Marked individual variation in isoflavone metabolism after a soy challenge can modulate the skeletal effect of isoflavones in premenopausal women

Thiogenistein-Antioxidant Chemistry, Antitumor Activity, and Structure Elucidation of New Oxidation Products

Isoflavonoids such as genistein (GE) are well known antioxidants. The predictive biological activity of structurally new compounds such as thiogenistein (TGE)–a new analogue of GE–becomes an interesting way to design new drug candidates with promising properties. Two oxidation strategies were used to characterize TGE oxidation products: the first in solution and the second on the 2D surface of the Au electrode as a self-assembling TGE monolayer. The structure elucidation of products generated by different oxidation strategies was performed. The electrospray ionization mass spectrometry (ESI-MS) was used for identifying the product of electrochemical and hydrogen peroxide oxidation in the solution. Fourier transform infrared spectroscopy (FT-IR) with the ATR mode was used to identify a product after hydrogen peroxide treatment of TGE on the 2D surface. The density functional theory was used to support the experimental results for the estimation of antioxidant activity of TGE as well as for the molecular modeling of oxidation products. The biological studies were performed simultaneously to assess the suitability of TGE for antioxidant and antitumor properties. It was found that TGE was characterized by a high cytotoxic activity toward human breast cancer cells. The research was also carried out on mice macrophages, disclosing that TGE neutralized the production of the LPS-induced reactive oxygen species (ROS) and exhibits ABTS (2,2′-azino-bis-3-(ethylbenzothiazoline-6-sulphonic acid) radical scavenging ability. In the presented study, we identified the main oxidation products of TGE generated under different environmental conditions. The electroactive centers of TGE were identified and its oxidation mechanisms were proposed. TGE redox properties can be related to its various pharmacological activities. Our new thiolated analogue of genistein neutralizes the LPS-induced ROS production better than GE. Additionally, TGE shows a high cytotoxic activity against human breast cancer cells. The viability of MCF-7 (estrogen-positive cells) drops two times after a 72-h incubation with 12.5 μM TGE (viability 53.86%) compared to genistein (viability 94.46%).

Combined effects of soy isoflavone and lecithin on bone loss in ovariectomized mice

BACKGROUND/OBJECTIVES

Isoflavones (ISFs) are effective in preventing bone loss, but not effective enough to prevent osteoporosis. Mixtures of soy ISF and lecithin (LCT) were prepared and characterized in an attempt to improve the bone loss.

MATERIALS/METHODS

The daidzein (DZ) and genistein (GN) solubility in soy ISF were measured using liquid chromatography-mass spectrometry. The change in the crystalline characteristics of soy ISF in LCT was evaluated using X-ray diffraction analysis. Pharmacokinetic studies were conducted to evaluate and compare ISF bioavailability. Animal studies with ovariectomized (OVX) mice were carried out to estimate the effects on bone loss. The Student's t-test was used to evaluate statistical significance.

RESULTS

The solubility of DZ and GN in LCT was 125.6 and 9.7 mg/L, respectively, which were approximately 25 and 7 times higher, respectively, than those in water. The bioavailability determined by the area under the curve of DZ for the oral administration (400 mg/kg) of soy ISF alone and the soy ISF-LCT mixture was 13.19 and 16.09 µg·h/mL, respectively. The bone mineral density of OVX mice given soy ISF-LCT mixtures at ISF doses of 60 and 100 mg/kg daily was 0.189 ± 0.020 and 0.194 ± 0.010 g/mm³, respectively, whereas that of mice given 100 mg/kg soy ISF was 0.172 ± 0.028 g/mm³. The number of osteoclasts per bone perimeter was reduced by the simultaneous administration of soy ISF and LCT.

CONCLUSIONS

The effect of preventing bone loss and osteoclast formation by ingesting soy ISF and LCT at the same time was superior to soy ISF alone as the bioavailability of ISF may have been improved by the emulsification and solvation of LCT. These results suggest the possibility of using the combination of soy ISF and LCT to prevent osteoporosis.

Effects of Dietary Phytoestrogens on Hormones throughout a Human Lifespan: A Review

Dietary phytoestrogens are bioactive compounds with estrogenic activity. With the growing popularity of plant-based diets, the intake of phytoestrogen-rich legumes (especially soy) and legume-derived foods has increased. Evidence from preclinical studies suggests these compounds may have an effect on hormones and health, although the results of human trials are unclear. The effects of dietary phytoestrogens depend on the exposure (phytoestrogen type, matrix, concentration, and bioavailability), ethnicity, hormone levels (related to age, sex, and physiological condition), and health status of the consumer. In this review, we have summarized the results of human studies on dietary phytoestrogens with the aim of assessing the possible hormone-dependent outcomes and health effects of their consumption throughout a lifespan, focusing on pregnancy, childhood, adulthood, and the premenopausal and postmenopausal stages. In pregnant women, an improvement of insulin metabolism has been reported in only one study. Sex hormone alterations have been found in the late stages of childhood, and goitrogenic effects in children with hypothyroidism. In premenopausal and postmenopausal women, the reported impacts on hormones are inconsistent, although beneficial goitrogenic effects and improved glycemic control and cardiovascular risk markers have been described in postmenopausal individuals. In adult men, different authors report goitrogenic effects and a reduction of insulin in non-alcoholic fatty liver patients. Further carefully designed studies are warranted to better elucidate the impact of phytoestrogen consumption on the endocrine system at different life stages.

Soy Isoflavones Inhibit Endothelial Cell Dysfunction and Prevent Cardiovascular Disease

Soybeans are among the most popular foods worldwide, and intake of soy-containing foods has been associated with many health benefits in part because of it structure similar to estrogen. Epidemiologic studies have demonstrated that soy consumption improves serum profiles of hypercholesterolemic patients. Several studies have also indicated an inverse relationship between the consumption of soy isoflavones and the incidence of cardiovascular diseases (CVD). Soy is a rich dietary source of isoflavones. The main soy isoflavones are daidzein and genistein; equol, another isoflavone and a major intestinal bacterial metabolite of daidzein, is generated by enterobacterial effects. Many isoflavones have antioxidative effects and anti-inflammatory actions, as well as induce nitric oxide production to maintain a healthy endothelium and prevent endothelial cell dysfunction. These effects may limit the development of atherosclerosis and CVD and restore healthy endothelial function in altered endothelia. Although the evidence supporting the benefits of soy isoflavones in CVD prevention continues to increase, the association between soy isoflavones and disease is not fully understood. This review summarized recent progress in identifying the preventive mechanisms of action of dietary soybean isoflavones on vascular endothelial cells. Furthermore, it describes the beneficial roles that these isoflavones may have on endothelial dysfunction-related atherosclerosis.

Translating In Vitro Acrolein-Trapping Capacities of Tea Polyphenol and Soy Genistein to In Vivo Situation is Mediated by the Bioavailability and Biotransformation of Individual Polyphenols

SCOPE

Acrolein (ACR) is a highly toxic unsaturated aldehyde. Humans are both endogenously and exogenously exposed to ACR. Long-term exposure to ACR leads to various chronic diseases. Dietary polyphenols have been reported to be able to attenuate ACR-induced toxicity in vitro via formation of ACR-polyphenol conjugates. However, whether in vitro ACR-trapping abilities of polyphenols can be maintained under in vivo environments is still unknown.

METHODS AND RESULTS

Two most commonly consumed dietary polyphenols, (-)-epigallocatechin-3-gallate (EGCG) from tea and genistein from soy, are evaluated for their anti-Acrolein behaviors both in vitro and in mice. Tea EGCG exerts a much higher capacity to capture ACR than soy genistein in vitro. But translation of in vitro anti-ACR activity into in vivo is mainly mediated by bioavailability and biotransformation of individual polyphenols. It is found that 1) both absorbed EGCG and genistein can trap endogenous ACR by forming mono-ACR adducts and eventually be excreted into mouse urine; 2) both absorbed EGCG and genistein can produce active metabolites, methyl-EGCG (MeEGCG) and orobol, to scavenge endogenous ACR; 3) both MeEGCG and non-absorbed EGCG show ability to trap ACR in the gut; 4) considerable amounts of microbial metabolites of genistein display enhanced anti-ACR capacity both in the body and in the gut, compared to genistein; and 5) biotransformation of genistein is able to boost its in vivo anti-ACR capacity, compared to EGCG.

CONCLUSION

The findings demonstrate that in vivo anti-ACR ability of dietary polyphenols cannot be reflected solely based on their in vitro ability. The bioavailability and biotransformation of individual polyphenols, and especially the gut microbiome, contribute to in vivo anti-ACR ability of dietary polyphenols.

Soy isoflavones prevent bone resorption and loss, a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Osteoporosis is a common bone disease characterized by reduced bone mass resulting from continuous bone resorption.

METHODS

PubMed, Scopus, and Embase were searched to find published trials on the effect of soy isoflavones on bone mineral density (BMD) and bone turnover markers (bone-specific alkaline phosphatase, osteocalcin, osteoprotegerin, pyridinoline, deoxypyridinoline, C-telopeptide, and N-telopeptide). Random-effects inverse-variance model was used to calculate the pooled effects.

RESULTS

A total of 5313 articles were found, screened, and assessed for eligibility, and finally 52 trials were included in the meta-analysis. Consumption of soy isoflavones caused significant improvement in BMD of lumbar spine (mean difference (MD) = 0.76%; 95% CI: 0.09, 1.42%; p = 0.03), hip (MD = 0.22%; 95% CI: 0.02, 0.42%; p = 0.04), and femoral neck (MD = 2.27%; 95% CI: 1.22, 3.31%; p < 0.001). Subgroup analysis showed that in all 3 sites, the improvement was significant in normal weight subjects and interventions longer than a year, although trial location and dosage were also factors influencing isoflavones' impact on BMD. Among markers of bone turnover, osteoprotegerin (MD = 5.79; 95% CI: 3.08, 8.51 pg/ml; p < 0.001), pyridinoline (MD = -5.13; 95% CI: -7.76, -2.50 nmol/mmol; p < 0.001), and C-telopeptides (MD = -0.08; 95% CI: -0.16, -0.00 ng/ml; p = 0.04) were favorably affected by isoflavones while osteocalcin and bone alkaline phosphatase did not change. Subgroup analysis of bone markers showed that in overweight/obese individuals and dosages <90 mg/day, isoflavones are more effective.

CONCLUSIONS

Soy isoflavones prevent osteoporosis-related bone loss in any weight status or treatment duration. They increase BMD in normal weight subjects and diminish bone resorption in overweight/obese individuals. Although bone resorption may be decelerated over short-term isoflavone consumption, periods longer than a year are probably needed to affect BMD. Isoflavones also appear benefits on bone in any dose or subjects' ethnicity.

Some New Findings Regarding the Antiadhesive Activity of Cranberry Phenolic Compounds and Their Microbial-Derived Metabolites against Uropathogenic Bacteria

Findings concerning the antiadhesive activity of cranberry phenolic compounds and their microbial-derived metabolites against Gram-negative ( Escherichia coli ATCC 53503 and DSM 10791) and Gram-positive ( Enterococcus faecalis 04-1) bacteria in T24 cells are reported. A-Type procyanidins (A2 and cinnamtannin B-1) exhibited antiadhesive activity (at concentrations ≥250 μM), a feature that was not observed for B-type procyanidins (B2). The metabolites hippuric acid and α-hydroxyhippuric acid also showed effective results at concentrations ≥250 μM. With regard to conjugated metabolites, sulfation seemed to increase the antiadhesive activity of cranberry-derived metabolites as 3-(3,4-dihydroxyphenyl)propionic acid 3- O-sulfate presented active results, unlike its corresponding nonsulfated form. In contrast, methylation decreased antiadhesive activity as 3,4-dihydroxyphenylacetic acid was found to be active but not its corresponding methylated form (4-hydroxy-3-methoxyphenylacetic acid). As a whole, this work sustains the antiadhesive activity of cranberry-derived metabolites as one of the mechanisms involved in the beneficial effects of cranberries against urinary tract infections.

Trapping Methylglyoxal by Genistein and Its Metabolites in Mice

Increasing evidence supports dicarbonyl stress such as methylglyoxal (MGO) as one of the major pathogenic links between hyperglycemia and diabetic complications. In vitro studies have shown that dietary flavonoids can inhibit the formation of advanced glycation end products (AGEs) by trapping MGO. However, whether flavonoids can trap MGO in vivo and whether biotransformation limits the trapping capacity of flavonoids remain virtually unknown. In this study, we investigated whether genistein (GEN), the major soy isoflavone, could trap MGO in mice by promoting the formation of MGO adducts of GEN and its metabolites. Two different mouse studies were conducted. In the acute study, a single dose of MGO and GEN were administered to mice via oral gavage. In the chronic study, MGO was given to mice in drinking water for 1 month and then GEN was given to mice for 4 consecutive days via oral gavage. Two mono-MGO adducts of GEN and six mono-MGO adducts of GEN phase I and microbial metabolites were identified in mouse urine samples from these studies using liquid chromatography/electrospray ionization tandem mass spectrometry. The structures of these MGO adducts were confirmed by analyzing their MS(n) (n = 1-4) spectra as well as by comparing them with the tandem mass spectra of authentic standards. All of the MGO adducts presented in their phase II conjugated forms in mouse urine samples in the acute and chronic studies. To our knowledge, this is the first in vivo evidence to demonstrate the trapping efficacy of GEN in mice and to show that the metabolites of GEN remain bioactive.

Profiling of Phenolic Metabolites in Feces from Menopausal Women after Long-Term Isoflavone Supplementation

Phenolic compounds were screened by UPLC-ESI-MS/MS in the feces of 15 menopausal women before and after long-term isoflavone treatment. In total, 44 compounds were detected. Large intertreatment, interindividual, and intersample variations were observed in terms of the number of compounds and their concentration. Four compounds, the aglycones daidzein and genistein and the daidzein derivatives dihydrodaidzein and O-desmethylangolensin, were associated with isoflavone metabolism; these were identified only after the isoflavone treatment. In addition, 4-ethylcatechol, 3-hydroxyphenylacetic acid, and 3-phenylpropionic acid differed significantly in pre- and postintervention samples, whereas the concentration of 4-hydroxy-5-phenylvaleric acid showed a trend toward increasing over the treatment. The phenolic profiles of equol-producing and -non-producing groups were similar, with the exceptions of 3-hydroxyphenylacetic acid and 3-phenylpropionic acid, which showed higher concentrations in equol-non-producing women. These findings may help to trace isoflavone-derived metabolites in feces during isoflavone interventions and to design new studies to address their biological effects.

Sex, eyes, and vision: male/female distinctions in ophthalmic disorders

There is growing recognition: (1) that sex (male and female) and sex hormones (androgens and estrogens) are important for physiologic functions outside those pertaining expressly to reproduction, and (2) that both classes of sex hormones are active in both sexes, and moreover are produced locally in non-gonadal tissues throughout the body. The visual system, in addition to being of tremendous inherent importance, is unique in a very distinctive way; it possesses an organ - the eye - having a window allowing its interior to be examined with exquisite precision and control in both laboratory and clinical settings. Plus, many diseases manifest in the eye or are exclusive to the eye. This special issue of Current Eye Research contains 12 review articles, each addressing a different topical area important for Sex, Eyes, and Vision: Male/Female Distinctions in Ophthalmic Disorders. Of course, the distinctions between topical areas are blurred, and the overlap between the various lines of knowledge and investigation likewise is substantial. Eye diseases can be both neurodegenerative and involve altered blood flow, for instance. In fact, the thematic overlap is greater yet, in that the articles for this special issue address matters of interest to clinicians and scientists who may identify more with women's health or sex & gender fields than with eye & vision fields. Nevertheless, because this special issue needs a home, the following 12 topical areas each have here their own dedicated review: age-related maculopathy, central nervous system function and cognition & perception, diabetic retinopathy, dry eye, glaucoma, inherited diseases, lens and cataract, neuro-ophthalmology, ocular blood flow, ocular inflammatory disorders, optical coherence tomography, and sex/gender eye care disparities. This overview article itself raises additional points expressly concerning: (1) the estrogen therapy timing hypothesis, and (2) breast cancer treatment with aromatase inhibitors.

Profiling of microbial-derived phenolic metabolites in human feces after moderate red wine intake

A controlled and randomized trial study involving 41 healthy volunteers (33 intervention and 8 control subjects) was performed in order to establish changes in the microbial-derived phenolic metabolite profile of feces after moderate consumption of red wine (250 mL/day, 4 weeks). Out of the 35 phenolic metabolites identified, 10 compounds (mainly benzoic and 4-hydroxyvaleric acids) showed statistically significant increases (P < 0.05) after the wine intake. Also, the total phenolic metabolites content was significantly (P < 0.05) higher in the samples after the wine intake (625 ± 380 μg/g feces) in comparison to the samples before (358 ± 270 μg/g feces), and a tentative distribution of the volunteers into three groups could be established: <500, 500-1000, and >1000 μg/g feces. These results suggest that a different gut microbial capacity to metabolize wine polyphenols exists among the human population, as observed for polyphenols from other sources.

Daidzein-metabolizing phenotypes in relation to bone density and body composition among premenopausal women in the United States

BACKGROUND

Bone density has been suggested as a marker of cumulative hormone exposure. Small studies also suggest that patterns of daidzein metabolism may be related to hormone concentrations. To our knowledge, no studies in premenopausal women have compared bone density by daidzein-metabolizing phenotypes in the absence of a soy intervention.

OBJECTIVE

The objective was to evaluate the relationship between daidzein-metabolizing phenotypes [equol and O-desmethylangolensin (ODMA) production] and bone density and body composition in premenopausal women in the United States.

MATERIALS/METHODS

Two hundred and three women attended a clinic visit during which their bone density and body composition were measured by DXA, and 200 (99 %) provided a urine sample following a 3-day soy challenge. Samples were analyzed for isoflavones to determine daidzein-metabolizing phenotypes.

RESULTS

In adjusted analyses, there were no differences in hip, spine, femoral neck, or head bone mineral density (BMD) or body composition between producers and non-producers of either equol or ODMA (P > .05).

CONCLUSIONS

In this population of low-soy consuming premenopausal women, there were no associations between daidzein-metabolizing phenotypes and hip, spine, femoral neck, or head BMD or body composition, suggesting that these phenotypes per se do not influence premenopausal bone density or body composition.

Dietary ungerminated and germinated soybean supplementation improves bone mineralization and strength in growing male rats

It has been thought that soybean products rich in phytoestrogenic isoflavones are effective in promoting bone metabolism in ovariectomized rats. However, it is not clear if such an effect can be changed by germination of soybean and can be observed in growing males. The present study was undertaken to determine the effects of different concentrations of dietary ungerminated and germinated soybean (UGS and GS, respectively) on bone metabolism in young male rats. Forty-nine 6-week-old male Sprague-Dawley rats were assigned to seven dietary treatment groups: AIN 93G (control); control with UGS powder at 3% (UGS-L), 15% (UGS-M), or 30% (UGS-H); and control with GS powder at 3% (GS-L), 15% (GS-M), or 30% (GS-H). The biomarkers of bone metabolism (plasma and urinary Ca and P) and the physical properties and mineral content of bones were measured. Plasma osteocalcin and urinary deoxypyridinoline levels were not affected by soybean diets. The plasma P level was significantly elevated by dietary soybeans (P < .001). However, there was a negative correlation (r = -0.555) between plasma P level and dietary UGS level (P < .01). Between the UGS and GS groups, the P level of the GS-M group was significantly higher than that of the UGS-M group (P < .001). The tibial weight was decreased with low to medium doses of soybeans, but not with higher levels. Femoral bone strength was improved in the UGS-H, GS-M, and GS-H groups. The P contents of femoral and tibial bones were increased in all UGS groups as well as in GS-M and GS-H groups. In conclusion, soybean supplementation in young growing male rats improved bone mineralization and bone strength.