Protective effects of 6,7,4'-trihydroxyisoflavone, a major metabolite of daidzein, on 6-hydroxydopamine-induced neuronal cell death in SH-SY5Y human neuroblastoma cells

Daidzein's potential in halting neurodegeneration: unveiling mechanistic insights

Neurological conditions encompassing a wide range of disorders pose significant challenges globally. The complex interactions among signaling pathways and molecular elements play pivotal roles in the initiation and progression of neurodegenerative diseases. Isoflavones have emerged as a promising candidate to fight against neurodegenerative diseases. Daidzein, a 7-hydroxy-3-(4-hydroxyphenyl)-chromen-4-one, belongs to the isoflavone class and exhibits a diverse pharmacological profile. It is found primarily in soybeans and soy products, as well as in some other legumes and herbs. Investigations into daidzein have revealed that it confers neuroprotection by inhibiting oxidative stress, inflammation, and apoptosis, which are key contributors to neuronal damage and degeneration. Activating pathways like PI3K/Akt/mTOR and promoting neurotrophic factors like BDNF by daidzein underscore its potential in supporting neuronal function and combating neurodegeneration. Daidzein's effects on dopamine provide further avenues for intervention in conditions like Parkinson's disease. Additionally, the modulation of inflammatory and NRF-2-antioxidant signaling by daidzein reinforces its neuroprotective role. Moreover, daidzein's interaction with receptors and cellular processes like ER-β, GPR30, MAO, VEGF, and GnRH highlights its multifaceted effects across multiple pathways involved in neuroprotection and neuronal function. This review article delves into the mechanistic interplay of various mediators in mediating the neuroprotective effects of daidzein. The review article consolidates and analyzes research published over nearly two decades (2005-2024) from various databases, including PubMed, Scopus, ScienceDirect, and Web of Science, to provide a comprehensive understanding of daidzein's effects and mechanisms in neuroprotection.

Unveiling the neuroprotective properties of isoflavones: current evidence, molecular mechanisms and future perspectives

Neurodegenerative diseases encompass a wide range of debilitating and incurable brain disorders characterized by the progressive deterioration of the nervous system's structure and function. Isoflavones, which are naturally occurring polyphenolic phytochemicals, have been found to regulate various cellular signaling pathways associated with the nervous system. The main objective of this comprehensive review is to explore the neuroprotective effects of isoflavones, elucidate the underlying mechanisms, and assess their potential for treating neurodegenerative disorders. Relevant data regarding isoflavones and their impact on neurodegenerative diseases were gathered from multiple library databases and electronic sources, including PubMed, Google Scholar, Web of Science, and Science Direct. Numerous isoflavones, including genistein, daidzein, biochanin A, and formononetin, have exhibited potent neuroprotective properties against various neurodegenerative diseases. These compounds have been found to modulate neurotransmitters, which in turn contributes to their ability to protect against neurodegeneration. Both in vitro and in vivo experimental studies have provided evidence of their neuroprotection mechanisms, which involve interactions with estrogenic receptors, antioxidant effects, anti-inflammatory properties, anti-apoptotic activity, and modulation of neural plasticity. This review aims to provide current insights into the neuroprotective characteristics of isoflavones and shed light on their potential therapeutic applications in future clinical scenarios.

Molecular action of larvicidal flavonoids on ecdysteroidogenic glutathione S-transferase Noppera-bo in Aedes aegypti

Background

Mosquito control is a crucial global issue for protecting the human community from mosquito-borne diseases. There is an urgent need for the development of selective and safe reagents for mosquito control. Flavonoids, a group of chemical substances with variable phenolic structures, such as daidzein, have been suggested as potential mosquito larvicides with less risk to the environment. However, the mode of mosquito larvicidal action of flavonoids has not been elucidated.

Results

Here, we report that several flavonoids, including daidzein, inhibit the activity of glutathione S-transferase Noppera-bo (Nobo), an enzyme used for the biosynthesis of the insect steroid hormone ecdysone, in the yellow fever mosquito Aedes aegypti. The crystal structure of the Nobo protein of Ae. aegypti (AeNobo) complexed with the flavonoids and its molecular dynamics simulation revealed that Glu113 forms a hydrogen bond with the flavonoid inhibitors. Consistent with this observation, substitution of Glu113 with Ala drastically reduced the inhibitory activity of the flavonoids against AeNobo. Among the identified flavonoid-type inhibitors, desmethylglycitein (4′,6,7-trihydroxyisoflavone) exhibited the highest inhibitory activity in vitro. Moreover, the inhibitory activities of the flavonoids correlated with the larvicidal activity, as desmethylglycitein suppressed Ae. aegypti larval development more efficiently than daidzein.

Conclusion

Our study demonstrates the mode of action of flavonoids on the Ae. aegypti Nobo protein at the atomic, enzymatic, and organismal levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01233-2.

Pinocembrin-7-Methylether Protects SH-SY5Y Cells Against 6-Hydroxydopamine-Induced Neurotoxicity via Modulating Nrf2 Induction Through AKT and ERK Pathways

The present study aimed to evaluate the neuroprotective effects and underlying mechanisms of pinocembrin-7-methylether (PME), a natural bioflavonoid, in 6-hydroxydopamine (6-OHDA)-induced models of Parkinson's disease in vivo and in vitro. First, we found that PME decreased apoptosis in 6-OHDA-intoxicated SH-SY5Y cells. PME also blocked several 6-OHDA-induced mitochondrial apoptotic cascades, including loss of mitochondrial membrane potential, caspase 3 and PARP activation, and a decrease in the Bcl-2/Bax ratio. Also, PME suppressed 6-OHDA-induced oxidative stress while increasing antioxidant enzymatic activity. Further investigations indicated that PME significantly enhanced nuclear accumulation of Nrf2, improved ARE promoter activity, and upregulated HO-1 and NQO1 expression levels. In addition, siRNA-mediated Nrf2 knockdown abolished PME-induced anti-oxidative and anti-apoptotic effects. Interestingly, we found that PME promoted phosphorylation of AKT and ERK, whereas pharmacological inhibition of AKT or ERK pathways diminished PME-induced Nrf2 activation and protective actions. Moreover, PME attenuated 6-OHDA-induced loss of dopaminergic neurons and ameliorated locomotor deficiency in zebrafish, supporting the neuroprotective actions of PME in vivo. In summary, we found that PME conferred neuroprotection against 6-OHDA-induced neurotoxicity in PD models in vivo and in vitro. Taken together, our findings suggest that activation of Nrf2/ARE/HO-1 signaling cascades contributes to PME-induced anti-oxidative and neuroprotective actions, which are at least partially mediated by AKT and ERK pathways.

Antineuroinflammatory Effects of 7,3',4'-Trihydroxyisoflavone in Lipopolysaccharide-Stimulated BV2 Microglial Cells through MAPK and NF-κB Signaling Suppression

Neuroinflammation—a common pathological feature of neurodegenerative disorders such as Alzheimer’s disease—is mediated by microglial activation. Thus, inhibiting microglial activation is vital for treating various neurological disorders. 7,3’,4’-Trihydroxyisoflavone (THIF)—a secondary metabolite of the soybean compound daidzein—possesses antioxidant and anticancer properties. However, the effects of 7,3’,4’-THIF on microglial activation have not been explored. In this study, antineuroinflammatory effects of 7,3’,4’-THIF in lipopolysaccharide (LPS)-stimulated BV2 microglial cells were examined. 7,3’,4’-THIF significantly suppressed the production of the proinflammatory mediators nitric oxide (NO), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) as well as of the proinflammatory cytokine interleukin-6 (IL-6) in LPS-stimulated BV2 microglial cells. Moreover, 7,3’,4’-THIF markedly inhibited reactive oxygen species (ROS) generation. Western blotting revealed that 7,3’,4’-THIF diminished LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), glycogen synthase kinase-3β (GSK-3β), and nuclear factor kappa B (NF-κB). Overall, 7,3’,4’-THIF exerts antineuroinflammatory effects against LPS-induced microglial activation by suppressing mitogen-activated protein kinase (MAPK) and NF-κB signaling, ultimately reducing proinflammatory responses. Therefore, these antineuroinflammatory effects of 7,3’,4’-THIF suggest its potential as a therapeutic agent for neurodegenerative disorders.

Redox imbalance induced by docetaxel in the neuroblastoma SH-SY5Y cells: a study of docetaxel-induced neuronal damage

Objectives

In cancer survivors, chemotherapy-associated adverse neurological effects are described as side effects in non-targeted tissue. We investigated the role of redox-imbalance in neuronal damage by a relative low dose of Docetaxel (DTX).

Methods

The neuroblastoma cells (SH-SY5Y cells) were exposed to DTX at a dose of 1.25 nM for 6 h. Antioxidant defenses (i.e. ascorbic acid, glutathione, and catalase) and lipid oxidation products (i.e. F₂-isoprostanes) were evaluated. To investigate cell ultrastructure and tubulin localisation, transmission electron microscopy (TEM) and immunofluorescence techniques were applied.

Results

In the SH-SY5Y cells, DTX induced a significant reduction of total glutathione (P < 0.001) and ascorbic acid (P < 0.05), and an increase in both total F₂-Isoprostanes (P < 0.05) and catalase activity (P < 0.05), as compared to untreated cells. Additionally, TEM showed a significant increase in cells with apoptotic characteristics. Immunolocalisation of tubulin showed a compromised cytoskeletal organisation.

Discussion

The investigated sublethal dose of DTX, to which non-targeted cells may be exposed throughout the duration of chemotherapy treatment, induces a redox imbalance resulting in a specific modulation of the antioxidant response. This study provides new insights into DTX-induced cellular mechanisms useful for evaluating whether the concomitant use of antioxidants associated with chemotherapy mitigates chemotherapy side effects in cancer survivors.