Structure-Activity Relationship of Phytoestrogen Analogs as ERα/β Agonists with Neuroprotective Activities

Antidepressant-like effects of the Punica granatum and citalopram combination are associated with structural changes in dendritic spines of granule cells in the dentate gyrus of rats

Introduction: Natural products such as phytoestrogens-enriched foods or supplements have been considered as an alternative therapy to reduce depressive symptoms associated with menopause. It is known that the aqueous extract of Punica granatum (AE-PG) exerts antidepressant-like effects by activating β-estrogen receptors and facilitates the antidepressant response of the clinical drug citalopram (CIT). However, the effects on neuroplasticity are unknown. Objectvie investigated the antidepressant-like response of combining AE-PG and CIT at sub-optimal doses, analyzing their effects on the formation and maturation of dendrite spines in granule cells as well as on the dendrite complexity. Methods: Ovariectomized Wistar rats (3-month-old) were randomly assigned to one of the following groups: A) control (saline solution as vehicle of CIT and AE-PG, B) AE-PG at a sub-threshold dose (vehicle of CIT plus AE-PG at 0.125 mg/kg), C) CIT at a sub-threshold dose (0.77 mg/kg plus vehicle of AE-PG), and D) a combination of CIT plus AE-PG (0.125 mg/kg and 0.77 mg/kg, respectively). All rats were treated intraperitoneally for 14 days. Antidepressant-like effects were evaluated using the force swimming test test (FST). The complexity of dendrites and the number and morphology of dendrite spines of neurons were assessed in the dentate gyrus after Golgi-Cox impregnation. The expressions of the mature brain-derived neurotrophic factor (mBDNF) in plasma and of mBDNF and synaptophysin in the hippocampus, as markers of synaptogenesis, were also determined. Results: Administration of CIT combined with AE-PG, but not alone, induced a significant antidepressant-like effect in the FST with an increase in the dendritic complexity and the number of dendritic spines in the dentate gyrus (DG) of the hippocampus, revealed by the thin and stubby categories of neurons at the granular cell layer. At the same time, an increase of mBDNF and synaptophysin expression was observed in the hippocampus of rats that received the combination of AE-PG and CIT.

Priority list of potential endocrine-disrupting chemicals in food chemical contaminants: a docking study and in vitro/epidemiological evidence integration

Diet is an important exposure route of endocrine-disrupting chemicals (EDCs), but many unfiltered potential EDCs remain in food. The in silico prediction of EDCs is a popular method for preliminary screening. Potential EDCs in food were screened using Endocrine Disruptome, an open-source platform for inverse docking, to predict the binding probabilities of 587 food chemical contaminants with 18 human nuclear hormone receptor (NHR) conformations. In total, 25 contaminants were bound to multiple NHRs such as oestrogen receptor α/β and androgen receptor. These 25 compounds mainly include pesticides and per- and polyfluoroalkyl substances (PFASs). The prediction results were validated with the in vitro data. The structural features and the crucial amino acid residues of the four NHRs were also validated based on previous literature. The findings indicate that the screening has good prediction efficiency. In addition, the epidemic evidence about endocrine interference of PFASs in food on children was further validated through this screening. This study provides preliminary screening results for EDCs in food and a priority list for in vitro and in vivo research.

Gut Microbiota-Assisted Synthesis, Cellular Interactions and Synergistic Perspectives of Equol as a Potent Anticancer Isoflavone

It is well known that, historically, plants have been an important resource of anticancer agents, providing several clinically approved drugs. Numerous preclinical studies have shown a strong anticancer potential of structurally different phytochemicals, including polyphenolic constituents of plants, flavonoids. In this review article, suppressing effects of equol in different carcinogenesis models are unraveled, highlighting the mechanisms involved in these anticancer activities. Among flavonoids, daidzein is a well-known isoflavone occurring in soybeans and soy products. In a certain part of population, this soy isoflavone is decomposed to equol under the action of gut microflora. Somewhat surprisingly, this degradation product has been shown to be more bioactive than its precursor daidzein, revealing a strong and multifaceted anticancer potential. In this way, it is important to bear in mind that the metabolic conversion of plant flavonoids might lead to products that are even more efficient than the parent compounds themselves, definitely deserving further studies.

Neuroprotective effects of tetrahydroxystilbene glucoside against rotenone-induced toxicity in PC12 cells

To investigate the mechanism of the protective effect of tetrahydroxystilbene glucoside (TSG) on nerve cells, an injury model induced by rotenone in PC12 cells was constructed. Cell viability was detected by using CCK8 assay. Apoptosis was detected by using flow cytometry. The mitochondrial membrane potential (MMP) was detected by using the fluorescent probe JC-1. Generation of reactive oxygen species (ROS) in PC12 cells was determined using the CM-H₂DCFDA probe. Protein expression in PC12 cells was detected using western blotting. The results showed that TSG (20-100 μM) attenuated the cytotoxic effects of rotenone on PC12 cells. TSG pretreatment attenuated the apoptosis rate, the degradation of PARP and the activation of cleaved caspase 3, which was induced by rotenone. TSG can significantly reduce the effect of rotenone on the reduction of MMP and the expression of cytoC in the cytosolic fraction. TSG attenuated rotenone-induced de-phosphorylation and mitochondrial translocation of cofilin, as well as rotenone-induced accumulation of ROS. The western blot results showed that ROT could decrease the expression level of p-GSK-3β and p-AKT, and TSG could weaken these effects of rotenone. In addition, TSG increased the expression level of Nrf2 in the nuclear fraction. These results suggest that TSG could protect PC12 cells against rotenone through multiple pathways. Thus, TSG has the potential to become a novel neuroprotective agent.

The potential anti-amyloidogenic candidate, SPA1413, for Alzheimer's disease

BACKGROUND AND PURPOSE

Recently, isoflavone derivatives have been shown to have neuroprotective effects against neurological disorders. For instance, genistein attenuated the neuroinflammation and amyloid-β accumulation in Alzheimer's disease animal models, suggesting the potential for use to prevent and treat Alzheimer's disease.

EXPERIMENTAL APPROACH

Here, 50 compounds, including isoflavone derivatives, were constructed and screened for the inhibitory effects on amyloid-β₄₂ fibrilization and oligomerization using the high-throughput screening formats of thioflavin T assay and multimer detection system, respectively. The potential neuroprotective effect of t3-(4-hydroxyphenyl)-2H-chromen-7-ol (SPA1413), also known as dehydroequol, idronoxil or phenoxodiol, was evaluated in cells and in 5xFAD (B6SJL) transgenic mouse, a model of Alzheimer's disease.

KEY RESULTS

SPA1413 had a potent inhibitory action on both amyloid-β fibrilization and oligomerization. In the cellular assay, SPA1413 prevented amyloid-β-induced cytotoxicity and reduced neuroinflammation. Remarkably, the oral administration of SPA1413 ameliorated cognitive impairment, decreased amyloid-β plaques and activated microglia in the brain of 5xFAD (B6SJL) transgenic mouse.

CONCLUSION AND IMPLICATIONS

Our results strongly support the repurposing of SPA1413, which has already received fast-track status from the US Food and Drug Administration (FDA) for cancer treatment, for the treatment of Alzheimer's disease due to its potent anti-amyloidogenic and anti-neuroinflammatory actions.