Lack of sufficient information on the specificity and selectivity of commercial phytoestrogens preparations for therapeutic purposes

Assessment of estrogenic potential from exudates of microcystin-producing and non-microcystin-producing Microcystis by metabolomics, machine learning and E-screen assay

Cyanobacterial blooms, often dominated by Microcystis aeruginosa, are capable of producing estrogenic effects. It is important to identify specific estrogenic compounds produced by cyanobacteria, though this can prove challenging owing to the complexity of exudate mixtures. In this study, we used untargeted metabolomics to compare components of exudates from microcystin-producing and non-microcystin-producing M. aeruginosa strains that differed with respect to their ability to produce microcystins, and across two growth phases. We identified 416 chemicals and found that the two strains produced similar components, mainly organoheterocyclic compounds (20.2%), organic acids and derivatives (17.3%), phenylpropanoids and polyketides (12.7%), benzenoids (12.0%), lipids and lipid-like molecules (11.5%), and organic oxygen compounds (10.1%). We then predicted estrogenic compounds from this group using random forest machine learning. Six compounds (daidzin, biochanin A, phenylethylamine, rhein, o-Cresol, and arbutin) belonging to phenylpropanoids and polyketides (3), benzenoids (2), and organic oxygen compound (1) were tested and exhibited estrogenic potency based upon the E-screen assay. This study confirmed that both Microcystis strains produce exudates that contain compounds with estrogenic properties, a growing concern in cyanobacteria management.

Computational Approaches for the Discovery of GPER Targeting Compounds

Estrogens exert a panel of biological activities mainly through the estrogen receptors α and β, which belong to the nuclear receptor superfamily. Diverse studies have shown that the G protein-coupled estrogen receptor 1 (GPER, previously known as GPR30) also mediates the multifaceted effects of estrogens in numerous pathophysiological events, including neurodegenerative, immune, metabolic, and cardiovascular disorders and the progression of different types of cancer. In particular, GPER is implicated in hormone-sensitive tumors, albeit diverse issues remain to be deeply investigated. As such, this receptor may represent an appealing target for therapeutics in different diseases. The yet unavailable complete GPER crystallographic structure, and its relatively low sequence similarity with the other members of the G protein-coupled receptor (GPCR) family, hamper the possibility to discover compounds able to modulate GPER activity. Consequently, a reliable molecular model of this receptor is required for the design of suitable ligands. To date, convergent approaches involving structure-based drug design and virtual ligand screening have led to the identification of several GPER selective ligands, thus providing important information regarding its mode of action and function. In this survey, we summarize results obtained through computer-aided techniques devoted to the assessment of GPER ligands toward their usefulness in innovative treatments of different diseases.

Effects of Isolated Isoflavones Intake on Health

BACKGROUND

Isoflavones are naturally occurring flavonoids, commonly found in the food consumed for centuries in the East-Asian population, characterized by a structure able to exert nonsteroidal estrogen-like activity on human cells. They have attracted researcher interest all around the word, following the results obtained in epidemiological and clinical studies. The involvement of isoflavones and their metabolites in various biological processes suggests that they can influence several metabolic pathways and can influence the gene expression at epigenetic level, involving effects that probably are due to early life exposure. They show positive health effects on several diseases, especially in the prevention of coronary heart and neurological diseases, hormone-related cancers, osteoporosis, and postmenopausal symptoms.

METHODS

We have performed a critical evaluation of available literature trough a structured search of bibliographic databases about isoflavones health promoting properties, risk assessment and mechanisms of action. In addition, we supplied useful information on their biochemical properties, sources and bioavailability.

RESULTS

Although these molecules have been the subjects of numerous researches, their role for the wellness of the human organism remains controversial. Moreover, there are substantial inconsistencies between the results obtained by epidemiologic studies conducted on Eastern population, which found high health promoting properties, and Western clinical trials, which found much less positive effects.

CONCLUSION

Further epidemiologic studies and well-designed prospective human studies are to determine the beneficial effects of isoflavones exposure, as well as establishing its safe therapeutic.

Safety and feasibility of estrogen receptor-β targeted phytoSERM formulation for menopausal symptoms: phase 1b/2a randomized clinical trial

OBJECTIVE

PhytoSERM is a formulation of genistein, daidzein, and S-equol that has an 83-fold selective affinity for estrogen receptor-β (ERβ); and may enhance neuron function and estrogenic mechanisms in the brain without having peripheral estrogenic activity.

METHODS

We conducted an overarching, two-stage, dose-ranging, double-blinded, randomized, placebo-controlled trial of 12 weeks duration comparing 50 and 100 mg/d of phytoSERM with placebo for noncognitively impaired, perimenopausal women aged 45 to 60, with intact uteri and ovaries, with at least one cognitive complaint, and one vasomotor-related symptom. Primary objectives were to assess safety and tolerability of a 50 and 100 mg daily dose; and, secondly, to evaluate potential indicators of efficacy on cognition and vasomotor symptoms over 4 and 12 weeks, and using an embedded, 4-week, 2-period, placebo-controlled crossover trial for a subset of participants.

RESULTS

Seventy-one women were randomized to treatment; 70 were evaluated at 4 weeks; 12 were entered into the crossover study; 5 did not complete 12 weeks. Reasons for discontinuation were withdrawal of consent (n = 1) and lost to follow-up (n = 4). Adverse events occurred in 16.7% (n = 4) placebo, 39.1% (n = 9) 50 mg/d, and 29.2% (n = 7) 100 mg/d treated participants; 85% were mild and none was severe. Vaginal bleeding occurred in 0, placebo; 1, 50 mg; and 3, 100 mg/d participants.

CONCLUSIONS

The phytoSERM formulation was well tolerated at 50 and 100 mg daily doses. Based on safety outcomes, vaginal bleeding at the 100 mg dose, and vasomotor symptoms and cognitive outcomes at 12 weeks, a daily dose of 50 mg was considered preferable for a phase 2 efficacy trial.

Scientific Papers and Patents on Substances with Unproven Effects. Part 2

Several examples are discussed in this review, where substances without proven effects were proposed for practical use within the scope of evidence-based medicines. The following is discussed here: generalizations of the hormesis concept and its use in support of homeopathy; phytoestrogens and soy products potentially having feminizing effects; glycosaminoglycans for the treatment of osteoarthritis and possibilities of their replacement by diet modifications; flavonoids recommended for the treatment of chronic venous insufficiency and varicose veins; acetylcysteine as a mucolytic agent and its questionable efficiency especially by an oral intake; stem cells and cell therapies. In conclusion, placebo therapies can be beneficial and ethically justifiable but it is not a sufficient reason to publish biased information. Importantly, placebo must be devoid of adverse effects, otherwise, it is named pseudo-placebo. Therapeutic methods with unproven effects should be tested in high-quality research shielded from the funding bias. Some issues discussed in this review are not entirely clear, and the arguments provided here can initiate a constructive discussion.

Therapeutic Perspectives of 8-Prenylnaringenin, a Potent Phytoestrogen from Hops

Hop (Humulus lupulus L.), as a key ingredient for beer brewing, is also a source of many biologically active molecules. A notable compound, 8-prenylnaringenin (8-PN), structurally belonging to the group of prenylated flavonoids, was shown to be a potent phytoestrogen, and thus, became the topic of active research. Here, we overview the pharmacological properties of 8-PN and its therapeutic opportunities. Due to its estrogenic effects, administration of 8-PN represents a novel therapeutic approach to the treatment of menopausal and post-menopausal symptoms that occur as a consequence of a progressive decline in hormone levels in women. Application of 8-PN in the treatment of menopause has been clinically examined with promising results. Other activities that have already been assessed include the potential to prevent bone-resorption or inhibition of tumor growth. On the other hand, the use of phytoestrogens is frequently questioned regarding possible adverse effects associated with long-term consumption. In conclusion, we emphasize the implications of using 8-PN in future treatments of menopausal and post-menopausal symptoms, including the need for precise evidence and further investigations to define the safety risks related to its therapeutic use.

Effects of a phyto complex on well-being of climacteric women

AIM

The aim of this study was to assess the effects of a phyto complex on menopausal symptoms.

MATERIAL AND METHODS

A total of 151 women aged 42-67 years were enrolled. They were in spontaneous or surgical menopause by at least 12 months, reporting symptoms referable to the climacteric syndrome. Two validated and standardized tests were given to the whole sample at the entrance of the study (T0) and after 6 months of treatment (T6): the Greene Climacteric Scale (GCS) and the Beck Depression Inventory (BDI). Interim evaluations were carried out at 1-3 months (T1 and T3) on five symptoms selected from the GCS. The phyto complex was given to each enrolled woman, from the T0 to T6 time-points, for a total of 180 days.

RESULTS

At the T0 time-point, the average scores were: GCS, 28.98 (standard deviation [SD] ± 10.71); BDI, 14.48 (SD ± 6.5). At the T1 time-point, five parameters of the GCS were assessed with a reduction of 36.25% in symptoms (5.69, SD ± 3.53). At the T6 time-point the assessment was completed: average GCS results were 11.54 (SD ± 8.01) with a 60.17% improvement; and average BDI results were 6.11 (SD ± 4.6) with a 58.91% improvement in the depressive symptoms.

CONCLUSIONS

The phyto complex under consideration is an effective tool to counter, in a quick and long-lasting manner, the most common and nagging symptoms of the climacteric syndrome, such as hot flushes, insomnia and depression.

Soy and phytoestrogens: possible side effects

Phytoestrogens are present in certain edible plants being most abundant in soy; they are structurally and functionally analogous to the estrogens. Phytoestrogens have been applied for compensation of hormone deficiency in the menopause. At the same time, soy products are used in infant food and other foodstuffs. Furthermore, soy is applied as animal fodder, so that residual phytoestrogens and their active metabolites such as equol can remain in meat and influence the hormonal balance of the consumers. There have been only singular reports on modified gender-related behavior or feminization in humans in consequence of soy consumption. In animals, the intake of phytoestrogens was reported to impact fertility, sexual development and behavior. Feminizing effects in humans can be subtle and identifiable only statistically in large populations.

Interactions of isoflavones and other plant derived estrogens with estrogen receptors for prevention and treatment of breast cancer-considerations concerning related efficacy and safety

Phytoestrogens are natural endocrine disruptors that interfere with estrogenic pathways. They insert directly within the hormone-binding domain of ERα and β, with a preference for the β isoform of which the concentration predominates in the normal mammary epithelium. Since ERβ antagonizes the growth promoting effect of ERα, which is mainly expressed in estrogen-sensitive tumor cells, a potential protective action against breast cancer incidence has been ascribed to phytoestrogens. The fact that Asian women living in far-east countries who consume isoflavone-rich food are less subjected to breast cancer emergence than their congeners in the USA as well as Caucasian women has been advocated to justify such a concept. Overview of data concerning the mechanism of action phytoestrogens reveals that such a view is an oversimplification: Such compounds interfere with a huge panel of regulatory proteins, giving rise to both promoting and antagonizing carcinogenic effects. Moreover, various physiological and pathological factors able to amplify these effects are not often sufficiently taken into account, which increases the difficulty to interpret data. Nevertheless, this overview of data established that chemical structures and concentrations modulate such effects: at the micromolar level, isoflavones activate ERα-mediated transcription and breast cancer cell proliferation while flavones fail to induce any significant promoting effects. At higher doses, both classes of compounds may display an antitumor activity. Reasons for such distinct behaviors as well as their potential impact in therapeutic applications are analyzed here. Ability of isoflavones and flavones to antagonize the association of calmodulin to ERα, which is required for its enhanced transcriptional activity is evoked to justify the antitumor activity ascribed to some flavones. Finally, a suspicion that peculiar classes of phytoestrogens may adopt a SERM-like conformation is addressed in a context of selection and synthesis of compounds with non-equivocal therapeutic value. This article is part of a Special Issue entitled "Phytoestrogens".

Effect of formononetin on mechanical properties and chemical composition of bones in rats with ovariectomy-induced osteoporosis

Formononetin is a naturally occurring isoflavone, which can be found in low concentrations in many dietary products, but the greatest sources of this substance are Astragalus membranaceus, Trifolium pratense, Glycyrrhiza glabra, and Pueraria lobata, which all belong to Fabaceae family. Due to its structural similarity to 17β-estradiol, it can mimic estradiol's effect and therefore is considered as a “phytoestrogen.” The aim of this study was to examine the effect of formononetin on mechanical properties and chemical composition of bones in rats with ovariectomy-induced osteoporosis. 12-week-old female rats were divided into 4 groups: sham-operated, ovariectomized, ovariectomized treated with estradiol (0.2 mg/kg) and ovariectomized treated with formononetin (10 mg/kg). Analyzed substances were administered orally for 4 weeks. Ovariectomy caused osteoporotic changes, which can be observed in bone biomechanical features (decrease of maximum load and fracture load and increase of displacements for maximum and fracture loads) and bone chemical composition (increase of water and organic fraction content, while a decrease of minerals takes place). Supplementation with formononetin resulted in slightly enhanced bone mechanical properties and bone chemistry improvement (significantly lower water content and insignificantly higher mineral fraction content). To summarize, administration of formononetin to ovariectomized rats shows beneficial effect on bone biomechanical features and chemistry; thus, it can prevent osteoporosis development.

Effects of Extracts from Trifolium medium L. and Trifolium pratense L. on Development of Estrogen Deficiency-Induced Osteoporosis in Rats

Some plant species belonging to Trifolium L. genus are a source of isoflavones considered to exert phytoestrogenic activities. The aim of the present study was to examine the effects of standardized extract obtained from aerial parts of Trifolium medium L., in comparison with the extract of Trifolium pratense L., on the development of estrogen deficiency-induced osteoporosis in rats. Both Trifolium extracts, at doses corresponding to 10 and 20 mg/kg of isoflavone aglycones daily, or estradiol (0.2 mg/kg daily), were administered orally to ovariectomized (OVX) rats for 4 weeks. Serum bone turnover markers, bone mass, mineralization, and mechanical properties were studied. In OVX control rats, mechanical properties of the tibial metaphysis and femoral neck were strongly worsened in comparison with sham-operated control rats, and those of femoral diaphysis were unaffected. Estradiol counteracted the worsening of the tibial strength and increases in bone turnover markers. Both extracts significantly increased the strength of the femoral diaphysis and calcium and phosphorus content in the bone mineral, but only T. pratense extract increased the strength of the tibial metaphysis. In conclusion, effects of both Trifolium extracts differed from those of estradiol. It is possible that other than isoflavone extract constituents contributed to their skeletal effects.

Pomegranate seed oil in women with menopausal symptoms: a prospective randomized, placebo-controlled, double-blinded trial

OBJECTIVE

The aim of this study was to investigate the potential effects of pomegranate seed oil (PGS) on menopausal symptoms.

METHODS

The prospective randomized, placebo-controlled, double-blinded trial was completed by 81 postmenopausal women, who received two daily doses of either 30 mg PGS containing 127 μg of steroidal phytoestrogens per dose or a placebo for 12 weeks. The participants reported their number of hot flashes and completed the Menopause Rating Scale II at baseline and at weeks 4, 8, 12, and 24. At baseline and after 12 weeks, hormonal status was determined.

RESULTS

After 12 weeks of treatment, PGS reduced the number of hot flashes per day by 4.3 (38.7%), whereas placebo reduced it by 2.5 (25.6%). Both groups were significant compared with baseline, but the treated group was not significant compared with the placebo group (P = 0.17). After 24 weeks, the treated group showed a mean of 7.1 (interquartile range, 4.0) hot flashes per day compared with the placebo group with a mean of 8.8 (interquartile range, 5.0; P = 0.02). Although the overall sum score of the Menopause Rating Scale II parameters at week 12 decreased in the treated group from 16.0 to 9.0 at week 12 and in the placebo group from 18.0 to 14.5 (P = 0.08), the sum score of the vegetative somatic symptoms subgroup decreased strongly versus placebo (P < 0.03), attributable mainly to an improvement in sleeping disorders. PGS did not affect the hormone status, and no adverse effects were reported.

CONCLUSIONS

In postmenopausal women, PGS does not significantly reduce hot flashes within a 12-week observation period, but further studies are needed to investigate the long-term effect.

The effect of red clover isoflavone supplementation over vasomotor and menopausal symptoms in postmenopausal women

OBJECTIVE

To evaluate the effect of red clover isoflavone supplementation over vasomotor and overall menopausal symptoms in postmenopausal women.

METHODS

One hundred and nine postmenopausal women aged 40 or more were assigned to randomly receive either two daily capsules of the active compound (80 mg red clover isoflavones, Group A) or placebo of equal appearance (Group B) for a 90-day period. After a washout period of 7 days, medication was crossed over and taken for 90 days more. Daily hot flush and night sweat frequency and overall menopausal symptom intensity (Kupperman Index) were measured at baseline, 90, 97 and 187 days.

RESULTS

Daily hot flush/night sweat frequency and Kupperman Index values were similar in both studied groups at baseline. All indices significantly decreased after red clover phase in Group A, corresponding, respectively to a 73.5%, 72.2% and 75.4% average decrement. These decrements were significantly higher than those observed for Group B after placebo phase (8.2%, 0.9% and 6.7% respectively). In Group A, after washout and placebo phases all values significantly increased. In Group B, all indices remained similar after placebo and washout phases, however significantly dropping after red clover treatment. These values were also significantly lower than those observed in Group A after placebo phase. No side effects were encountered after treatment with the active compound or placebo.

CONCLUSION

Red clover isoflavone supplementation was more effective than placebo in reducing daily vasomotor frequency and overall menopausal intensity in postmenopausal women.

A critical view of the effects of phytoestrogens on hot flashes and breast cancer risk

The increased risk of breast cancer recently observed with some specific estro-progestin associations has raised concerns about the harmful effects of menopausal hormone replacement therapy (HRT). It has been proposed that phytoestrogens (PEs), which have a similar chemical structure to estrogens, could be used as HRT. The main selling points of these preparations concern the management of hot flashes and their potential beneficial effects on breast tissue. In this review, we will address the effects of PE on hot flashes and breast cancer risk as well as the questions raised on a chemical point of view. We conclude that the efficacy of a PE rich diet or nutritional supplements is not clearly established. The use of PE as an alternative for HRT cannot be advocated for now, due to insufficient and conflicting data on efficacy and safety. Moreover, due to the hormone dependence of breast cancer, PE use must be contraindicated in breast cancer survivors.