs 51 +/- 5 mg/dL, P < 0.05) and a significantly increased antioxidant status (36.71 +/- 15.31 micromol of Trolox equivalents (TEs)/g vs 69.75 +/- 16.11 micromol of TEs/g, P < 0.0003) and butyrogenic effect (39.37%, P < 0.003) in the cecum. In addition, a significant enhancement in the apparent absorption (41.89 +/- 1.64% vs 47.02 +/- 2.51%, P < 0.004) and in the true retention (41.62 +/- 1.60% vs 46.68 +/- 2.55%, P < 0.005) of calcium was appreciated. In summary, these findings show for the first time that a concentrate DF from a soybean byproduct protects the gut environment in terms of antioxidant status and prebiotic effect. These results may highlight the development of an innovative soybean byproduct rich in DF which could be useful as a functional ingredient with health-promoting attributes.     

Retention and changes of soy isoflavones and carotenoids in immature soybean seeds (Edamame) during processing

Isoflavones and carotenoids in four experimental genotypes and Hutcheson cultivar soybeans were evaluated as a function of processing treatments and maturity. Total isoflavone and carotenoid contents were affected by genotypes and maturity stages (p < 0.0001). Total isoflavones ranged from 472 microg/g (in NTCPR93-40) to 2280 microg/g (in Hutcheson). Lutein contents ranged from 895 (in NTCPR93-286) to 2119 (in Honey Brown), and beta-carotene ranged from 291 (in Hutcheson) to 491 (in NICPR92-40) microg/100 g. Mean total isoflavone retention percentages in immature Hutcheson soybeans were 46% (boiling), 53% (freezing), and 40% (freeze-drying). Mean retentions of lutein and beta-carotene, respectively, were 92 and 73% in frozen, 62 and 62% in boiled, and 34 and 27% in freeze-dried soybeans. Boiling caused a substantial increase in daidzin, genistin, and genistein. The results show that post-harvest changes in total isoflavones and carotenoids in soybeans are influenced by processing methods, but genotype has an effect on isoflavone and carotenoid profiles during seed development.     

Isolation of radiolabeled isoflavones from kudzu (Pueraria lobata) root cultures

Isoflavones have potential for preventing and treating several chronic health conditions, such as osteoporosis, cardiovascular disease, and cancer. In this study, radiolabeled isoflavones were recovered from kudzu (Pueraria lobata) root cultures after incubation with uniformly labeled (14)C-sucrose in the culture medium for 21 days. Approximately 19% of administered label was recovered in the isoflavone-rich dried extracts of kudzu root cultures (90.2 microCi/g or 3.3 MBq/g extract). HPLC-PDA analysis revealed the predominant isoflavones isolated from kudzu root cultures to be puerarin, daidzin, and malonyl-daidzin. The average concentration of the major isoflavone puerarin in kudzu root cultures was 33.6 mg/g extract, with a specific activity of 63.5 microCi/g (2.3 MBq/g). The isolated isoflavones were sufficiently (14)C-labeled to permit utilization for subsequent in vivo metabolic tracking studies.