大豆异黄酮对老龄雌性大鼠血清性激素水平影响

目的 观察大豆异黄酮对老龄雌性大鼠卵巢及血清中主要性激素水平影响。方法 选用20月龄老龄雌性大鼠50只, 按体重随机分为5组, 每组10只, 分别为空白对照组, 大豆异黄酮低、中、高剂量组(100、200、300 mg/kg)、雌激素组(己烯雌酚0.6 mg/kg), 连续给予8周。采用酶联免疫吸附实验测定各组大鼠卵巢及血清中雌二醇、孕酮、睾酮、黄体生成素(LH)、促卵泡生成素(FSH)、性激素结合球蛋白(SHBG)水平。结果 与对照组比较, 高剂量大豆异黄酮组大鼠卵巢/体比(0.031±0.008)明显降低(P<0.05), 血清中雌二醇含量[(5.177±0.453)μg/L]明显升高, LH含量[(3.225±0.405)ng/L]、FSH含量[(1.536±0.186)IU/L]降低(P<0.05);与对照组比较, 大豆异黄酮组大鼠血清中孕酮、睾酮、SHBG水平无明显变化(P>0.05)。结论 大豆异黄酮可通过调节老龄雌性大鼠血清中雌二醇、LH、FSH水平缓解卵巢功能衰退。     

Dietary soy protein isolate and isoflavones modulate hepatic thyroid hormone receptors in rats

Thyroid hormone receptors (TRs) are regulators of many genes involved in cholesterol and lipid metabolism. The purpose of this study was to examine the effect of soy protein isolate (SPI) and isoflavones on hepatic TRs in rats. In Expt. 1, Sprague-Dawley rats were fed diets containing either casein or alcohol-washed SPI with or without isoflavone supplementation (5-1250 mg/kg diet) for 70, 190, and 310 d. The offspring (F1) were fed the same diets as their parents (F0). In Expt. 2, Sprague-Dawley rats were fed diets containing casein or casein plus isoflavones (50-400 mg/kg diet) for 120 d. The mRNA and protein contents of the hepatic TRs were measured by semiquantitative RT-PCR and Western blot, respectively. TRalpha1, TRalpha2, and TRbeta2 contents were not affected by SPI. However, the content of the 52-kDa TRbeta1 protein, the major isoform present in the liver, was markedly increased by dietary SPI in both sexes of F0 and F1 compared with casein. The supplemental isoflavones had no effect on TRbeta1, whereas the high doses of isoflavones (250 and 1250 mg/kg diet) reduced the hepatic TRalpha1 protein content in F1 male rats on d 28. SPI had no effect on total T3 and T4 levels. However, higher dose of supplemental isoflavones markedly increased T4 level in female rats. Overall, this study demonstrates for the first time that SPI upregulates hepatic TRbeta1 expression, and that isoflavones reduce the hepatic TRalpha1 level in young male rats. The SPI-induced TRbeta1 may play a role in mediating the hypocholesterolemic and lipid-lowering actions of soy protein.     

毒死蜱对雄性大鼠生精功能及相关激素水平影响

目的 探讨毒死蜱对雄性大鼠生精功能和血清激素水平的影响.方法 选择21 d龄无特定病原体级雄性Wister大鼠随机分成3个实验组和1个对照组,每组10只.实验组灌胃给予毒死蜱,剂量为2.7、5.4、12.8 mg·kg-1·d-1;对照组给予等量蒸馏水稀释的吐温80溶液.染毒90d后,测定各组大鼠睾丸、附睾和前列腺-精囊腺等脏器系数、检测附睾尾精子数量、精子活动率和精子崎形率以及血清中性激素水平.结果 高、中剂量组精子数量减少、精子畸形率升高、精子活力显著降低(P<0.05).高、中剂量组血清睾49 (T)水平降低,促卵泡刺激素(FSH)升高(P<0.05).不同组别血清中黄体生成素(LH)及雌二醇(E2)水平比较,差异无统计学意义(P>0.05).结论　毒死蜱对雄性大鼠有明显的生殖毒性,可影响雄性大鼠生精功能和血清中性激素水平.     

锰对雄性小鼠血清性激素水平的影响

目的 探讨锰暴露对雄性小鼠血清性激素分泌的影响。 方法 选用健康雄性昆明小鼠48只,随机分为对照组和低、中、高染锰组。各组小鼠分别腹腔注射生理盐水、12.5、25.0、50.0 mg/kg MnCl₂,注射容量5 ml/kg,每天染毒1次,持续14 d,最后一天染毒24 h后处死小鼠,测量体重、睾丸和附睾的重量,腹主动脉采血,离心后取血清用酶联免疫试剂盒检测促性腺激素释放激素(gonadotropin-releasing hormone,GnRH)、卵泡刺激素(folide-stimulating hormone,FSH)、黄体生成素(luteinizing hormone,LH)和睾酮(testosterone,T)的水平。HE染色观察下丘脑神经元细胞组织形态的改变。 结果 与对照组相比,各染锰组小鼠体重、睾丸和附睾脏器系数差异无统计学意义(P>0.05),而高锰组血清中GnRH、FSH和LH含量显著升高至68.22 ng/L、11.43 U/L、2 055.82 pg/ml(P<0.05),T水平明显降低至81.25 nmol/L(P<0.05)。HE染色发现对照组可见结构清楚,排列规整,核膜清晰,染锰组逐渐形态紊乱,胞体皱缩,细胞周围间隙增大。 结论 锰暴露可引起雄性小鼠血清性激素分泌异常以及下丘脑组织形态受损,GnRH、FSH、LH明显升高,睾酮降低。     

The effect of nutritional factors on sex hormone levels in male twins

Dietary intake has been hypothesized as being associated with several hormonally related cancers including prostate, breast, ovarian, and endometrial cancer. Because diet may affect hormones directly, it is logical to examine the effects of dietary factors on hormone production and levels. Therefore, a set of 72 male MZ and 83 male DZ twin pairs was ascertained from the Utah birth certificates. A quantitative food frequency questionnaire was administered and blood samples were drawn for hormonal assays. Heritability estimates for hormonal levels were calculated indicating a range from no heritability for sex hormone binding globulin (SHBG), estrone, and testosterone glucuronide to 70% for androstanediol glucuronide and luteinizing hormone. To examine nutritional factors, the difference in hormone and SHBG levels between each MZ twin and his co-twin were correlated with the difference in nutrient intake. Weight and obesity were significantly correlated with plasma testosterone and follicle stimulating hormone. Fat intake showed a significant association with testosterone. Androstanediol glucuronide, a steroid that reflects tissue formation of dihydrotestosterone, was inversely correlated with caloric intake, theobromine and caffeine. Testosterone glucuronide exhibited significant correlations with calories and vitamin A. This study suggests that dietary intake affects plasma sex-steroid levels in men.     

镉接触工人体内血清性激素水平的变化

目的 探讨镉接触工人体内血清性激素水平的变化及其机制。方法 选取南方某冶炼厂镉接触工人及当地健康男性为调查对象,经空气采样测定各车间空气中镉的浓度,用原子吸收分光光度法测定尿镉,并经肌酐校正作为调查对象体内镉负荷的生物标记物;同时测定工人体内性激素水平,并进行镉接触的剂量－效应评定。结果 在控制年龄等混杂因素后,血清睾酮水平随镉接触水平的增高而呈升高趋势,其中尿镉为10．9－21．9μmol/mol肌酐及＞21．9μmol/mol肌酐组的睾酮水平分别为：13．00nmol／L和11．37nmol／L,与0．0－2．2μmol/mol肌酐组的9．31nmol／L比较,差异有显著性;电解车间及尿镉＞21．9μmol/mol肌酐组人的血清黄体生成素水平分别为4．11U／T和4．32U／L,显著同于对照组的2．52U／L和尿镉0．0－2．2μmol/mol肌酐组的2．64U／L。结论 镉接触能引起工人血清性激素水平的变化。     

Changes in male reproductive system and mineral metabolism induced by soy isoflavones administered to rats from prenatal life until sexual maturity

Objective

This study aimed to determine the influence of high-dose soy isoflavones (daidzein and genistein) administered from prenatal life to sexual maturity on testosterone and estradiol levels, testicular and epididymal morphology, the number of epididymal spermatozoa, and mineral metabolism in rats.

Methods

Pregnant Wistar rats received orally soy isoflavones, daidzein, and genistein at a dose of 200 mg/kg of body weight per day. After separating sucklings from their mothers, male rats received the same dose of isoflavones until reaching the age of sexual maturity, i.e., for 3 mo.

Results

In the isoflavone-treated group, statistically significant decreased concentrations of zinc (determined using atomic absorption spectrophotometry) in blood serum and increased concentrations in bone were observed. The isoflavones induced changes in the morphology of the seminiferous epithelium of rat testes. However, there were no significant changes in the number of spermatozoa in the epididymis. The levels of estradiol in serum and cauda epididymis homogenates of rats receiving phytoestrogens were significantly higher than in the control group. No differences were observed in testosterone concentrations in the serum of treated and control rats. The testosterone levels in the homogenates of the treated rat testes were significantly lower than in the control group.

Conclusion

The relatively mild effects of phytoestrogen administration on the morphology of testes and epididymides and the number of epididymal spermatozoa were observed despite the high dose used. The exposure of rats to genistein and daidzein during intrauterine life until sexual maturity influenced the mineral metabolism of the organism by significant decreases of Zn concentration in serum and increased Zn concentration in bones.     

Inhibitory effects of soy isoflavones on cardiovascular collagen accumulation in rats

Oxidative stress is a major cause of cardiovascular tissue fibrosis. We evaluated the effects of daily doses of soy isoflavones, genistein and daidzein on cardiovascular tissue fibrosis in Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rats and Long-Evans Tokushima Otsuka (LETO) non-diabetic rats as a severe or mild oxidative stress model, respectively. Glucose and lipid metabolisms did not improve with genistein or daidzein treatment. However, genistein decreased hydroxyproline concentrations in the heart. Hydroxyproline reductions as a result of genistein were mildly stronger than those of daidzein. Thus, genistein significantly suppressed the progression of myocardial fibrosis in LETO rats despite the insignificant changes in OLETF rats. Although a daily dosage of isoflavone was not sufficient to prevent tissue fibrosis under marked oxidative stress in the early stage of diabetes, isoflavones might promise significant clinical benefits by reducing oxidative stress in the heart during aging.     

1.1⁃二氨基⁃2,2⁃二硝基乙烯对雄性大鼠性激素水平的影响

为评价1,1-二氨基-2,2-二硝基乙烯(FOX-7)对雄性大鼠性激素水平的影响,将受试物采用3个剂量(199.1、99.6、49.8 mg/kg)染毒,同时设溶剂对照组(4%淀粉溶液)。将40只健康SPF级雄性SD大鼠随机分为4组,每组10只,每日固定时间采用经口灌胃方式染毒,染毒容量为1 ml/100 g,连续14 d。于第0天、第7天、第14天称量大鼠体重,禁食12 h后,于第15天对大鼠进行腹主动脉采血,使用ELISA试剂盒检测雌二醇(E2)、促卵泡素(FSH)、黄体生成素(LH)、睾酮(T)、促性腺激素释放激素(GnRH)含量。结果显示,与溶剂对照组比较,FOX-7高剂量组大鼠第7天和第14天体重显著下降(P0.05),性激素T、FSH、LH、E2和GnRH含量均显著降低(P0.05)。提示高剂量的FOX-7可能会引起雄性大鼠性激素水平紊乱,生殖系统损伤。     

Intake of soy foods and soy isoflavones by rural adult women in China

This study evaluated the intake of soy foods and soy isoflavones by rural adult women and potential determinant factors. Soy food consumption and information on age, education and medical history were collected on 1,188 subjects in Gansu Province and Hebei Province, China using a food frequency questionnaire to gather data on food intake over the past year. Weight and height were simultaneously measured. The results showed that 1139 (95.9%) rural women consumed soy foods in the past year. The average intake of soy foods and isoflavones was 38.7 +/- 58.2 (median = 23.5) g/d and 17.7 +/- 26.6 (median= 8.9) mg/d, respectively. Tofu accounted for the most contribution to their intake. The soy isoflavone intake ranged between 0-35 mg/day in 89.2% of subjects. Gansu women had higher intakes of soy foods and isoflavones than Henbei women (P< 0.05). Women aged 41-50 years consumed less soy foods and isoflavones than the 20-30-year olds and 31-40 year olds(P < 0.05). The intake of soy foods (P< 0.01) and isoflavones (P< 0.01) by women who experienced secondary education or above was significantly higher than illiterate women. Women without a medical history had a higher soy isoflavone intake than women with a medical history, but the difference was not statistically significant. These results suggest that the intake of soy isoflavones by Chinese rural adult women was much higher than women in Western countries. The distribution of intake was skewed to the right and varied among women in regard to region, age group and education level.     

Chemopreventive effects of soy protein and purified soy isoflavones on DMBA-induced mammary tumors in female Sprague-Dawley rats

There are conflicting reports on the effect of soy and its components on mammary carcinogenesis in adult female rats, mainly because of different rodent models that are used in chemoprevention studies. The present study was undertaken to compare the tumor-preventative effects of soy protein isolate (SPI) and two of its isoflavones in a "standard" model that had been used for the identification of many chemopreventive agents. Six groups of female Sprague-Dawley rats were provided with modified cornstarch AIN-76A diets supplemented as follows: no additional agents (control), purified genistein (200 mg/kg diet), purified daidzein (200 mg/kg diet), genistein + daidzein (100 mg/kg diet each), SPI containing normal levels of isoflavones (SPI-n), or SPI depleted of isoflavones (SPI-d). Mammary carcinomas were induced by 7,12-dimethylbenz[a]anthracene (DMBA) introduced 1 wk after the animals began consuming the experimental diets. At the end of the study (120 days after DMBA treatment), no significant differences were found among the six groups with respect to tumor incidence or survival, nor was there a significant reduction in tumor multiplicity in the genistein or genistein + daidzein group. However, there was a 32% reduction in tumor multiplicity in the daidzein and SPI-n groups relative to the control group (P < 0.05). The most effective diet was SPI-d, which produced a 50% reduction in tumor multiplicity relative to the control (P < 0.01). The difference between the SPI-d group and the daidzein or SPI-n group was not significant. Median tumor latency was increased from 53 days in the control group to 68 days in the daidzein group and to 72 days in the SPI-d group, but these differences were not statistically significant. These results show that daidzein and SPI (with normal or low levels of isoflavones) are effective inhibitors of DMBA-induced mammary tumors in adult rats.     

Fermented soy product supplemented with isoflavones affected fat depots in juvenile rats

OBJECTIVES: This study investigated the effects of soy product fermented by Enterococcus faecium and Lactobacillus jugurti supplemented with isoflavones on adipose tissue, blood lipid, and glucose levels on juvenile rats. METHODS: Rats were fed a cholesterol-enriched diet for 3 wk as a preliminary treatment to create hypercholesterolemia. They were then fed a chow diet (HC), a chow diet plus fermented soy product supplemented with isoflavones (HCFI), a chow diet plus placebo (HCP), or a chow diet plus placebo supplemented with isoflavones (HCPI), respectively, for an additional 3 wk. RESULTS: The beneficial effects of fermented soy product supplemented with isoflavones on epididymal (EPI) and retroperitoneal (RET) fat pads was likely due to isoflavones because adipocyte circumference (micrometers) in the HC group was significantly larger (EPI: 105.66 +/- 13.36; RET: 134.95 +/- 25.40) than that in the HCFI group (EPI: 93.17 +/- 12.80; RET: 108.62 +/- 15.50) and HCPI group (EPI: 93.06 +/- 15.10; RET: 112.34 +/- 18.21). The probiotic micro-organism accentuated the antilipogenic effect of isoflavones on RET (HCFI: 108.62 +/- 15.50 micrometers versus HCPI: 112.34 +/- 18.21 micrometers). Moreover, the fermented product increased glucose concentration similar to that in the chow group but did not change blood lipids. CONCLUSION: This product may offer new approaches to obesity prevention.     

Factors affecting the bioavailability of soy isoflavones in humans after ingestion of physiologically relevant levels from different soy foods

The precise role that isoflavones play in the health-related effects of soy foods, and their potential for adverse effects are controversial. This may be due in part to a lack of basic knowledge regarding their bioavailability and metabolism, particularly as it relates to the soy source. To date, there is little information concerning possible differences in the bioavailability of isoflavones derived from natural soy foods consumed at physiologically relevant intakes and whether age- or gender-related differences influence that bioavailability. In the current study of healthy adults [premenopausal (n = 21) and postmenopausal (n = 17) women and a group of men (n = 21)], we examined the effect of age, gender, and the food matrix on the bioavailability of isoflavones for both the aglycon and glucoside forms that are naturally present in 3 different soy foods, soy milk, textured vegetable protein, and tempeh. The study was designed as a random crossover trial so that all individuals received each of the 3 foods. The dose of isoflavones administered to each individual as a single bolus dose was 0.44 mg/kg body weight. Pharmacokinetic parameters were normalized to mg of each isoflavone ingested per kilogram body weight to account for differences in daidzein and genistein content between the diets. Serum isoflavone concentrations in all individuals and groups increased rapidly after the ingestion of each soy food; as expected, genistein concentrations exceeded daidzein concentrations in serum. In this small study, gender differences in peak concentrations of daidzein were observed, with higher levels attained in women. Consumption of tempeh (mainly isoflavone aglycon) resulted in higher serum peak levels of both daidzein (P < 0.001) and genistein (P < 0.01) and the associated area under the curve (P < 0.001 and P < 0.03, respectively) compared with textured vegetable protein (predominantly isoflavone glucosides). However, soy milk was absorbed faster and peak levels of isoflavones were attained earlier than with the other soy foods. Only 30% of the subjects were equol producers and no differences in equol production with age or gender were observed.     

Effects of soy intake on sex hormone metabolism in premenopausal women

Studies suggest that phytoestrogens in soy products may impart hormonal effects that protect women against breast cancer. Limited research suggests that intake of soy products high in isoflavonoid phytoestrogens affects sex hormone metabolism, but it is unknown whether phytoestrogens in soy have any effect on menstrual function or serum sex hormones in women on common hormone therapies, such as oral contraceptives (OC). We studied the effects of soy in 36 premenopausal women, 20 of whom used OC. Subjects consumed their normal diet for two menstrual cycles and added a soy beverage containing 20 g of protein and 38 mg of total isoflavones to their usual diet for another two menstrual cycles. No significant differences were observed in serum estrone, estradiol, sex hormone-binding globulin, dehydroepiandrosterone sulfate, prolactin, or progesterone concentrations with soy feeding in the non-OC or the OC group. No changes in menstrual cycle length or the urinary estrogen metabolite ratio of 2-hydroxyestrone to 16 alpha-hydroxyestrone were seen with soy feeding in the non-OC or the OC group. Levels of urinary estrogen metabolites were significantly different between the non-OC and the OC group. Thus soy consumption had no significant effect on the menstrual cycle, serum sex hormones, or urinary estrogen metabolite ratio in premenopausal OC or non-OC users.     

大豆异黄酮的测定方法研究

目的:检测大豆及其制品中黄豆甙、大黄豆甙、染料木甙、黄豆甙元、大黄豆素和金雀异黄素,建立大豆及其制品中6种大豆异黄酮的高效液相色谱-二极管阵列检测器(HPLC-PDA)检测方法。方法:保健食品、豆腐等样品中的大豆异黄酮直接用甲醇水(80+20,v/v)超声提取30 m in,定容过0.45μm滤膜后测定;豆粉和豆奶粉等样品中的大豆异黄酮及其酯类用甲醇水(80+20,v/v)超声提取,提取液经碱性皂化,将某些酯类转化成对应的大豆异黄酮,经盐酸中和,甲醇水(80+20,v/v)定容,过滤膜后测定;酱油和豆豉等样品超声提取30 m in,提取液经OASIS HLB柱去杂质,过0.45μm滤膜,进行液相色谱分析。样品中的6种大豆异黄酮用甲醇和醋酸铵(0.025 mol/L,pH 4.1)作流动相,流速2.0 m l/m in进行梯度洗脱,经250×4.6 mm粒径10μm C18柱分离,二极管阵列检测器(210~400 nm)测定。30 m in内6种大豆异黄酮可得到良好分离。结果:测定6种大豆异黄酮的平均加标回收率在86.7%~116%,加标回收相对标准偏差均小于8%,最底检出限量小于0.04μg。结论:本方法适用于大豆及其制品中大豆异黄酮的测定。     

Treatment with soy isoflavones during early adulthood improves metabolism in early postnatally overfed rats

Purpose: The incidences of obesity and related diseases have reached epidemic proportions, and new therapeutic approaches are needed. Soy isoflavones have been identified as an important dietary factor for preventing and treating metabolic dysfunction. This study examined the effects of high doses of isoflavone on glucose and fat metabolism in a model of programmed obesity and evaluated its effects on the autonomic nervous system.

Methods: Litters of Wistar rats were standardized at nine pups per dam in normal litters (NL) or reduced to three pups per dam at the third day of life (P3) in small litters (SL) to induce postnatal overfeeding. Gavage with a soy bean isoflavone mixture (1?g/day) diluted in water was started at P60 and continued for 30 days. The control animals received vehicle gavage. At P90, biometric and metabolic parameters as well as direct autonomic nerve activity were measured.

Results: Increases in glycaemia and insulinaemia observed in SL rats were reduced by isoflavone treatment, which also caused lower glucose-induced insulin secretion by pancreatic islets. Sympathetic activity in the major splanchnic nerve was increased, while vagus nerve activity was reduced by isoflavone treatment. The dyslipidaemia induced by overfeeding in SL rats was restored by isoflavone treatment.

Conclusion: The present study shows that treatment with isoflavone reduces adiposity and improves glucose and lipid metabolism. Collectively, these effects may depend on autonomic changes.     

Goitrogenic and estrogenic activity of soy isoflavones

Soy is known to produce estrogenic isoflavones. Here, we briefly review the evidence for binding of isoflavones to the estrogen receptor, in vivo estrogenicity and developmental toxicity, and estrogen developmental carcinogenesis in rats. Genistein, the major soy isoflavone, also has a frank estrogenic effect in women. We then focus on evidence from animal and human studies suggesting a link between soy consumption and goiter, an activity independent of estrogenicity. Iodine deficiency greatly increases soy antithyroid effects, whereas iodine supplementation is protective. Thus, soy effects on the thyroid involve the critical relationship between iodine status and thyroid function. In rats consuming genistein-fortified diets, genistein was measured in the thyroid at levels that produced dose-dependent and significant inactivation of rat and human thyroid peroxidase (TPO) in vitro. Furthermore, rat TPO activity was dose-dependently reduced by up to 80%. Although these effects are clear and reproducible, other measures of thyroid function in vivo (serum levels of triiodothyronine, thyroxine, and thyroid-stimulating hormone; thyroid weight; and thyroid histopathology) were all normal. Additional factors appear necessary for soy to cause overt thyroid toxicity. These clearly include iodine deficiency but may also include additional soy components, other defects of hormone synthesis, or additional goitrogenic dietary factors. Although safety testing of natural products, including soy products, is not required, the possibility that widely consumed soy products may cause harm in the human population via either or both estrogenic and goitrogenic activities is of concern. Rigorous, high-quality experimental and human research into soy toxicity is the best way to address these concerns. Similar studies in wildlife populations are also appropriate.     

Antioxidant action of soy isoflavones on oxidative stress and antioxidant enzyme activities in exercised rats

BACKGROUND/OBJECTIVES

Isoflavones are widely believed to be beneficial to human health, in relation to their antioxidant potentials. Exercise can cause an imbalance between reactive oxygen species (ROS) and antioxidants. This study was conducted in order to investigate the ability of isoflavones in amelioration of oxidative stress induced by exercise.

MATERIALS/METHODS

Male Sprague-Dawley rats were assigned to one of four groups: isoflavone-free with no exercise (CON-sd), isoflavone-free with exercise (CON-ex), isoflavone-supplemented with no exercise (ISF-sd), and isoflavone-supplemented with exercise (ISF-ex). Animals exercised on the treadmill for 30 minutes per day, five days per week. TBARS as a marker of oxidative stress and antioxidant enzyme activity, including SOD, GSH-px, and catalase were determined in liver tissue. Serum lipid profile was also examined.

RESULTS

A significant effect of isoflavone alone was observed on abdominal fat pad mass. ISF-ex had significantly less abdominal fat pad than CON-ex. Both exercise and isoflavone treatment had significant effects on lowering plasma triglyceride (TG), thus, the ISF-ex group had a significantly lower TG level than the CON-sd group, by 30.9%. However, no differences were observed in plasma cholesterol, HDL-C, and cholesterol/HDL-C ratio. Exercise, isoflavone, and exercise-isoflavone interaction effects were significant on thiobarbituric acid reactive substances (TBARS) (P = 0.001, 0.002, and 0.005, respectively). The CON-ex group showed a higher TBARS level than the other three groups. By contrast, in the ISF-ex group, TBARS was restored to the level of the ISF-sd or CON-sd group. Isoflavone had a significant effect on superoxide dismutase (SOD) (P = 0.022) and catalase activities (P = 0.049). Significantly higher SOD and catalase activities were observed in ISF-ex than CON-ex. SOD and catalase activities showed an inverse pattern of TBARS. Taken together, isoflavones increased the activities of SOD and catalase with concomitant decreases in TBARS, indicative of decreased oxidative stress.

CONCLUSIONS

Isoflavone supplementation enhances antioxidant action with attenuation of exercise-induced oxidative stress, as measured by decreases in TBARS, and inhibits body fat accumulation and plasma TG increase. Antioxidative effects ascribed to isoflavones may be partially exerted via enhancement of antioxidant enzyme activities.     

Chemoprevention of rat prostate carcinogenesis by soy isoflavones and by Bowman-Birk inhibitor

Epidemiology studies suggest that soy consumption confers protection against human prostate cancer. To identify the soy component(s) that may be responsible for this chemopreventive activity, studies were conducted to determine the influence of a soy isoflavone mixture (PTI G-2535; 45% genistein, 22% daidzein, 2% glycitein) and a soy-derived protease inhibitor (Bowman-Birk Inhibitor Concentrate; BBIC) on prostate carcinogenesis in rats. Prostate cancers were induced in male Wistar-Unilever rats by a sequential regimen of cyproterone acetate and testosterone propionate, followed by a single intravenous injection of N-methyl-N-nitrosourea (MNU) and chronic androgen stimulation. In separate studies, PTI G-2535 and BBIC were administered continuously at 0 (control), 200, or 2000 mg/kg diet, beginning 1 wk post-MNU. PTI G-2535 and BBIC both conferred modest, but statistically significant and dose-related protection against carcinogenesis in the dorsolateral+anterior prostate. These data demonstrate that both the isoflavone and protein (protease inhibitor) components of soy can inhibit prostate carcinogenesis in the rat. However, the modest individual activities of soy isoflavones and BBIC suggest that while both components may contribute to the chemopreventive activity of soy, combination administration (or exposure to whole soy) may be more effective in prostate cancer prevention than is administration of either component alone.