Aglycone Units Research Articles

Approaches to the synthesis of heterocyclic C-nucleosides.

This review is focused on the synthetic strategies to heterocyclic C-nucleosides and covers the literature from 2011 to 2021. The main attention is paid to the following three approaches: the direct C-C coupling of a carbohydrate moiety with a preformed aglycon unit, the construction of a (pseudo)sugar residue on a pre-formed aglycon, and the construction of an aglycon on a pre-formed (pseudo)sugar. In each Section, the literature data are categorized in terms of the size of aglycon from simple to complex, the advantages and drawbacks of the reviewed approaches are discussed.

Docking-based virtual screening, ADMET, and network pharmacology prediction of anthocyanidins against human alpha-amylase and alpha-glucosidase enzymes as potential antidiabetic agents

Diabetes mellitus (DM) characterized by high blood sugar concentration is a major global public health problem and untreated DM results in blindness, kidney failure, heart attack, stroke, and lower extremity amputation. In this structure-based drug design (SBDD) study, the potential inhibitory effects of twelve anthocyanidins (aglycon unit of anthocyanins) components on human pancreatic α-amylase and intestinal α-glucosidase enzymes were investigated using the molecular docking method and a novel approach developed by our research group was used to rank the global binding potentials of ligands to a series of different enzymes simultaneously. In addition, drug-likeness, absorption-distribution-metabolism-excretion-toxicity (ADMET) predictions, and intracellular target-component interaction network analyses of twelve anthocyanidin components were performed using the search tool for interactions of chemicals (STITCH). Petunidin, peonidin, and aurantinidin were determined as 'hit' phytochemicals according to the docking binding energy and relative binding capacity index (RBCI) analyses, whereas, based on the RBCI index, petunidin was found to be the most effective ligand in terms of binding capacity to both enzymes that play an important role in DM. The more accessible and large-volume active site of α-amylase compared to α-glucosidase caused petunidin to bind with higher affinity against α-amylase. Promisingly, petunidin did not violate any of the criteria for drug-likeness consisting of a combination of the Lipinski's rule of 5, Ghose and Veber filters, showed no cytochrome (CYP) P450 or hERG I-II inhibitory activity in the ADMET analysis, however, it was found to have a low gastrointestinal absorption profile. In intracellular target-component network analysis using the STITCH online platform, it was determined that petunidin did not show negative functional interactions with any enzyme in the human protein network. Considering these results, it is recommended that petunidin be advanced to further in vitro and in vivo assays as a potential α-amylase and α-glucosidase inhibitory agent in the treatment of DM. However, the intestinal absorption profile of petunidin must be enhanced by molecular optimization without compromising its pharmacological activity.

Structure Revision of the Lomaiviticins.

The lomaiviticins are dimeric genotoxic metabolites that contain unusual diazocyclopentadiene functional groups and 2-4 deoxyglycoside residues. Because only 6 of 19 carbon atoms in the monomeric aglycon unit are proton-attached, their structure determination by NMR spectroscopic analysis is difficult. Prior structure elucidation efforts established that the two halves of the lomaiviticins are joined by a single carbon-carbon bond appended to an oxidized cyclohexenone ring. This ring was believed to comprise a 4,5-dihydroxycyclohex-2-ene-1-one. The bridging bond was positioned at C6. This structure proposal has not been tested because no lomaiviticin has been prepared by total chemical synthesis or successfully analyzed by X-ray crystallography. Here, we disclose microED studies which establish that (-)-lomaiviticin C contains a 4,6-dihydroxy-cyclohex-2-ene-1-one residue, that the bridging carbon-carbon bond is located at C5, and that the orientation of the cyclohexenone ring and configuration of the secondary glycoside are reversed, relative to their original assignment. High-field (800 MHz) NMR analysis supports the revised assignment and suggests earlier efforts were misled by a combination of a near-zero 3JH4,H5 coupling constant and a 4JC,H coupling interpreted as a 3JC,H coupling. DFT calculations of the expected 13C chemical shifts and C-H coupling constants provide further robust support for the structure revision. Because the interconversion of lomaiviticins A, B, and C has been demonstrated, these findings apply to each isolate. These studies clarify the structures of this family of metabolites and underscore the power of microED analysis in natural product structure determination.

A Review on Saponin Biosynthesis and its Transcriptomic Resources in Medicinal Plants

Saponins are naturally occurring glycosides which are produced by various plant species with diverse biological properties. The surface-active properties of saponins differentiates them from other glycosides. They are classified mainly into steroid and triterpenoid glycosides based on the structure of hydrophobic aglycone unit. The synthesis of saponins and the genes involved in its biosynthesis can be identified by transcriptome profiling. Using high-throughput sequencing technologies, the steroid or triterpenoid saponin biosynthesis related genes have been discovered which can help boosting the molecular research in this biosynthetic pathway. This review mainly illustrates the importance of saponins and the transcriptome resources of important medicinal plants for identifying genes related to its biosynthesis. Furthermore, the significance of unexplored plants which are rich sources of saponins in future studies are also discussed in the current review.

Synthesis of Aryl or Heteroaryl C-Nucleosides by Direct Coupling of a Carbohydrate Moiety with a Preformed Aglycon Unit

C-Nucleosides have similar structure compared to native N-nucleosides, while the carbohydrate unit and the base in a C-nucleoside are connected through a carbon-carbon bond. Because they can also be recognized and utilized by enzymes associated with N-nucleosides in cells, C-nucleosides can inhibit enzyme-catalyzed synthesis or degradation of nucleic acids, thereby inhibiting the proliferation of viruses or cancer cells. C-Nucleoside synthesis has drawn much attention since the clinical application of the C-nucleoside drug remdesivir for the treatment of COVID-19. The direct coupling of a carbohydrate moiety with a preformed aglycon unit is an efficient synthetic approach to construct aryl or heteroaryl C-nucleoside. The synthetic methods of aryl or heteroaryl C-nucleosides in recent years are summarized from three main synthetic strategies: coupling of ribose derivatives with organometallic reagents, transition metal-catalyzed coupling of ribose derivatives with organometallic reagents, and acid-catalyzed Friedel-Crafts reaction of ribose derivatives. Each synthetic strategy is categorized in terms of sugar donor precursors, including hemiacetal riboses, ribonolactones, ribofuranosyl halides, glycal, and others. The mechanism of α or β product formation in these reactions are explained in detail as well. © 2021 Chinese Chemical Society & SIOC, CAS.

Novel Steroidal Glycosides from the Whole Plants of Helleborus foetidus.

Phytochemical analysis of the whole Helleborus foetidus plants identified 28 steroidal glycosides (1-28), including 20 novel spirostanol glycosides (1-20) and a novel furostanol glycoside (21). The structures of the newly identified compounds were elucidated by two-dimensional NMR spectroscopy and hydrolytic cleavage. Compounds 12, 13, and 15 were determined to be spirostanol trisdesmosides bearing sugar moieties at the C-1, -21, and -24 hydroxy groups of the aglycone unit. The isolated compounds were subsequently evaluated for cytotoxic activity against HL-60 human promyelocytic leukemia cells and A549 human lung carcinoma cells. In particular, 7 showed cytotoxic activity against the HL-60 and A549 cells, with IC50 values of 5.9 and 6.6 µM, respectively, whereas 19 was selectively cytotoxic to A549 cells with an IC50 value of 5.5 µM.

Evolvulins I and II, Resin Glycosides with a Trihydroxy Aglycone Unit from Evolvulus alsinoides.

Evolvulins I and II (1 and 2), representing a new class of resin glycosides with an unprecedented trihydroxy aglycone unit, 3S,11R,14R-trihydroxyhexadecanoic acid (4), were isolated from the whole plants of Evolvulus alsinoides. Their structures were thoroughly characterized by extensive spectroscopic analyses as well as chemical evidence. Compound 1 exhibited the most potent cytotoxic activity against MCF-7 cells, with an IC50 value of 3.12 μM.

Chlorination of Betacyanins in Several Hypochlorous Acid Systems.

This study presents a comparative evaluation of chlorination of betanin, betanidin, and neobetanin exposed to sodium hypochlorite and myeloperoxidase (MPO)/H2O2/Cl(-) systems. For betanin/betanidin, the chlorination takes place at the aglycone unit, but for neobetanin, no chlorinated products in the reaction mixtures can be detected. In the RP-HPLC system, monochloro-betanin/-betanidin were eluted earlier than their corresponding nonchlorinated substrates. An influence of Cl(-) concentration on betanin/betanidin chlorination efficiency in sodium hypochlorite and MPO systems was investigated. At pH 3-5, the yields of formed monochloro-betanin/-betanidin decrease dramatically at higher Cl(-) concentrations, indicating that generated Cl2 is not the chlorinating agent in the presence of sodium hypochlorite. The intriguing low activity of Cl2 in betanin/betanidin chlorination compared to HOCl and/or Cl2O can be explained by a special position of the attack by molecules of HOCl and/or Cl2O. In the MPO/H2O2/Cl(-) system, the highest efficiency of monochloro-betanin/-betanidin generation is observed at pH 5.

Structural characterization of flavonoid C- and O-glycosides in an extract of Adhatoda vasica leaves by liquid chromatography with quadrupole time-of-flight mass spectrometry.

Adhatoda vasica Nees is a well-known Ayurvedic medicinal plant, belonging to the family Acanthaceae. This study aims to seek identification and characterization of flavonoid C- and O-glycosides in the aqueous fraction of the plant leaves. A method was developed for simultaneous characterization of flavonoids and their glycosides using high-pressure liquid chromatography with quadrupole time-of-flight mass spectrometry (HPLC/ESI-QTOF-MS/MS). The chromatographic separation was carried on an Agilent Poroshell 120 EC-C18 column (4.6 × 150 mm, 2.7 µm) operated with 0.1% formic acid aqueous solution and methanol as the mobile phase. The fragmentations of the studied [M-H](-) ions of C-glycosides were shown to be cross-ring cleavages of the glycoside moiety [M-H-(60/90/120)](-) whereas O-glycosides were shown to eliminate the sugar moiety (Y0 (-) or [Y0 -H](-) ) from the aglycone unit; 6-C-glycosides exhibited [M-H-18](-) , a characteristic ion, and also a higher abundance of (0,3) X6 or 8 ions in comparison to 8-C glycosides; flavonoid 6,8-di-C-glycosides exhibited cross-ring cleavages of the sugar attached to the C-6 position preferentially. This method was successfully applied for analysis of flavonoids and their glycosides in Adhatoda vasica leaves. A total of 29 compounds were tentatively identified including 17 C-, nine O-glycosides and three flavonoids.

Biosynthesis of pyranonaphthoquinone polyketides reveals diverse strategies for enzymatic carbon–carbon bond formation

Pyranonaphthoquinones synthesized by Streptomyces bacteria via type II polyketide pathways are aromatic compounds build around a common three-ring structure, which is composed of pyran, quinone and benzene rings. Over the years, actinorhodin in particular has served as a model compound for studying the biosynthesis of aromatic polyketides, while some of the other metabolites such as granaticin, medermycin, frenolicin and alnumycin A have enabled comparative studies that complement our understanding how these complex biological systems function and have evolved. In addition, despite the similarity of the aglycone units, pyranonaphthoquinones in effect display remarkable diversity in tailoring reactions, which include numerous enzymatic carbon-carbon bond forming reactions. This review focuses on the current status of molecular genetic, biochemical and structural investigations on this intriguing family of natural products.

Antimicrobial Activity of the Seed Kernel and Leaf Extracts of Mangifera indica L. (Fam. Anacardiaceae) Against Escherichia coli

Mango [Mangifera indica L. (Fam. Anacardiaceae)], particularly the carabao mango, is widely endemic in the Philippines and its seed kernels and mature leaves have many purported folkloric uses and pharmacologic activities that function as antioxidant, antitussive, antiviral, among others which were linked to its primary constituent, mangiferin, a xanthone glycoside. However, there are a limited number of studies on the antimicrobial activity of the aforementioned variety of mango. Hence, this study was carried out to qualitatively determine their chemical constituents and their possible antimicrobial activity. The general procedure performed was of two distinct sets: the (i) characterization of the crude extract, and (ii) the bioassay-guided fractionation. Results showed that the hexane fraction of the seed kernel possessed antimicrobial activity which was inferred to be due to the aglycone unit of mangiferin. It is recommended that spectroscopic tests (i.e. UV, IR, NMR, etc.) be conducted for further isolation and characterization.

Effect of soy isoflavone supplementation on nitric oxide metabolism and blood pressure in menopausal women

Isoflavones, having chemical structures similar to estrogens, are believed to stimulate nitric oxide production and thus lower blood pressure. The efficacy of soy isoflavone supplementation to stimulate nitric oxide production and lower blood pressure in menopausal women with high normal blood pressure remains unknown. The objective was to test the effect of soy isoflavone supplementation on nitric oxide production and blood pressure in menopausal women with high normal blood pressure. A randomized, double-blind, parallel, placebo-controlled 6-wk trial was conducted to assess the effects of daily supplementation with 80 mg soy hypocotyl isoflavones (in aglycone units) on nitric oxide metabolism and blood pressure in 24 menopausal women with 12 women per group. Changes in nitric oxide metabolism were assessed via a primed, constant-infusion protocol with [15N]arginine and [13C]- and [2H]citrulline. Changes in blood pressure and associated vascular hemodynamics were assessed via office and 24-h ambulatory blood pressure monitoring, forearm blood flow, and indexes of arterial compliance. When compared with placebo and after control for pretreatment values, soy isoflavone supplementation had no effect on arginine flux, citrulline flux, nitric oxide synthesis, blood pressure, forearm blood flow, or estimates of arterial stiffness. Daily supplementation with 80 mg soy hypocotyl isoflavones over a 6-wk period had no effect on nitric oxide metabolism or blood pressure and associated vascular hemodynamics in menopausal women with high normal blood pressure.

Screening of glycoside isomers in P. scrophulariiflora using ionic liquid‐based ultrasonic‐assisted extraction and ultra‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

A powerful ionic liquid-based ultrasonic-assisted extraction (ILUAE) method combined with ultra-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC/ESI-QTOFMS(n) ) was employed in the rapid simultaneous screening of iridoid glycosides, phenylethanoid glycosides, and cucurbitacin glycosides from P. scrophulariiflora. The ILUAE procedure was optimized over several ultrasonic parameters, including the ultrasonic power, concentration of the ionic liquid, and solid-liquid ratio. A comparison with conventional heat-reflux extraction and regular UAE demonstrated that the optimized approach yielded a high extraction efficiency (Picroside I, 2.84%; Picroside II, 3.57%; 6-O-E-feruloyl catalpol, 2.20%) within a short extraction time of 30 min. Negative ion mode ESI-QTOFMS(2) analysis of the fragmentation reactions of the [M-H](-) ions was conducted to characterize the diagnostic ions related to the glycosyl moieties, aglycone units, and the type and substituted position of the ester groups. Interestingly, the positional isomers of the iridoid glycosides could be easily discriminated based on the characteristic ions. A total of 15 glycosides, including three groups of iridoid glycoside isomers and two groups of phenylethanoid glycoside isomers, were conveniently identified within 13.5 min. Moreover, 6'-O-vanilloyl catalpol was identified in P. scrophulariiflora for the first time. The method developed here was further validated by measuring the recovery, correlation coefficient (R(2) ), and reproducibility (RSD, n = 5) of three iridoid glycosides: 89.60%-109.02%, 0.9991-0.9998, and 0.93%-1.44%, respectively. This study demonstrated the capabilities of ILUAE combined with UPLC/ESI-QTOFMS(n) for the rapid screening of glycosides in P. scrophulariiflora. This method offers an approach to similar studies on other natural plants.

A review of acacic acid-type saponins from Leguminosae-Mimosoideae as potent cytotoxic and apoptosis inducing agents

The aim of this review is to highlight updated results on the biologically active saponins from Leguminosae-Mimosoideae. Acacic acid-type saponins (AATS), is a class of very complex glycosides possessing a common aglycon unit of the oleanane-type (acacic acid = 3β, 16α, 21β trihydroxy-olean-12-en-28 oic acid), having various oligosaccharide moieties at C-3 and C-28 and an acyl group at C-21. About sixty molecules of this type have been actively explored in recent years from Leguminosae family, from a chemical point of view and some fifty were reported to possess cancer related activities. These include cytotoxic/antitumor, immunomodulatory, antimutagenic, and apoptosis inducing properties and appear to depend on the acylation and esterification by different moieties at C-21 and C-28 of the acacic acid-type aglycone. One can observe that the (6S) configuration of the outer monoterpenyl moiety (MT) seems more potent in mediating high cytotoxicity than its (6R) isomer. Furthermore, the trisaccharide moiety {β-d-Xylopyranosyl-(1→2)-β-d-Fucopyranosyl-(1→6)- N-Acetamido 2-β-d-Glucopyranosyl-} at C-3, the tetrasaccharide moiety {β-d-Glucopyranosyl-(1→3)-[α-L-Arabinofuranosyl-(1→4)]-α-l-Rhamnopyranosyl-(1→2)-β-d-Glucopyranosyl} at C-28 of the aglycone, and the inner MT hydroxylated at its C-9, having a (6S) configuration can be important substituent patterns for the induction of apoptosis of AATS. Because of their interesting cytotoxic/apoptosis inducing activity, some AATS can be useful in the search for new potential antitumor agents from Fabaceae. Furthermore, the sequence 28-O-{Glc-(1→3)-[Araf-(1→4)]-Rha-(1→2)-Glc-Acacic acid}, often encountered in the genera Acacia, Albizia, Archidendron, and Pithecellobium may represent a chemotaxonomic marker of the Mimosoideae subfamily.

Rapid Identification of Calotropagenin Glycosides Using High‐Performance Liquid Chromatography Electrospray Ionisation Tandem Mass Spectrometry

Cardiac glycosides in Calotropis procera have therapeutic use as inhibitors of Na⁺/K⁺-ATPase to regulate heart contractions. A large amount of research attention has been received by these compounds towards their identification and structural characterisation. In order to achieve rapid identification of cardiac glycosides in phytochemical extracts a liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed involving metal cationisation by post-column addition of alkali salts for the unambiguous determination of their molecular weights. Identification of cardiac glycosides in Calotropis procera leaf extract. Calotropagenin and its 10 glycosides were unambiguously identified. The daughter ions at m/z 387, 369, 359, 351, 341 and 323 in their MS/MS spectra were attributed to the calotropagenin aglycone unit. High performance liquid chromatography in combination with electrospray ionization tandem mass spectrometry involving metal cationisation by post column addition of alkali salts was successfully utilised for the rapid identification of calotropagenin glycosides/derivatives in Calotropis procera extract.

Diet and Paraoxonase 1 Enzymatic Activity in Diabetic Foot Patients from Romania and Belgium: Favorable Association of High Flavonoid Dietary Intake with Arylesterase Activity

Background/Aims: The antiatherosclerotic enzyme paraoxonase (PON1) is affected by disease and lifestyle. We investigated the impact of diet in diabetic foot patients from 2 European countries. Methods: Dietary intake and serum PON1 activity, using as substrate paraoxon (paraoxonase) or phenylacetate (arylesterase), were assessed in patients from Bucharest (n = 40) and Antwerp (n = 30) and in 34 healthy controls. Results: The diabetic patients had lower paraoxonase and arylesterase activities than the controls. Arylesterase was lowest in the Bucharest patients, 116 ± 42 U/ml, versus 141 ± 43 and 184 ± 49 U/ml in the Antwerp patients and controls, respectively (p < 0.0005). The Bucharest patients had worse glycemic control, higher blood pressure, lower HDL cholesterol and a diet richer in cholesterol and poorer in monounsaturated fats and fish. In contrast, their median intake of vitamins E and C, folic acid and flavonoids was higher, 82 mg (range: 4–259 mg), versus 28 mg (range: 5–169 mg) aglycone units in Antwerp (p = 0.005). Flavonoid intake predicted arylesterase independently of HDL cholesterol, region and sex (β = 0.27; p = 0.03), and patients with high intake achieved normal levels of arylesterase (30.1 ± 10.0 U/µmol in the highest versus 21.0 ± 8.2 U/µmol total cholesterol in the lowest tertile; p = 0.02). Conclusion: A flavonoid-rich diet is positively associated with PON1 arylesterase activity in diabetic foot patients.

Soy isoflavonoid effects on endogenous estrogen metabolism in postmenopausal female monkeys

Endogenous estrogens are important determinants of breast cancer risk in postmenopausal women. In this study we evaluated the effects of dietary soy isoflavonoids on endogenous estrogen metabolism in a postmenopausal primate model. Ovariectomized female cynomolgus monkeys were randomized to receive one of three diets for 36 months: (i) isoflavonoid-depleted soy protein isolate (SPI-) (n = 29); (ii) soy protein isolate with 129 mg isoflavonoids/1800 kcal diet (8.6 mg isoflavonoids/kg body weight (BW), expressed in aglycone units) (SPI+) (n = 29) or (iii) isoflavonoid-depleted soy protein isolate with conjugated equine estrogens (CEE) at a dose of 0.625 mg/1800 kcal diet (0.042 mg CEE/kg BW) (n = 30). Mean plasma isoflavonoid concentrations in the SPI+ group were 946.9 +/- 135.9 nmol/l, and equol was the primary circulating isoflavonoid (549.7 +/- 61.6 nmol/l). The SPI+ diet resulted in lower serum estrone (E(1)) after 29 (-26%, P = 0.03) and 34 months (-21%, P = 0.04) compared to the SPI- diet, while urinary 2-hydroxyestrone (P = 0.005) and the 2 to 16alpha-hydroxyestrone ratio (P < 0.0001) were markedly higher in the SPI+ group compared to SPI-. Isoflavonoid treatment did not significantly alter gene markers of estrogen metabolism or estrogen receptor agonist activity in breast tissue. Within the SPI+ group, higher concentrations of serum equol (but not daidzein or genistein) corresponded to significantly lower serum E(1), mammary gland epithelial area and uterine weight (P < 0.01 for all). These findings suggest that long-term exposure to soy isoflavonoids, equol in particular, may facilitate endogenous estrogen clearance and catabolism to more benign 2-hydroxylated metabolites.

Growth responsiveness of murine DMBA-induced salivary tumors to a soy protein–based diet rich in isoflavones

Salivary glands are sex hormone–dependent organs, with structure, function and tumor behavior regulated in part by steroid hormones. Soy protein contains isoflavones that have weak estrogenic activity. These compounds are hypothesized to play a role in cancer protection, especially in breast and prostate. The objective of this study was to determine the responsiveness of murine salivary tumors to a soy protein–based diet rich in isoflavones. Fifty 10-week-old BALB/c mice of both sexes were used. Fifteen males were assigned to casein treatment (C, control), and 16 males and 19 females to soy protein (SP, 2.28 mg isoflavones as aglycone units per gram protein). In experiment 1 (EXP 1), we tested the effect of the diet in males, and in experiment 2 (EXP 2), we examined the effect of sex on response to SP. After 2 weeks, tumors were induced by 9,10-dimethyl-1,2-benzanthracene. The animals were killed 13 weeks later, and body weight, in vivo tumor diameter (weeks 1, 6, and 11 of evolution), gland and tumor volumes, and tumor remission were evaluated. In EXP 1, males on SP had higher tumor volumes compared with those on C; however, this difference was not statistically significant. Tumor remission did not differ by treatment. In EXP 2, tumors were different in male and female mice fed the SP diet. Males developed bigger tumors than females. No sex differences were found in tumor remission. This study demonstrated a differential response to an SP-based diet rich in isoflavones, in female mice as compared with males.

Soy protein and bone mineral density in older men and women: A randomized trial

Objective Test the hypothesis that soy isoflavone supplementation preserves bone mineral density (BMD) in men and women. Methods We conducted a controlled, parallel-arm, double-blinded trial with 145 participants, 50–80 years, with random assignment to soy beverage daily for 12 months. Active treatment (+ISO) received soy protein containing 83 mg isoflavones (45.6 mg genistein, 31.7 mg daidzein), aglycone units; the comparison group (−ISO) received soy protein containing 3 mg isoflavones. We measured BMD using dual-energy X-ray absorptiometry at the total hip and posterior–anterior spine (L1–L4) at baseline in 22 women and 123 men, and at 12 months in 13 women and 98 men. We used linear mixed models to test for an isoflavone effect on percentage BMD change from baseline in spine and hip. Results Among all participants, mean percent change in spine BMD (±S.E.) was 0.16 ± 0.44 in −ISO ( P = 0.10) at 12 months. Treatment effects on spine BMD were significantly greater in women than men ( P = 0.01). At 12 months, in women, mean percent change was 0.58 ± 0.70 in +ISO and −1.84 ± 0.86 in −ISO ( P = 0.05); among men it was 1.32 ± 0.53 in +ISO and 0.31 ± 0.48 in −ISO ( P = 0.16). By comparison, percent change in hip BMD was similar in the treatment groups, and was not different between men and women. Mean percent change in hip BMD from baseline to 12 months was 0.54 ± 0.38 in +ISO and −0.13 ± 0.36 in −ISO ( P = 0.20) among all participants. Conclusions Soy protein containing isoflavones showed a modest benefit in preserving spine, but not hip BMD in older women.

Effects of High-Dose Soy Isoflavones and Equol on Reproductive Tissues in Female Cynomolgus Monkeys1

Soy isoflavonoids have well-established estrogenic properties in cell culture and rodent models, raising concerns that high isoflavonoid intake may promote development of uterine and breast cancers. To address this concern we evaluated the effects of high-dose isoflavonoid supplements on reproductive tissues in a postmenopausal primate model. Thirty adult female ovariectomized monkeys (Macaca fascicularis) were randomized to receive a control diet 1) alone, 2) with 509 mg/day of the soy isoflavones genistein and daidzein (IF), or 3) with 1020 mg/day of racemic equol (EQ), an isoflavan, for approximately 1 mo. Doses are expressed in aglycone units as calorically scaled human equivalents. Total serum isoflavonoid levels 4 h postfeeding were <20 nmol/L, 2570.7 nmol/L, and 6944.8 nmol/L for control, IF, and EQ groups, respectively. Equol was the predominant serum isoflavonoid in both IF (72.5%) and EQ (99.7%) groups. Aglycones represented 0.9% (IF) and 0.5% (EQ) of total serum isoflavonoids. Histologically, uteri and mammary glands were diffusely atrophic in all groups. Uterine weight, endometrial thickness, glandular area, and epithelial proliferation in the uterus were not significantly different among treatment groups (ANOVA P > 0.1 for all). Endometrial progesterone receptor gene expression was significantly increased in the IF group (P = 0.02), while protein expression was not altered (ANOVA P > 0.1). Within the mammary gland, proliferation and indicators of estrogen exposure did not differ among treatment groups (ANOVA P > 0.1 for all). These findings indicate that high doses of dietary soy isoflavonoids have minimal uterotrophic or mammotrophic effects in an established primate model.