Neuroprotective effects of Quercetin on radiation-induced brain injury in rats

Neuroprotective effect of resveratrol against radiation after surgically induced brain injury by reducing oxidative stress, inflammation, and apoptosis through NRf2/HO-1/NF-κB signaling pathway

The impact of resveratrol (RSV) on radiation (RAD)-induced brain injury in rats' brains was investigated. A total of 40 male Wistar Albino rats were randomly divided into four groups (control, RAD, RAD + RSV, and RSV groups, with 10 rats in each group). The results revealed a significant decrease in catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase activities, as well as glutathione (GSH) content. Further, a significant elevation in malondialdehyde, nitric oxide, interleukin-1-beta (IL-1β), IL-6, and transforming growth factor-β1 levels were observed. Furthermore, decreased B-cell lymphoma 2 (Bcl-2), increased Bcl-2-associated X, and tumor necrosis factor-α genes expression, decreased nuclear factor erythroid-related factor 2, heme oxygenase-1, and increased nuclear factor-κB protein levels were noticed. Also, an apoptosis marker, caspase-3-positive cells, was seen in the hippocampus. Those effects were observed in the RAD group of rats. The treatment of RSV displayed a significant amendment of the studied parameters in the brain tissues of the RAD group of animals. This effect is interrelated to the ability of RSV to scavenge the free radicals, enhance the activity of the antioxidant enzymes, increase GSH contents, and downregulate the inflammatory responses and apoptosis markers in the brain tissues of RAD animals. In conclusion, this study demonstrated that the potent antioxidant, anti-inflammatory, and antiapoptotic activities of RSV can improve the antioxidant status and suppress the inflammatory responses and apoptosis in the brain tissues of RAD animals.

Neuroprotective Role of Quercetin on Rotenone-Induced Toxicity in SH-SY5Y Cell Line Through Modulation of Apoptotic and Autophagic Pathways

The detrimental impact on the food chain due to the overuse of rotenone is partly responsible for alpha-synuclein (α-syn) mediated neurotoxicity. It is hypothesized that rotenone overdose leads to cytosolic proteopathy resulting in modulation of apoptosis and autophagic pathways. The aim of our study is to explore the neuroprotective role of quercetin, a beneficial polyphenol against rotenone-induced neurotoxicity in dopaminergic human SH-SY5Y cell lines. In our study we demonstrated the correlation of rotenone-induced neurotoxicity through elevation of intracellular reactive oxygen species (ROS) and imbalance in the mitochondrial membrane potential (MMP). Moreover, the morphological distortion of cell, condensation of nuclei, externalization of the inner phosphatidylserine, cleavage of caspase 3, and Poly ADP Ribose Polymerase (PARP) confirmed apoptosis. However, all these lethal effects were ameliorated by treatment of quercetin to the cells. On the other hand rotenone has a strong effect on autophagy which is a regulated degrading and recycling cellular process to remove dysfunctional proteins. Indeed, rotenone-mediated autophagy resulted in the enhancement of autophagosome-bound microtubule-associated protein light chain-3 (LC3-II) expression. Furthermore, excess accumulation of acidic vesicles was detected in presence of rotenone. Lysosome associated membrane protein (LAMP-2A) is yet another crucial protein that recruits overexpressed or misfolded proteins into the lumen of lysosome to trigger autophagy. In all cases the impact of rotenone on the cells acquired significant protection through quercetin treatment. In the present work we therefore opine the prospects of quercetin as a therapeutic candidate against neurotoxicity.

Neuroprotective effect of quercetin nanoparticles: A possible prophylactic and therapeutic role in alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is the most common cause of dementia in elderly. Quercetin is a well-known flavonoid with low bioavailability. Recently, quercetin nanoparticles (QNPs) has been shown to have a better bioavailability.

AIMS

This study aimed to investigate the protective and therapeutic effects of QNPs in Aluminum chloride (AlCl₃) induced animal model of AD.

MATERIALS AND METHODS

AD was induced in rats by oral administration of AlCl₃ (100 mg/kg/day) for 42 days. QNPs (30 mg/kg) was given along with AlCl₃ in the prophylactic group and following AD induction in the treated group. Hippocampi were harvested for assessments of the structural and ultrastructural changes using histological and histochemical approaches.

RESULTS AND DISCUSSION

AD hippocampi showed a prominent structural and ultrastructural disorders both neuronal and extraneuronal. Including neuronal degeneration, formation of APs and NFTs, downregulation of tyrosine hydroxylase (TH), astrogliosis and inhibition of the proliferative activity (all P ≤ 0.05). Electron microscopy showed signs of neuronal degeneration with microglia and astrocyte activation and disruption of myelination and Blood Brain Barrier (BBB). Interestingly, QNPs administration remarkably reduced the neuronal degenerative changes, APs and NFTs formation (all P ≤ 0.05). Furthermore, it showed signs of regeneration (all P ≤ 0.05) and upregulation of TH. The effect was profound in the prophylactic group. Thus, QNPs reduced the damaging effect of AlCl₃ on hippocampal neurons at the molecular, cellular and subcellular levels.

CONCLUSION

For the best of our knowledge this is the first study to show a prophylactic and therapeutic effect for QNPs in AD model. This might open the gate for further research and provide a new line for therapeutic intervention in AD.

Forced running exercise mitigates radiation-induced cognitive deficits via regulated DNA hydroxymethylation

Aim: Roles of forced running exercise (FE) in remediation of neurogenesis inhibition and radiation-induced cognitive dysfunction were investigated in a whole-brain irradiation mice model via the regulation of DNA 5-hydroxymethylation modification (5 hmC) and its catalytic enzymes ten-eleven translocation (Tet) proteins. Materials & methods: Hippocampal neurogenesis and cognitive function, DNA 5 hmC level and Tet expression were determined in mice. Results: The expression of DNA 5 hmC and Tet2, brain-derived neurotrophic factor significantly decreased in hippocampus postradiation. FE mitigated radiation-induced neurogenesis deficits and cognitive dysfunction. Furthermore, FE increased 5 hmC and brain-derived neurotrophic factor expression. SC1, a Tet inhibitor, reversed partly such changes. Conclusion: Tet-mediated 5 hmC modification represents a kind of diagnostic biomarkers of radiation-induced cognitive dysfunction. Targeting Tet-related epigenetic modification may be a novel therapeutic strategy for radiation-induced brain injury.

Radiation-induced brain injury: current concepts and therapeutic strategies targeting neuroinflammation

Continued improvements in cancer therapies have increased the number of long-term cancer survivors. Radiation therapy remains one of the primary treatment modalities with about 60% of newly diagnosed cancer patients receiving radiation during the course of their disease. While radiation therapy has dramatically improved patient survival in a number of cancer types, the late effects remain a significant factor affecting the quality of life particularly in pediatric patients. Radiation-induced brain injury can result in cognitive dysfunction, including hippocampal-related learning and memory dysfunction that can escalate to dementia. In this article, we review the current understanding of the mechanisms behind radiation-induced brain injury focusing on the role of neuroinflammation and reduced hippocampal neurogenesis. Approaches to prevent or ameliorate treatment-induced side effects are also discussed along with remaining challenges in the field.

Enhancing the potential preclinical and clinical benefits of quercetin through novel drug delivery systems

Quercetin is reported to have numerous pharmacological actions, including antidiabetic, anti-inflammatory and anticancer activities. The main mechanism responsible for its pharmacological activities is its ability to quench reactive oxygen species (ROS) and, hence, decrease the oxidative stress responsible for the development of various diseases. Despite its proven therapeutic potential, the clinical use of quercetin remains limited because of its low aqueous solubility, bioavailability, and substantial first-pass metabolism. To overcome this, several novel formulations have been reported. In this review, we focus on the applications of quercetin extract as well as its novel formulations for treating different disorders. We also examine its proposed mechanism of action of quercetin.

Synthesis, characterization and efficacy of mitochondrial targeted delivery of TPP-curcumin in rotenone-induced toxicity

BACKGROUND

Mitochondrial impairments due to free radicals are implicated in a wide range of neurotoxicological alterations. Curcumin, an active ingredient of turmeric has shown protective efficacy against oxidative damage due to its strong antioxidant potential, but its efficiency is restricted due to low bioavailability in the mitochondria. In view of this, we have synthesized mitochondria-targeted curcumin (MTC) with an aim to investigate its efficacy against rotenone-induced oxidative damage in mice and isolated mitochondria.

METHODS

MTC was synthesized by attaching the triphenylphosphonium cation (TPP) as a cationic carrier to the curcumin to assess its protective efficacy in rotenone-induced in-vitro and in-vivo toxicity in mice.

RESULTS

In-vitro treatment of rotenone in isolated mitochondria caused a significant increase in lipid peroxidation (2.74 fold, 3.62 fold), protein carbonyl contents (2.62 fold, 1.81 fold), and decrease in levels of reduced glutathione (2.02 fold, 1.70 fold) as compared to control. Pre-treatment of curcumin and MTC along with rotenone in the isolated mitochondria significantly reduce the oxidative stress as compared to those treated with rotenone alone. Rotenone treatment in mice significantly increased lipid peroxidation (2.02 fold) and decreased the levels of reduced glutathione (2.99 fold), superoxide dismutase (2.09 fold) and catalase (3.60 fold) in the liver as compared to controls. Co-treatment of curcumin and MTC along with rotenone significantly reduced lipid peroxidation (1.26 fold, 1.76 fold) and increased the levels of reduced glutathione (1.60 fold, 2.43 fold), superoxide dismutase (1.45 fold, 1.99 fold) and catalase (2.32 fold, 2.90 fold) as compared to those treated with rotenone alone.

CONCLUSION

The results of the present study indicate that the protective efficacy of MTC against rotenone-induced oxidative damage was more promising than curcumin in both in-vitro and in-vivo system which indicates the enhanced bioavailability of MTC. Graphical abstract Effect of mitochondrial targeted delivery of TPP-curcumin in rotenone-induced toxicity.

Antioxidant Activities of Quercetin and Its Complexes for Medicinal Application

Quercetin is a bioactive compound that is widely used in botanical medicine and traditional Chinese medicine due to its potent antioxidant activity. In recent years, antioxidant activities of quercetin have been studied extensively, including its effects on glutathione (GSH), enzymatic activity, signal transduction pathways, and reactive oxygen species (ROS) caused by environmental and toxicological factors. Chemical studies on quercetin have mainly focused on the antioxidant activity of its metal ion complexes and complex ions. In this review, we highlight the recent advances in the antioxidant activities, chemical research, and medicinal application of quercetin.

Neuroprotective effect of juçara (Euterpe edulis Martius) fruits extracts against glutamate-induced oxytosis in HT22 hippocampal cells

This study investigated the neuroprotective effect of juçara fruit extracts against glutamate-induced oxytosis in HT22 cells. Potential relationships between the extracts' polyphenolic composition and their protective/antioxidant capacities were also investigated. Experiments with the addition of either the crude methanolic extract or hexane, dichloromethane, ethyl acetate and butanol fractions 24 h before glutamate (pretreatment) and together with glutamate (co-treatment) were performed. At the concentration of 10 μg ml^-1, the hexane and dichloromethane fractions were able to protect cells, both in pretreatment and co-treatment. These fractions presented the highest number of quantified polyphenolics (24 and 21, respectively) although the total levels were 63-fold higher in the dichloromethane fraction. Syringaldehyde, vanillin and 4-aminobenzoic, cinnamic, salicylic and syringic acids were found only in these fractions. The dichloromethane fraction presented higher 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, while the butanol and ethyl acetate fractions showed higher ferric reducing antioxidant power. These results suggest juçara fruits extracts as promising for the reduction of the risk of neurodegenerative diseases.

Comparative Pharmacognosy, Chemical Profile and Antioxidant Activity of Extracts from Phania matricarioides (Spreng.) Griseb. Collected from Different Localities in Cuba

Phania matricarioides (Spreng.) Griseb. is a traditionally used plant with various pharmacological properties. However, there are only scarce reports about the phytochemistry and biological activity of this plant. In this work, P. matricarioides was collected from three different localities of Cuba: PmB (collected in Bauta, Artemisa), PmC (collected in Cangrejeras, Artemisa), and PmI (collected in La Lisa, Havana), extracted with aqueous ethanol, and analyzed macroscopically and microscopically. The extracts were screened for phytochemical contents, analyzed by TLC and HPLC, and screened for antioxidant activity using the FRAP and DPPH assays. Macroscopic analysis showed similar results for all samples; however, microscopic, physicochemical and phytochemical studies showed appreciable differences. In particular, the total solid of PmC extract was higher (1.94 ± 0.03%) than the other samples. In HPLC profiles, quercetin was identified in the three samples and a greater similarity between samples PmB and PmI was observed. All samples demonstrated radical-scavenging antioxidant activity by the DPPH assay, which PmC also demonstrated the smaller (p < 0.05) value (IC₅₀ = 27.4 ± 0.1 µg/mL), but was statistically superior (p < 0.05) to vitamin C (IC₅₀ = 23.7 ± 0 µg/mL). Also, in the FRAP assay, a higher vitamin C equivalent of PmC was significantly superior (p < 0.05) to the other extracts at the evaluated concentrations, which is likely due to a higher concentration of quercetin. In conclusion, P. matricarioides could constitute a potential resource in the field of phytotherapeutic products, and the results obtained can contribute to the development of the quality control norms for this species.