Dietary soy isoflavone-aglycone lowers food intake in female rats with and without ovariectomy

Traditional uses, botany, phytochemistry, pharmacology and applications of Labisia pumila: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Labisia pumila (Blume) Fern.-Vill, also known as Kacip Fatimah, is a traditional medicinal herb common throughout Southeast Asia. It is primarily used to facilitate childbirth and postpartum recovery in women. Additionally, it can also be used to treat dysentery, rheumatism, gonorrhea, and as an anti-flatulent.

AIM OF THIS REVIEW

This article aims to provide a comprehensive review of the traditional uses, botany, cultivation, phytochemistry, pharmacological effects, practical applications, and potential uses of L. pumila (LP). Furthermore, we also explore the safety of this plant and its potential prospects for application.

MATERIALS AND METHODS

The keywords "Labisia pumila," "Kacip Fatimah," and "Marantodes pumilum" were used to collect relevant information through electronic searches (including Elsevier, PubMed, Google Scholar, Baidu Scholar, CNKI, ScienceDirect, and Web of Science).

RESULTS

This review summarizes 102 chemical components from different parts of the plant, including flavonoids, phenolic acids, saponins, and other chemical components. In addition, we also address the associated cultivation conditions, traditional uses, pharmacological effects and toxicity. A large number of reports indicate that LP has various pharmacological effects such as antioxidant, phytoestrogenic, anti-inflammtory, antimicrobial, anti-osteoporosis and anti-obesity properties. These results provide valuable references for future research on LP. In addition, LP is also a potential medicinal and edible plant, and is currently sold on the market as a dietary supplement.

CONCLUSIONS

LP is a renowned traditional ethnic medicine with numerous pharmacological activities attributed to its bioactive components. Therefore, isolation and identification of the chemical components in LP can be a focus of our future research. Current studies have focused only on the effects of LP on estrogen deficiency-related diseases in women and bone diseases. There is no scientific evidence for other traditional uses. Therefore, it is important to further explore its pharmacological activities and fill the research gaps related to other traditional uses. Furthermore, research on its safety should be expanded to prepare clinical applications.

Daidzein, but not genistein, has anxiolytic-liked effect on intact male Wistar rats

The phytoestrogens daidzein and genistein are ubiquitous in human food. This study aimed to elucidate their anxiety-liked effects, their effects on the reproductive organs, and the molecular mechanism behind any anxiety-liked effects in intact adult male Wistar rats. These phytoestrogens are of interest due to their posited health benefits, particularly for female, but with some effect on males as well. This study comprised two experiments: (1) Male Wistar rats received either a vehicle, daidzein, or genistein (0.25, 0.50, or 1.00 mg/kg) by subcutaneously injection for four weeks. They were then tested for anxiety-liked behaviors. Then, the brain monoamines in anxiolytic rats were determined; (2) The modulation of gamma aminobutyric acid receptors by phytoestrogens was further analyzed by administration of diazepam to phytoestrogen-treated rats before behavioral tests. In the first experiment, the biological parameters measured, including body weight, daily food intake and reproductive organ weights were unaffected by either genistein or daidzein. However, anxiolytic-like effect was observed in the low-dose daidzein (0.25 mg/kg) group. Higher doses of daidzein or genistein of all doses had no effect. Further, the low-dose daidzein did not alter brain monoamine levels. In the second experiment, the anxiolytic-like behavior of daidzein-treated rats receiving diazepam did not differ from that of the rats treated with just diazepam or just daidzein. In conclusion, 4-week exposure to daidzein or genistein had no negative effects on the reproductive organs, body weight, food intake, anxiogenic-like behavior, or monoaminergic and diazepam-modulated GABAergic neurotransmissions of intact male rats. However, beneficial anxiolytic-like effects were apparent after low-dose treatment with daidzein.

Mechanism of Soy Isoflavone Daidzein-Induced Female-Specific Anorectic Effect

Epidemiological studies suggest that regular intake of soy isoflavone exerts a preventive effect on postmenopausal obesity and other forms of dysmetabolism. Estrogens inhibit eating behavior. Soy isoflavones may act as estrogen agonist in estrogen-depleted conditions, whereas they may either act as an estrogen antagonist or be ineffective in estrogen-repleted conditions. We investigated the effects of dietary soy isoflavone on food intake under various estrogen conditions using male, ovariectomized (OVX), and non-OVX female rats, and compared the effects with those of estradiol. We found that soy isoflavones reduced food intake in females specifically, regardless of whether ovariectomy had been performed, whereas subcutaneous implantation of estradiol pellet did not reduce food intake in intact female rats, but did so in OVX female and male rats. Contrary to this hypothesis, the reduction in food intake may not be caused by the estrogenic properties of soy isoflavones. It is of great interest to understand the mechanisms underlying the anorectic effects of soy isoflavones. In this non-systematic review, we summarize our recent studies that have investigated the bioactive substances of anorectic action, pharmacokinetic properties of soy isoflavones, and the modification of central and peripheral signals regulating appetite by soy isoflavones, and selected studies that were identified via database mining.

Long-term oral administration of a novel estrogen receptor beta agonist enhances memory and alleviates drug-induced vasodilation in young ovariectomized mice

Development of estrogen therapies targeting the β (ERβ) but not α (ERα) estrogen receptor is critically needed for the treatment of negative menopausal symptoms, as ERα activation increases health risks like cancer. Here, we determined the effects of long-term oral treatment with EGX358, a novel highly selective ERβ agonist, on memory, vasodilation, and affect in young ovariectomized mice. Mice were orally gavaged daily for 9 weeks with vehicle, 17β-estradiol (E₂), the ERβ agonist diarylpropionitrile (DPN), or EGX358 at doses that enhance memory when delivered acutely. Tail skin temperature was recorded as a proxy for vasodilation following injection of vehicle or senktide, a tachykinin receptor 3 agonist used to model hot flashes. Anxiety-like behavior was assessed in the open field (OF) and elevated plus maze (EPM), and depression-like behavior was measured in the tail suspension (TST) and forced swim tests (FST). Finally, memory was assessed in object recognition (OR) and object placement (OP) tasks. E₂, DPN, and EGX358 reduced senktide-mediated increases in tail skin temperature compared to vehicle. All three treatments also enhanced memory in the OR and OP tasks, whereas vehicle did not. Although E₂ increased time spent in the center of the OF, no other treatment effects were observed in the OF, EPM, TST, or FST. These data suggest that long-term ERβ activation can reduce hot flash-like symptoms and enhance spatial and object recognition memories in ovariectomized mice. Thus, the highly selective ERβ agonist EGX358 may be a promising avenue for reducing menopause-related hot flashes and memory dysfunction.

Dietary daidzein decreases food intake accompanied with delayed gastric emptying in ovariectomized rats

We previously found that equol, a metabolite of intestinal bacterial conversion from soy isoflavone daidzein, has female-specific anorectic effects. In the present study, we used seven-week-old female ovariectomized (OVX) Sprague Dawley rats to test the hypothesis that the anorectic effect of dietary daidzein may be attributed to delayed gastric emptying. Results suggest that dietary daidzein delays gastric emptying and that it has an anorectic effect with residual gastric contents, but not without gastric contents. Dietary equol significantly decreased daily food intake in the OVX rats without sleeve gastrectomy, but not in those with sleeve gastrectomy, suggesting that the accumulation of food in the stomach is required for the anorectic effect of equol to occur. These results support the hypothesis that the anorectic effect of dietary daidzein is attributed to delayed gastric emptying.

Targeting obesity with plant-derived pancreatic lipase inhibitors: A comprehensive review

The prevalence of obesity is alarmingly increasing in the last few decades and leading to many serious public health concerns worldwide. The dysregulated lipid homeostasis due to various genetic, environmental and lifestyle factors is considered one of the critical putative pathways mediating obesity. Nonetheless, the scientific advancements unleashing the molecular dynamics of lipid metabolism have provided deeper insights on the emerging roles of lipid hydrolysing enzymes, including pancreatic lipase. It is hypothesized that inhibiting pancreatic lipase would prevent the breakdown of triglyceride and delays the absorption of fatty acids into the systemic circulation and adipocytes. Whilst, orlistat is the only conventional pancreatic lipase enzyme inhibitor available in clinics, identifying the safe clinical alternatives from plants to inhibit pancreatic lipase has been considered a significant advancement. Consequently, plants which have shown significant potential to combat obesity are now revisited for its abilities to inhibit pancreatic lipase. In this regard, our review surveyed the potential of medicinal plants and its phytoconstituents to inhibit pancreatic lipase and to elicit anti-obesity effects. Thus, the review collate and critically appraise the potential of medicinal plants and phyto-molecules inhibiting pancreatic lipase enzyme and consequently modulating triglyceride absorption in gut, and discuss its implications in the development of novel therapeutic strategies to combat obesity.

Dietary daidzein induces accumulation of S-equol in enterohepatic circulation to far higher levels than that of daidzein in female rats with and without ovariectomy

We previously found that daidzein decreased food intake in female rats. To understand the mechanism of anorectic action of dietary daidzein, it is necessary to determine distributions of daidzein and S-equol, a metabolite of intestinal bacterial conversion from daidzein, in the body. In the present study, we measured the concentrations of daidzein and S-equol in serum and bile in sham-operated and ovariectomized female rats fed a diet containing 150 mg/kg daidzein for 7 days. Dietary daidzein increased serum and bile concentrations of S-equol to far higher levels than those of daidzein. S-equol concentration was more than several hundred fold-higher in bile than in serum, regardless of ovariectomy. Moreover, to investigate whether accumulation of S-equol is facilitated by efficient enterohepatic circulation during continuous intake of daidzein and S-equol, female rats were fed diet containing daidzein or S-equol (both 150 mg/kg), or control diet for 1, 2, 3, or 5 days. Dietary daidzein significantly increased serum and bile concentrations of S-equol in a time-dependent manner, but not those of daidzein. These results indicated that substantial proportion of dietary daidzein was converted to S-equol, which underwent efficient enterohepatic circulation and predominantly accumulated there.

Dietary daidzein, but not genistein, has a hypocholesterolemic effect in non-ovariectomized and ovariectomized female Sprague-Dawley rats on a cholesterol-free diet

We compared the effects of two major isoflavones, daidzein and genistein, on lipid metabolism in rats. Daidzein (150 mg/kg diet), genistein (150 mg/kg diet), daidzein and genistein (1:1, 300 mg/kg diet), or control diets were fed to 4 groups of 6-week-old ovariectomized (Ovx) and non-Ovx Sprague Dawley rats for 4 weeks. Dietary daidzein, but not genistein, reduced serum and hepatic total cholesterol levels significantly relative to that by the control group, regardless of whether the rats had undergone ovariectomy. Genistein did not exhibit any physiological effects on lipid levels, but did affect genes involved in cholesterol metabolism. These results indicate that daidzein and genistein may influence lipid regulation via differing modes of action.

Difructose anhydride III decreases body fat as a low-energy substitute or by decreasing energy intake in non-ovariectomized and ovariectomized female rats

We evaluated the effects of difructose anhydride III (DFAIII) on body weights of ovariectomized rats, which are a good model for obesity by estrogen deficiency-induced overeating. Female rats (10 weeks old) were subjected to ovariectomy or sham operation and then fed with or without a diet containing 3% or 6% DFAIII for 33 days or pair-fed control diet during the same period. Rats fed DFAIII showed significantly decreased food intake, energy intake, body weight gain, body energy accumulation, and fat tissue weight than control group, regardless of ovariectomy. DFAIII may decrease body fat dependent of reduced food/energy intake. Compared with the respective pair feeding groups, rats fed DFAIII showed significantly decreased body energy and fat tissue weight, regardless of ovariectomy, suggesting its potential as a low-energy substitute for high-energy sweeteners. The low energy of DFAIII may contribute to decreased body fat, which may not be dependent on obesity.

Dietary supplementation with a high dose of daidzein enhances the antioxidant capacity in swine muscle but experts pro-oxidant function in liver and fat tissues

Background

Although isoflavones are natural dietary antioxidants, they may have toxicological effects. This study aimed to evaluate the redox system in tissues of finishing pigs by supplementation with high dose of daidzein (640 mg/kg).

Results

The supplementation of high dose of daidzein for 64 d increased the activity of superoxide dismutase and total antioxidant capacity in longissimus muscle but down-regulated the expression of reactive oxygen species (ROS)-producing enzyme NADPH oxidase-2 and cyclooxygenase-2. In contrast, high-level supplementation with daidzein exerted pro-oxidant changes in back fat, abdominal fat, liver, and plasma, as reflected by increased contents of malondialdehyde, a lipid peroxidation product, in these tissues. Furthermore, daidzein supplementation resulted in higher expression of ROS-producing enzymes, including NADPH oxidase-1 and cyclooxygenase-1 in liver, 5-lipoxygenase (5-LOX) in backfat and NADPH oxidase-2 both in abdominal fat and backfat. The supplementation of daidzein did not affect meat quality parameters in longissimus muscle, including marbling score, eye muscle areas, intramuscular fat, shear force, drip loss, pH and meat color.

Conclusions

This experiment suggests that dietary supplementation of finishing pigs with daidzein at a high dose level improves redox status in muscle but exerts pro-oxidant effect in liver and fat tissues.

The daidzein- and estradiol- induced anorectic action in CCK or leptin receptor deficiency rats

We investigated the effect of daidzein feeding and estradiol treatment on food intake in cholecystokinin-1 receptor (CCK1R) deficiency, leptin receptor (ObRb) deficiency rats and their wild-type rats. These rats underwent an ovariectomy or a sham operation. For the 5 week experiment, each rat was divided in three groups: control, daidzein (150 mg/kg diet), and estradiol (4.2 μg/rat/day) groups. In both CCK1R+ and CCK1R− rats, daidzein feeding and estradiol treatment significantly decreased food intake. Daidzein feeding significantly reduced food intake in ovariectomized ObRb− rats, although not in ObRb+ rats. Estradiol treatment significantly lowered food intake in ovariectomized ObRb+ and ObRb− rats. In the ovariectomized rats, estradiol treatment significantly increases uterine weight, while daidzein feeding did not change it, suggesting that daidzein might have no or weak estrogenic effect in our experiment. These results suggest that CCK1R and ObRb signalings were not essential for the daidzein- and estradiol-induced anorectic action.

Dynamics of appetite-mediated gene expression in daidzein-fed female rats in the meal-feeding method

We previously found that daidzein decreased food intake in female rats. The present study aimed to elucidate the relationship between dynamics of appetite-mediated neuropeptides and the anorectic effect of daidzein. We examined appetite-mediated gene expression in the hypothalamus and small intestine during the 3 meals per day feeding method. Daidzein had an anorectic effect specifically at the second feeding. Neuropeptide-Y (NPY) and galanin mRNA levels in the hypothalamus were significantly higher after feeding in the control but not in the daidzein group, suggesting that daidzein attenuated the postprandial increase in NPY and galanin expression. The daidzein group had higher corticotrophin-releasing hormone (CRH) mRNA levels in the hypothalamus after feeding, and increased cholelcystokinin (CCK) mRNA levels in the small intestine, suggesting that CCK is involved in the hypothalamic regulation of this　anorectic effect. Therefore, daidzein may induce anorexia by suppressing expression of NPY and galanin and increasing expression of CRH in the hypothalamus.

Equol producers can have low leptin levels among prediabetic and diabetic females

OBJECTIVES

Soy isoflavones have received great attention for their beneficial effects on health and disease, i.e., in patients with diabetes. Equol is a biologically active isoflavone-related metabolite with interindividual differences in its production. The current study investigated the relationship between an equol-producing state and the levels of adipocytokine markers in a prediabetic and diabetic population.

SUBJECTS AND METHODS

A total of 79 subjects (34 males/45 females) in a prediabetic or diabetic state recruited from the general population were examined regarding their ability to produce equol using urine samples. Clinical data, such as age, smoking as well as anthropometric and biochemical variables, including body mass index (BMI), lipids, insulin, glucose, hemoglobin A1c, leptin and adiponectin, were recorded.

RESULTS

Equol producers exhibited lower leptin and leptin/BMI than non-producers among females. Simple correlation tests and stepwise multiple regression analyses revealed a significant inverse correlation between the leptin/BMI and equol-production. This relationship was not found in males.

CONCLUSIONS

Female equol producers can have favorable metabolic traits in relation to leptin metabolism in this population. Further studies are needed to confirm these results.

Effects of daidzein and kiwifruit on bone mineral density and equol production in ovariectomised rats

In this study, we investigated the synergistic effects of daidzein (Dz) and kiwifruit on bone and equol production in ovariectomised (OVX) rats. Female Sprague-Dawley rats were randomly assigned to one of five groups: sham operated, OVX control, OVX fed 0.1% Dz-supplemented diet (OVX + Dz), OVX fed 0.1% Dz and green kiwifruit (GRK)-supplemented diet (OVX + Dz + GRK) and OVX fed 0.1% Dz and gold kiwifruit (GOK)-supplemented diet (OVX + Dz + GOK). There were no significant differences in whole body and femur bone mineral density (BMD) among groups at week 8. BMD in the OVX group significantly decreased at week 8; however, BMD in the OVX + Dz + GRK was not significantly different from baseline in the end of the study. However, supplementation with kiwifruit did not affect urinary equol concentrations, urinary ratios of equol to Dz and the composition of caecal microbiota. These results suggest that the combination of Dz and GRK may slightly reduce bone loss caused by oestrogen deficiency but does not affect equol production.

Isoflavone intake inhibits the development of 7,12-dimethylbenz(a)anthracene(DMBA)-induced mammary tumors in normal and ovariectomized rats

To determine the associations between isoflavone (49.72% genistin, 5.32% daidzin, 34.54% glycitin) and breast cancer risk, 150 rats were given 5 mg 7,12-dimethylbenz(a)anthracene and half of them were ovariectomized. Then normal rats and ovariectomized rats were divided into 5 groups: control group, isoflavone high (HI), middle (MI), or low (LI) dose group consuming 100, 500, or 1000 mg isoflavones/kg diet, estrogen group (2.5 mg stilboestrol/kg diet). After 24 weeks, tumor incidences were 73% in control group, 7% in HI, 7% in MI, 27% in LI, and 80% in estrogen group for normal rats; 60% in control group, 13% in HI, 7% in MI, 13% in LI, and 73% in estrogen group for ovariectomized rats. Isoflavone treatment decreased tumor incidence and mean tumor number per rat and increased mean latent period compared with those in control group and estrogen group group significantly (p<0.05). The mRNA and protein expression of estrogen receptor β were significantly higher in isoflavone treatment groups than those in control group group. Moreover, isoflavone treatment significantly decreased 8-hydroxydeoxyguanosine content and increased superoxide dismutase level in normal rats and decreased malondialdehyde concentrations in ovariectomized rats compared with control group. In conclusions, isoflavone intake significantly inhibited the development of premenopausal and postmenopausal mammary tumors.

Estrogen-dependent effect of soy extract on pentylenetetrazole-induced seizures in rats

OBJECTIVE

To study the different effects of soy extract on pentylenetetrazole (PTZ)-induced seizures in the presence and absence of ovarian hormones in rats, and the gender-dependent differences in the effects of phytoestrogens on behavior.

METHODS

Male and female Wistar rats were randomly divided into nine groups with eight in each, namely, male-saline (M-saline), male-low-dose soy (M-LDS), male-high-dose soy (M-HDS), sham-saline (Sh-saline), sham-low-dose soy (Sh-LDS), sham-high-dose soy (Sh-HDS), ovariectomized-saline (OVX-saline), ovariectomized-low-dose soy (OVX-LDS) and ovariectomized-high-dose soy (OVX-HDS). The rats of groups 7 to 9 were ovariectomized under ketamine anesthesia. The rats of groups 2, 5 and 8 were treated by 20 mg/kg of soy extract while the animals of groups 3, 6 and 9 received 60 mg/kg of soy extract for two weeks. In groups 1, 4 and 7, saline was injected instead of soy extract. The animals were then injected by a single dose of PTZ (90 mg/kg body weight, intraperitoneally) and placed in a plexiglas cage and the latency to minimal clonic seizure (MCS) and generalized tonic-clonic seizure (GTCS) was recorded.

RESULTS

Both MCS and GTCS latency in M-LDS and M-HDS groups was significantly lower than that in M-saline group (P<0.05 or P<0.01). Treatment for female sham rats by soy extract did not affect MCS and GTCS latency. The animals of OVX-LDS and OVX-HDS groups had lower MCS and GTCS latency in comparison with OVX-saline group (P<0.05 or P<0.01).

CONCLUSION

It is concluded that the phytoestrogens of soy affect seizure severity induced by PTZ, but their effects are different in the presence or absence of ovarian hormones. However, further studies are necessary to be done.

Dietary saturated fat intake is negatively associated with weight maintenance among the PREMIER participants

Research finding on the composition of macronutrient intakes on body weight has not been consistent. Furthermore, little research has examined the impact of subcomponents of macronutrients such as saturated fat or plant protein on body weight. The purpose of this report was to examine the impact of saturated fat, animal and plant protein, and other macronutrient intakes at the end of an intensive intervention on subsequent follow-up body weight. This is a secondary, observational data analysis using data from PREMIER, an 18-month randomized clinical trial that enrolled a total of 810 participants. Participants completed group and individual sessions designed to help them improve blood pressure (BP) control by making lifestyle changes. Dietary intakes were assessed by two 24-h diet recalls at baseline, 6, and 18 months. Body weight and physical fitness were monitored regularly. Regression models were used to examine the impact of animal or plant protein and other macronutrient intakes on subsequent body weight. After controlling for potential confounders, none of the calorie-contributing nutrient intakes at baseline was associated with subsequent weight at 6 or 18 months. However, a greater intake of saturated fat at 6 months was associated with higher weight at 18 months (P = 0.002). A greater intake of plant protein at 6 month was marginally associated with lower absolute weight at 18 month (P = 0.069). We conclude that macronutrient intakes before the intervention were not associated with subsequent body weight at 6 or 18 months. However, a lower saturated fat intake achieved after 6-month intervention predicts a lower body weight at 18 months and thus greater weight-loss maintenance.

Impact of perinatal exposure to equol enantiomers on reproductive development in rodents

There is now considerable interest in the intestinally derived soy isoflavone metabolite, equol, which occurs in the enantiomeric forms, S-(-)equol and R-(+)equol, both differing in biological actions. Little is known about effects of either enantiomer on reproductive development, yet such knowledge is fundamental because of the recent commercialization of S-(-)equol as a dietary supplement. S-(-)equol and R-(+)equol were therefore investigated to determine their effects on reproductive development and fertility in the Sprague-Dawley rat. Neither enantiomer affected fertility, number of litters produced, number of pups per litter, number of male and female pups born, birth weight, anogenital distance, testicular descent or vaginal opening. Histological analysis showed no major abnormalities in ovary, testis, prostate or seminal vesicle tissue with dietary exposure to S-(-)equol or R-(+)equol, but both enantiomers triggered hyperplasia of uterine tissue. With R-(+)equol this stimulatory effect subsided after exposure was discontinued, but the effect of S-(-)equol was prolonged.

Mammary gland differentiation by early life exposure to enantiomers of the soy isoflavone metabolite equol

The role of soy in reducing breast cancer risk has been suggested to be associated with early exposure to isoflavones, which alter mammary gland morphology. The objective of the study was to determine the effect of dietary exposure to the enantiomers of a key soy isoflavone metabolite, equol, on mammary gland development and later chemoprotection using the DMBA-induced animal model of breast cancer. Animals were exposed to S-(-)equol or R-(+)equol (250 mg/kg diet) during the neonatal (0-21 days) or prepubertal (21-35 days) periods only. Histological evaluation of the mammary glands showed that both enantiomers fed neonatally via the dam led to significant precocial mammary gland differentiation. By day 50, early S-(-)equol or R-(+)equol exposure resulted in a decrease in immature terminal end structures and an increase in mature lobules, suggesting an early 'imprinting' effect. Despite these morphological changes to the mammary gland, neonatal and prepubertal exposure to equol had no long-term chemoprevention against mammary tumors induced by DMBA, although for R-(+)equol there was a trend to delaying tumor formation. In summary, early exposure to equol was not chemopreventive, but neither did it increase tumor formation in response to DMBA, suggesting exposure in early life does not influence breast cancer risk.

The chemopreventive action of equol enantiomers in a chemically induced animal model of breast cancer

We describe for the first time the chemopreventive effects of S-(-)equol and R-(+)equol, diastereoisomers with contrasting affinities for estrogen receptors (ERs). S-(-)equol, a ligand for ERbeta, is an intestinally derived metabolite formed by many humans and by rodents consuming diets containing soy isoflavones. Whether the well-documented chemopreventive effect of a soy diet could be explained by equol's action was unclear because neither diastereoisomers had been tested in animal models of chemoprevention. Sprague-Dawley rats (n = 40-41 per group) were fed a soy-free AIN-93G diet or an AIN-93G diet supplemented with 250 mg/kg of S-(-)equol or R-(+)equol beginning day 35. On day 50, mammary tumors were induced by dimethylbenz[a]anthracene and thereafter, animals were palpated for number and location of tumors. On day 190, animals were killed and mammary tumors were removed and verified by histology, and the degree of invasiveness and differentiation was determined. S-(-)equol and R-(+)equol plasma concentrations measured on days 35, 100 and 190 by tandem mass spectrometry confirmed diet compliance and no biotransformation of either diastereoisomer. In this model, S-(-)equol had no chemopreventive action, nor was it stimulatory. In contrast, R-(+)equol compared with Controls reduced palpable tumors (P = 0.002), resulted in 43% fewer tumors (P = 0.004), increased tumor latency (88.5 versus 66 days, P = 0.003), and tumors were less invasive but showed no difference in pattern grade or mitosis. Both enantiomers had no effect on absolute uterine weight but caused a significant reduction in body weight gain. In conclusion, the novel finding that the unnatural enantiomer, R-(+)equol, was potently chemopreventive warrants investigation of its potential for breast cancer prevention and treatment.

Soy isoflavone and its effect to regulate hypothalamus and peripheral orexigenic gene expression in ovariectomized rats fed on a high-fat diet

OBJECTIVE

To explore the effect of soy isoflavone on obesity in the light of hypothalamus and peripheral orexigenic gene regulation.

METHODS

Fifty-four female rats were randomly assigned to 6 groups: one sham-operated group (SHAM), one ovariectomized (OVX) control group, three OVX groups fed with 400 ppm (L-SI), 1200 ppm (M-SI) and 3600 ppm (H-SI) isoflavone respectively, and one OVX group receiving 0.45 ppm diethylstilbestrol (EC). All rats were allowed to take high-fat diet for 4 weeks. Some neuropeptides were measured by RT-PCR. These neuropeptides included NPY, pro-opiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART), orexin, melanin-concentrating hormone (MCH), melanin-concentrating hormone precursor (P-MCH), ghrelin, and leptin.

RESULTS

Compared with the OVX control group, the body weight and food intake in the H-SI group were reduced significantly and there was a significant dose-dependent manner in the 3 isoflavone groups. The results of RT-PCR showed that the NPY level in the 3 isoflavone groups was significantly increased and the POMC/CART gene expression decreased significantly in rats' hypothalamus compared with that in the OVX control group. However, the expression of orexin, MCH and P-MCH had no change. The peripheral grelin mRNA expression was higher in the 3 isoflavone groups, while leptin gene expression in the fat was not consistent.

CONCLUSIONS

This research showed that isoflavone could prevent obesity induced by high-fat diet and ovariectomy through regulating hypothalamus and peripheral orexigenic gene expressions associated with food intake.

Overlapping but distinct effects of genistein and ethinyl estradiol (EE(2)) in female Sprague-Dawley rats in multigenerational reproductive and chronic toxicity studies

Genistein and ethinyl estradiol (EE(2)) were examined in multigenerational reproductive and chronic toxicity studies that had different treatment intervals among generations. Sprague-Dawley rats received genistein (0, 5, 100, or 500 ppm) or EE(2) (0, 2, 10, or 50 ppb) in a low phytoestrogen diet. Nonneoplastic effects in females are summarized here. Genistein at 500 ppm and EE(2) at 50 ppb produced similar effects in continuously exposed rats, including decreased body weights, accelerated vaginal opening, and altered estrous cycles in young animals. At the high dose, anogenital distance was subtly affected by both compounds, and a reduction in litter size was evident in genistein-treated animals. Genistein at 500 ppm induced an early onset of aberrant cycles relative to controls in the chronic studies. EE(2) significantly increased the incidence of uterine lesions (atypical focal hyperplasia and squamous metaplasia). These compound-specific effects appeared to be enhanced in the offspring of prior exposed generations.

Developmental and Reproductive Effects of SE5-OH: An Equol-Rich Soy-Based Ingredient

Consumption of the isoflavones daidzein, genistein, glycitein, and their structural analogues is generally considered beneficial to human health. Equol is not found in soy, but is converted from daidzein by human gut bacterial flora. Research indicates that between 30-50% of the population is capable of converting daidzein to equol; therefore, there has been recent development of a new equol-rich functional food that relies on bacterial conversion of daidzein to equol under strictly controlled conditions. Therefore, a new equol-rich soy product (SE5-OH) has been developed, based on the bacterial conversion of daidzein; and its reproductive and developmental toxicity has been evaluated in a two-generation study and a developmental toxicity study with Sprague-Dawley rats at dose levels of 200, 1000, and 2000 mg/kg/day by gavage. SE5-OH contains approximately 0.65% equol, 0.024% daidzein, 0.022% genistein, and 0.30% glycitein. From the reproductive study, the no-observed-adverse-effect-level (NOAEL) for SE5-OH determined for both male and female rats is 1000 mg/kg/day (6.5 mg equol/kg/day). In the developmental toxicity phase of the study, no effects by SE5-OH were found in the embryo-fetus at any of the doses tested. The NOAEL for developmental effects of SE5-OH is 2000 mg/kg/day (13 mg equol/kg/day).