Dihydroactinidiolide regulates Nrf2/HO-1 expression and inhibits caspase-3/Bax pathway to protect SH-SY5Y human neuroblastoma cells from oxidative stress induced neuronal apoptosis

Unveiling Potential Neurotoxic Mechansisms: Pb-Induced Activation of CDK5-p25 Signaling Axis in Alzheimer's Disease Development, Emphasizing CDK5 Inhibition and Formation of Toxic p25 Species

Alzheimer's disease (AD) is a complex neurodegenerative disorder with an etiology influenced by various genetic and environmental factors. Heavy metals, such as lead (Pb), have been implicated in AD pathogenesis, but the underlying mechanisms remain poorly understood. This study investigates the potential neurodegenerative role of Pb and amyloid β peptides (1-40 and 25-35) via their interaction with cyclin-dependent kinase 5 (CDK5) and its activator, p25, in an attempt to unravel the molecular basis of Pb-induced neurotoxicity in neuronal cells. To this end, a CDK5 inhibitor was utilized to selectively inhibit CDK5 activity and investigate its impact on neurodegeneration. The results revealed that Pb exposure led to elevated Pb uptake (56.7% at 15 μM Pb) and disturbances in intracellular calcium (19.6% increase upon Pb treatment). The results revealed a significant decrease in total antioxidant capacity (by 88.6% upon Pb treatment) and also elevation in protein carbonylation (by 26.2% upon Pb and Aβp's combination treatment), indicative of oxidative damage, suggesting an impaired cellular defence against oxidative stress and elevated DNA oxidative damage (178 pg/ml and 182 pg/ml of 8-OH-dG upon Pb and All treatment). Additionally, dysregulations in levels of calpain, p25-35 and CDK5 are observed and markers associated with antioxidant metabolism (phospho-Peroxiredoxin 1), DNA damage responses (phospho-ATM and phospho-p53), and nuclear membrane disruption (phospho-lamin A/C) were observed, supporting the role of Pb-induced CDK5-p25 signaling in AD pathogenesis. These findings shed light on the intricate molecular events underlying Pb-induced neurotoxicity and provide valuable insights into the mechanisms that contribute to AD development.

Protective Effects of Heat-Killed Ruminococcus albus against β-Amyloid-Induced Apoptosis on SH-SY5Y Cells

A high level of β-amyloid (Aβ) in the brains of patients with Alzheimer's disease (AD) generates reactive oxygen species that induce neuronal death and DNA damage. The interaction between the gut microbiota and brain health has attracted attention in recent years. Heat-killed Ruminococcus albus (hkRA) reportedly protects neurons against damage induced by oxidative stress. However, whether hkRA can inhibit Aβ-induced apoptosis and thus alleviate AD remains unclear. Hence, we aimed to evaluate the protective effects of hkRA against Aβ-induced apoptosis on the human neuroblastoma SH-SY5Y cell. HkRA treatment (108 cells/ml) significantly decreased the Aβ-induced cytotoxicity and DNA damage in the SH-SY5Y cells. It also showed a significant increase of the bax/bcl-2 ratio in the Aβ-treated SH-SY5Y cells. Moreover, hkRA treatment stimulated the expression of antioxidation-related genes HO-1, Nrf2, and PKC-δ and increased the expression of brain-derived neurotrophic factor (BDNF). Meanwhile, it significantly decreased the activity of caspase-3 and protein expression of cleaved caspase-3 in the Aβ-treated SH-SY5Y cells. Additionally, the protein levels of mitochondrial and cytosolic cytochrome c increased and decreased, respectively, in the cells. These results suggest that hkRA protects human neuroblastoma cells from Aβ-induced apoptosis and oxidative stress. Thus, hkRA may be developed into a health-promoting paraprobiotic (the inactivated microbial cells of probiotics) for patients with AD.

Hesperidin Methyl Chalcone reduces extracellular Aβ(25-35) peptide aggregation and fibrillation and also protects Neuro 2a cells from Aβ(25-35) induced neuronal dysfunction

In the present study, we evaluated the neuroprotective potential of Hesperidin Methyl Chalcone (HMC) against the neurotoxicity induced by Aβ(25-35) peptide. HMC demonstrated higher free-radical scavenging activity than Hesperidin in initial cell-free studies. Investigations using the fluorescent dye thioflavin T with Aβ(25-35) peptide showed that HMC has the ability to combat extracellular amyloid aggregation by possessing anti-aggregation property against oligomers and by disaggregating mature fibrils. Also, the results of the molecular simulation studies show that HMC ameliorated oligomer formation. Further, the anti-Alzheimer's property of HMC was investigated in in vitro cell conditions by pre-treating the neuro 2a (N2a) cells with HMC before inducing Aβ(25-35) toxicity. The findings demonstrate that HMC increased cell viability, reduced oxidative stress, prevented macromolecular damage, allayed mitochondrial dysfunction, and exhibited anticholinesterase activity. HMC also reduced Aβ induced neuronal cell death by modulating caspase-3 activity, Bax expression and Bcl2 overexpression, demonstrating that HMC pre-treatment reduced mitochondrial damage and intrinsic apoptosis induced by Aβ(25-35).In silico evaluation against potential AD targets reveal that HMC could be a potent inhibitor of BACE-1, inhibiting the formation of toxic Aβ peptides. Overall, the findings imply that the neuroprotective efficacy of HMC has high prospects for addressing a variety of pathogenic consequences caused by amyloid beta in AD situations and alleviating cognitive impairments.

Effects of Perilla Seed Meal on Productive Performance, Egg Quality, Antioxidant Capacity and Hepatic Lipid Metabolism of Wenchang Breeder Hens

The aim of this study was to investigate the effects of adding perilla seed meal (PSM) to the diet on reproductive performance, egg quality, yolk fatty acids, antioxidant capacity and liver lipid metabolism in breeding hens. A total of 192 31-week-old yellow-feathered hens were randomly divided into 4 treatments with 6 replicates of 8 birds for 8 weeks. The chickens were fed a typical corn-soybean meal diet containing 0% (control), 0.3%, 0.6%, and 1% PSM. The results showed that PSM can change the productivity of laying hens. Adding 0.6% PSM to the feed reduced the mortality rate of chickens. Adding 1% PSM improved the fertilization rate and hatching rate of chickens. Regarding egg quality, the albumen height and Haugh unit were improved in the 0.6% PSM group. The content of MUFAs and PUFAs in the egg yolk was increased in all the PSM groups, while SFAs were only increased in the 0.6% PSM group. Among the indicators related to lipid metabolism, serum GLU decreased in all the PSM groups. The 0.6% PSM group had a reduction in serum and liver TG, as well as reductions in serum LDL-C and ALT. The same results were observed for the abdominal fat percentage in the 0.6% PSM group. Liver lipid metabolism-associated gene expression of FAS and LXRα was decreased in all the PSM groups, and the mRNA expression of ACC and SREBP-1c was significantly reduced in the 0.6% PSM group. HE staining showed that the vacuoles in the liver tissue gradually decreased with increasing PSM doses, especially the 1% PSM dose. Lipid droplets with a similar trend were observed using Oil Red O staining. In the results of the antioxidant capacity test, the serum T-AOC was increased in the 0.6% and 1% PSM groups, and the SOD in both the serum and liver was significantly increased in all the PSM groups. The expression of antioxidant-related genes such as Nrf2, NQO-1, HO-1, CAT and GSH-Px was significantly upregulated in the 1% PSM group. In conclusion, the PSM diet improved the lipid metabolism and antioxidant capacity of breeding hens. PSM reduces mortality and improves fertilization and hatchability in the late laying period of chickens, resulting in greater benefits. We recommend adding 0.6% PSM to layer feed, which improves the physical condition of the hens and brings higher economic benefits.

A Bidens pilosa L. Non-Polar Extract Modulates the Polarization of Human Macrophages and Dendritic Cells into an Anti-Inflammatory Phenotype

Different communities around the world traditionally use Bidens pilosa L. for medicinal purposes, mainly for its anti-inflammatory, antinociceptive, and antioxidant properties; it is used as an ingredient in teas or herbal medicines for the treatment of pain, inflammation, and immunological disorders. Several studies have been conducted that prove the immunomodulatory properties of this plant; however, it is not known whether the immunomodulatory properties of B. pilosa are mediated by its ability to modulate antigen-presenting cells (APCs) such as macrophages (MØs) and dendritic cells (DCs) (through polarization or the maturation state, respectively). Different polar and non-polar extracts and fractions were prepared from the aerial part of B. pilosa. Their cytotoxic and immunomodulatory effects were first tested on human peripheral blood mononuclear cells (PBMCs) and phytohemagglutinin (PHA)-stimulated PBMCs, respectively, via an MTT assay. Then, the non-cytotoxic plant extracts and fractions that showed the highest immunomodulatory activity were selected to evaluate their effects on human MØ polarization and DC maturation (cell surface phenotype and cytokine secretion) through multiparametric flow cytometry. Finally, the chemical compounds of the B. pilosa extract that showed the most significant immunomodulatory effects on human APCs were identified using gas chromatography coupled with mass spectrometry. The petroleum ether extract and the ethyl acetate and hydroalcoholic fractions obtained from B. pilosa showed low cytotoxicity and modulated the PHA-stimulated proliferation of PBMCs. Furthermore, the B. pilosa petroleum ether extract induced M2 polarization or a hybrid M1/M2 phenotype in MØs and a semi-mature status in DCs, regardless of exposure to a maturation stimulus. The immunomodulatory activity of the non-polar (petroleum ether) extract of B. pilosa on human PBMC proliferation, M2 polarization of MØs, and semi-mature status in DCs might be attributed to the low-medium polarity components in the extract, such as phytosterol terpenes and fatty acid esters.

Mitochondrial Hydrogen Peroxide Activates PTEN and Inactivates Akt Leading to Autophagy Inhibition-Dependent Cell Death in Neuronal Models of Parkinson's Disease

Defective autophagy relates to the pathogenesis of Parkinson's disease (PD), a typical neurodegenerative disease. Our recent study has demonstrated that PD toxins (6-OHDA, MPP+, or rotenone) induce neuronal apoptosis by impeding the AMPK/Akt-mTOR signaling. Here, we show that treatment with 6-OHDA, MPP+, or rotenone triggered decreases of ATG5/LC3-II and autophagosome formation with a concomitant increase of p62 in PC12, SH-SY5Y cells, and primary neurons, suggesting inhibition of autophagy. Interestingly, overexpression of wild-type ATG5 attenuated the inhibitory effect of PD toxins on autophagy, reducing neuronal apoptosis. The effects of PD toxins on autophagy and apoptosis were found to be associated with activation of PTEN and inactivation of Akt. Overexpression of dominant negative PTEN, constitutively active Akt and/or pretreatment with rapamycin rescued the cells from PD toxins-induced downregulation of ATG5/LC3-II and upregulation of p62, as well as consequential autophagosome diminishment and apoptosis in the cells. The effects of PD toxins on autophagy and apoptosis linked to excessive intracellular and mitochondrial hydrogen peroxide (H2O2) production, as evidenced by using a H2O2-scavenging enzyme catalase, a mitochondrial superoxide indicator MitoSOX and a mitochondria-selective superoxide scavenger Mito-TEMPO. Furthermore, we observed that treatment with PD toxins reduced the protein level of Parkin in the cells. Knockdown of Parkin alleviated the effects of PD toxins on H2O2 production, PTEN/Akt activity, autophagy, and apoptosis in the cells, whereas overexpression of wild-type Parkin exacerbated these effects of PD toxins, implying the involvement of Parkin in the PD toxins-induced oxidative stress. Taken together, the results indicate that PD toxins can elicit mitochondrial H2O2, which can activate PTEN and inactivate Akt leading to autophagy inhibition-dependent neuronal apoptosis, and Parkin plays a critical role in this process. Our findings suggest that co-manipulation of the PTEN/Akt/autophagy signaling by antioxidants may be exploited for the prevention of neuronal loss in PD.

Hesperidin methylchalcone (HMC) hinders amyloid-β induced Alzheimer's disease by attenuating cholinesterase activity, macromolecular damages, oxidative stress and apoptosis via regulating NF-κB and Nrf2/HO-1 pathways

Phytocompounds therapy has recently emerged as an effective strategy to treat Alzheimer's disease. Herein, the protective effect of hesperidin methylchalcone (HMC) was evaluated through Alzheimer's disease models of Neuro-2a cells and Wistar rats. The in vitro results showed that HMC possesses significant ability to inhibit the acetylcholinesterase enzyme and exhibiting anti-aggregation and disaggregation properties. Furthermore, HMC could protect the Neuro-2a cells against Aβ-induced neurotoxicity. Simultaneously, HMC treatment significantly improved the cognitive deficits caused by Aβ-peptide on spatial memory in Wistar rats. HMC significantly enhanced the cholinergic effects by inhibiting AChE, BuChE, β-secretase activity, caspase-3 activity, and attenuating macromolecular damages and apoptosis. Notably, HMC reduced the Aβ-induced oxidative stress by activating the antioxidative defence enzymes. In addition, the HMC treatment suppressed the expression of immunocytokines such as p-NF-κB p65, p-IκBα, induced by Aβ; whereas upregulating Nrf2, HO-1 in brain homogenate. These results suggest that HMC could attenuate Aβ-induced neuroinflammation in brain via suppressing NF-κB signalling pathway and activating the Nrf2/HO-1 pathway, thereby improving memory and cognitive impairments in Wistar rats. Overall, the present study reports that HMC can act as a potent candidate with multi-faceted neuroprotective potential against Aβ-induced memory dysfunction in Wistar rats for the treatment of Alzheimer's disease.

Natural Products as Modulators of Nrf2 Signaling Pathway in Neuroprotection

Neurodegenerative diseases (NDs) affect the West due to the increase in life expectancy. Nervous cells accumulate oxidative damage, which is one of the factors that triggers and accelerates neurodegeneration. However, cells have mechanisms that scavenge reactive oxygen species (ROS) and alleviate oxidative stress (OS). Many of these endogenous antioxidant systems are regulated at the gene expression level by the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). In the presence of prooxidant conditions, Nrf2 translocates to the nucleus and induces the transcription of genes containing ARE (antioxidant response element). In recent years, there has been an increase in the study of the Nrf2 pathway and the natural products that positively regulate it to reduce oxidative damage to the nervous system, both in in vitro models with neurons and microglia subjected to stress factors and in vivo models using mainly murine models. Quercetin, curcumin, anthocyanins, tea polyphenols, and other less studied phenolic compounds such as kaempferol, hesperetin, and icariin can also modulate Nrf2 by regulating several Nrf2 upstream activators. Another group of phytochemical compounds that upregulate this pathway are terpenoids, including monoterpenes (aucubin, catapol), diterpenes (ginkgolides), triterpenes (ginsenosides), and carotenoids (astaxanthin, lycopene). This review aims to update the knowledge on the influence of secondary metabolites of health interest on the activation of the Nrf2 pathway and their potential as treatments for NDs.

Ginseng oligosaccharides protect neurons from glutamate-induced oxidative damage through the Nrf2/HO-1 signaling pathway

The effects of ginseng oligosaccharides (GSOs) on neuronal oxidative injury induced by glutamate (GLU) and the molecular mechanisms involved were investigated. Cell damage was assessed using MTT assays, and the lactate dehydrogenase (LDH) release rate and flow cytometry were used to detect the accumulation of reactive oxygen species (ROS) and mitochondrial membrane potential respectively. The levels of catalase (CAT) and glutathione (GSH) were measured in PC12 cells and Drosophila brain tissue. The climbing ability of Drosophila was observed. Levels of proteins, including Cyt C, Bcl-2/BAX, and Nrf2/HO-1-associated proteins, were determined by western blotting and immunofluorescence. It was found that GSOs reversed GLU-induced reductions in cell viability and the LDH release rate, and rescued ROS accumulation. GSOs also mitigated the deleterious effects of GLU on the mitochondrial membrane potential and Cyt C release, thus alleviating mitochondrial dysfunction, and increased GSH levels and CAT activity in both cells and Drosophila brain tissue. The climbing index in GSO-treated Drosophila was significantly higher than that in the tert-butyl-hydroperoxide-treated flies. Furthermore, GSOs protected cells against GLU-induced apoptosis by reducing the expression of the mitochondrial apoptosis-associated Bcl-2 family effector proteins and protected cells from GLU-induced oxidative damage by increasing the nuclear translocation of Nrf2 and HO-1 expression. These findings indicate that GSOs protect against GLU-induced neuronal oxidative damage through Nrf2/HO-1 activation.

Mitigation of oxidative stress with dihydroactinidiolide, a natural product against scopolamine-induced amnesia in Swiss albino mice

The present work describes the neuroprotective efficacy of DHAc under escalated oxidative stress condition in scopolamine-induced amnesic mice. During the toxicity test of DHAc in mice, the acute dose (LD₅₀) is found to be 3.468 mg/kg bw and the sub-acute dose is 0.68 mg/kg bw. Improved cognitive and learning abilities are observed in Morris water maze and Y-maze test in 10 days DHAc (0.68 mg/kg bw) treated scopolamine-induced male Swiss albino mice. In the molecular level these changes are monitored as reduced oxidative load followed by significantly lower lipid peroxidation and protein carbonylation, increased superoxide dismutase, catalase, acetylcholinesterase, caspase-3 activity and glutathione content followed by higher expression of anti apoptotic protein bcl-2 in mice brain as compared to scopolamine (1 mg/kg bw) treated mice. Meanwhile real time PCR shows higher expression of brain derived neurotrophic factor (BDNF) and synaptophysin in DHAc pretreated scopolamine treated mice brain. HPLC analysis suggested its possible blood brain barrier crossing ability. Overall DHAc reversed behavioral anomalies in the scopolamine treated mice via oxidative stress quenching, enhancing antioxidative enzyme activity, enhancing BDNF and synaptophysin mRNA levels and reducing expression of apoptotic protein Bax.

Biochanin A protects SH-SY5Y cells against isoflurane-induced neurotoxicity by suppressing oxidative stress and apoptosis

Biochanin A (BCA) is a natural organic O-methylated isoflavone with a variety of pharmacological effects, and has been reported to have neuroprotective properties. Here, we explored whether BCA protects neurocytes against isoflurane-induced neurotoxicity and investigated the underlying mechanism. Cell viability was tested by cell counting kit-8 and lactate dehydrogenase release assays. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3/7 activity assays. Superoxide dismutase (SOD) and catalase (CAT) activities and levels of glutathione (GSH) and malondialdehyde (MDA) were measured to assess oxidative stress. Expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase (NQO1) was determined by western blotting. Treatment with BCA significantly attenuated the reduction of cell viability induced by isoflurane in SH-SY5Y cells. In addition, BCA treatment reversed isoflurane-induced SOD and CAT activity reduction, GSH level decline and MDA level increase. Isoflurane-induced apoptosis was also attenuated by treatment with BCA. The increase in nuclear Nrf2, HO-1 and NQO1 expression induced by isoflurane was amplified by treatment with BCA. These inhibitory effects of BCA on isoflurane-induced oxidative stress, viability reduction and cell apoptosis were attenuated in Nrf2 knockdown SH-SY5Y cells. Our findings indicate that BCA protects SH-SY5Y cells against isoflurane-induced neurotoxicity via inducing the Nrf2/ARE pathway.